Initial import

28 files changed, 12377 insertions, 0 deletions

diff --git a/kernel/locking/Makefile b/kernel/locking/Makefile
new file mode 100644
index 000000000..de7a416cc
--- /dev/null
+++ b/kernel/locking/Makefile
@@ -0,0 +1,29 @@
+
+obj-y += mutex.o semaphore.o rwsem.o
+
+ifdef CONFIG_FUNCTION_TRACER
+CFLAGS_REMOVE_lockdep.o = $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_lockdep_proc.o = $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_mutex-debug.o = $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_rtmutex-debug.o = $(CC_FLAGS_FTRACE)
+endif
+
+obj-$(CONFIG_DEBUG_MUTEXES) += mutex-debug.o
+obj-$(CONFIG_LOCKDEP) += lockdep.o
+ifeq ($(CONFIG_PROC_FS),y)
+obj-$(CONFIG_LOCKDEP) += lockdep_proc.o
+endif
+obj-$(CONFIG_SMP) += spinlock.o
+obj-$(CONFIG_LOCK_SPIN_ON_OWNER) += osq_lock.o
+obj-$(CONFIG_SMP) += lglock.o
+obj-$(CONFIG_PROVE_LOCKING) += spinlock.o
+obj-$(CONFIG_RT_MUTEXES) += rtmutex.o
+obj-$(CONFIG_DEBUG_RT_MUTEXES) += rtmutex-debug.o
+obj-$(CONFIG_RT_MUTEX_TESTER) += rtmutex-tester.o
+obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o
+obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock_debug.o
+obj-$(CONFIG_RWSEM_GENERIC_SPINLOCK) += rwsem-spinlock.o
+obj-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem-xadd.o
+obj-$(CONFIG_PERCPU_RWSEM) += percpu-rwsem.o
+obj-$(CONFIG_QUEUE_RWLOCK) += qrwlock.o
+obj-$(CONFIG_LOCK_TORTURE_TEST) += locktorture.o
diff --git a/kernel/locking/lglock.c b/kernel/locking/lglock.c
new file mode 100644
index 000000000..86ae2aebf
--- /dev/null
+++ b/kernel/locking/lglock.c
@@ -0,0 +1,89 @@
+/* See include/linux/lglock.h for description */
+#include <linux/module.h>
+#include <linux/lglock.h>
+#include <linux/cpu.h>
+#include <linux/string.h>
+
+/*
+ * Note there is no uninit, so lglocks cannot be defined in
+ * modules (but it's fine to use them from there)
+ * Could be added though, just undo lg_lock_init
+ */
+
+void lg_lock_init(struct lglock *lg, char *name)
+{
+	LOCKDEP_INIT_MAP(&lg->lock_dep_map, name, &lg->lock_key, 0);
+}
+EXPORT_SYMBOL(lg_lock_init);
+
+void lg_local_lock(struct lglock *lg)
+{
+	arch_spinlock_t *lock;
+
+	preempt_disable();
+	lock_acquire_shared(&lg->lock_dep_map, 0, 0, NULL, _RET_IP_);
+	lock = this_cpu_ptr(lg->lock);
+	arch_spin_lock(lock);
+}
+EXPORT_SYMBOL(lg_local_lock);
+
+void lg_local_unlock(struct lglock *lg)
+{
+	arch_spinlock_t *lock;
+
+	lock_release(&lg->lock_dep_map, 1, _RET_IP_);
+	lock = this_cpu_ptr(lg->lock);
+	arch_spin_unlock(lock);
+	preempt_enable();
+}
+EXPORT_SYMBOL(lg_local_unlock);
+
+void lg_local_lock_cpu(struct lglock *lg, int cpu)
+{
+	arch_spinlock_t *lock;
+
+	preempt_disable();
+	lock_acquire_shared(&lg->lock_dep_map, 0, 0, NULL, _RET_IP_);
+	lock = per_cpu_ptr(lg->lock, cpu);
+	arch_spin_lock(lock);
+}
+EXPORT_SYMBOL(lg_local_lock_cpu);
+
+void lg_local_unlock_cpu(struct lglock *lg, int cpu)
+{
+	arch_spinlock_t *lock;
+
+	lock_release(&lg->lock_dep_map, 1, _RET_IP_);
+	lock = per_cpu_ptr(lg->lock, cpu);
+	arch_spin_unlock(lock);
+	preempt_enable();
+}
+EXPORT_SYMBOL(lg_local_unlock_cpu);
+
+void lg_global_lock(struct lglock *lg)
+{
+	int i;
+
+	preempt_disable();
+	lock_acquire_exclusive(&lg->lock_dep_map, 0, 0, NULL, _RET_IP_);
+	for_each_possible_cpu(i) {
+		arch_spinlock_t *lock;
+		lock = per_cpu_ptr(lg->lock, i);
+		arch_spin_lock(lock);
+	}
+}
+EXPORT_SYMBOL(lg_global_lock);
+
+void lg_global_unlock(struct lglock *lg)
+{
+	int i;
+
+	lock_release(&lg->lock_dep_map, 1, _RET_IP_);
+	for_each_possible_cpu(i) {
+		arch_spinlock_t *lock;
+		lock = per_cpu_ptr(lg->lock, i);
+		arch_spin_unlock(lock);
+	}
+	preempt_enable();
+}
+EXPORT_SYMBOL(lg_global_unlock);
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
new file mode 100644
index 000000000..aaeae885d
--- /dev/null
+++ b/kernel/locking/lockdep.c
@@ -0,0 +1,4304 @@
+/*
+ * kernel/lockdep.c
+ *
+ * Runtime locking correctness validator
+ *
+ * Started by Ingo Molnar:
+ *
+ *  Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
+ *
+ * this code maps all the lock dependencies as they occur in a live kernel
+ * and will warn about the following classes of locking bugs:
+ *
+ * - lock inversion scenarios
+ * - circular lock dependencies
+ * - hardirq/softirq safe/unsafe locking bugs
+ *
+ * Bugs are reported even if the current locking scenario does not cause
+ * any deadlock at this point.
+ *
+ * I.e. if anytime in the past two locks were taken in a different order,
+ * even if it happened for another task, even if those were different
+ * locks (but of the same class as this lock), this code will detect it.
+ *
+ * Thanks to Arjan van de Ven for coming up with the initial idea of
+ * mapping lock dependencies runtime.
+ */
+#define DISABLE_BRANCH_PROFILING
+#include <linux/mutex.h>
+#include <linux/sched.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/spinlock.h>
+#include <linux/kallsyms.h>
+#include <linux/interrupt.h>
+#include <linux/stacktrace.h>
+#include <linux/debug_locks.h>
+#include <linux/irqflags.h>
+#include <linux/utsname.h>
+#include <linux/hash.h>
+#include <linux/ftrace.h>
+#include <linux/stringify.h>
+#include <linux/bitops.h>
+#include <linux/gfp.h>
+#include <linux/kmemcheck.h>
+
+#include <asm/sections.h>
+
+#include "lockdep_internals.h"
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/lock.h>
+
+#ifdef CONFIG_PROVE_LOCKING
+int prove_locking = 1;
+module_param(prove_locking, int, 0644);
+#else
+#define prove_locking 0
+#endif
+
+#ifdef CONFIG_LOCK_STAT
+int lock_stat = 1;
+module_param(lock_stat, int, 0644);
+#else
+#define lock_stat 0
+#endif
+
+/*
+ * lockdep_lock: protects the lockdep graph, the hashes and the
+ *               class/list/hash allocators.
+ *
+ * This is one of the rare exceptions where it's justified
+ * to use a raw spinlock - we really dont want the spinlock
+ * code to recurse back into the lockdep code...
+ */
+static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
+
+static int graph_lock(void)
+{
+	arch_spin_lock(&lockdep_lock);
+	/*
+	 * Make sure that if another CPU detected a bug while
+	 * walking the graph we dont change it (while the other
+	 * CPU is busy printing out stuff with the graph lock
+	 * dropped already)
+	 */
+	if (!debug_locks) {
+		arch_spin_unlock(&lockdep_lock);
+		return 0;
+	}
+	/* prevent any recursions within lockdep from causing deadlocks */
+	current->lockdep_recursion++;
+	return 1;
+}
+
+static inline int graph_unlock(void)
+{
+	if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
+		/*
+		 * The lockdep graph lock isn't locked while we expect it to
+		 * be, we're confused now, bye!
+		 */
+		return DEBUG_LOCKS_WARN_ON(1);
+	}
+
+	current->lockdep_recursion--;
+	arch_spin_unlock(&lockdep_lock);
+	return 0;
+}
+
+/*
+ * Turn lock debugging off and return with 0 if it was off already,
+ * and also release the graph lock:
+ */
+static inline int debug_locks_off_graph_unlock(void)
+{
+	int ret = debug_locks_off();
+
+	arch_spin_unlock(&lockdep_lock);
+
+	return ret;
+}
+
+static int lockdep_initialized;
+
+unsigned long nr_list_entries;
+static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
+
+/*
+ * All data structures here are protected by the global debug_lock.
+ *
+ * Mutex key structs only get allocated, once during bootup, and never
+ * get freed - this significantly simplifies the debugging code.
+ */
+unsigned long nr_lock_classes;
+static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
+
+static inline struct lock_class *hlock_class(struct held_lock *hlock)
+{
+	if (!hlock->class_idx) {
+		/*
+		 * Someone passed in garbage, we give up.
+		 */
+		DEBUG_LOCKS_WARN_ON(1);
+		return NULL;
+	}
+	return lock_classes + hlock->class_idx - 1;
+}
+
+#ifdef CONFIG_LOCK_STAT
+static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
+		      cpu_lock_stats);
+
+static inline u64 lockstat_clock(void)
+{
+	return local_clock();
+}
+
+static int lock_point(unsigned long points[], unsigned long ip)
+{
+	int i;
+
+	for (i = 0; i < LOCKSTAT_POINTS; i++) {
+		if (points[i] == 0) {
+			points[i] = ip;
+			break;
+		}
+		if (points[i] == ip)
+			break;
+	}
+
+	return i;
+}
+
+static void lock_time_inc(struct lock_time *lt, u64 time)
+{
+	if (time > lt->max)
+		lt->max = time;
+
+	if (time < lt->min || !lt->nr)
+		lt->min = time;
+
+	lt->total += time;
+	lt->nr++;
+}
+
+static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
+{
+	if (!src->nr)
+		return;
+
+	if (src->max > dst->max)
+		dst->max = src->max;
+
+	if (src->min < dst->min || !dst->nr)
+		dst->min = src->min;
+
+	dst->total += src->total;
+	dst->nr += src->nr;
+}
+
+struct lock_class_stats lock_stats(struct lock_class *class)
+{
+	struct lock_class_stats stats;
+	int cpu, i;
+
+	memset(&stats, 0, sizeof(struct lock_class_stats));
+	for_each_possible_cpu(cpu) {
+		struct lock_class_stats *pcs =
+			&per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
+
+		for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
+			stats.contention_point[i] += pcs->contention_point[i];
+
+		for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
+			stats.contending_point[i] += pcs->contending_point[i];
+
+		lock_time_add(&pcs->read_waittime, &stats.read_waittime);
+		lock_time_add(&pcs->write_waittime, &stats.write_waittime);
+
+		lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
+		lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
+
+		for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
+			stats.bounces[i] += pcs->bounces[i];
+	}
+
+	return stats;
+}
+
+void clear_lock_stats(struct lock_class *class)
+{
+	int cpu;
+
+	for_each_possible_cpu(cpu) {
+		struct lock_class_stats *cpu_stats =
+			&per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
+
+		memset(cpu_stats, 0, sizeof(struct lock_class_stats));
+	}
+	memset(class->contention_point, 0, sizeof(class->contention_point));
+	memset(class->contending_point, 0, sizeof(class->contending_point));
+}
+
+static struct lock_class_stats *get_lock_stats(struct lock_class *class)
+{
+	return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
+}
+
+static void put_lock_stats(struct lock_class_stats *stats)
+{
+	put_cpu_var(cpu_lock_stats);
+}
+
+static void lock_release_holdtime(struct held_lock *hlock)
+{
+	struct lock_class_stats *stats;
+	u64 holdtime;
+
+	if (!lock_stat)
+		return;
+
+	holdtime = lockstat_clock() - hlock->holdtime_stamp;
+
+	stats = get_lock_stats(hlock_class(hlock));
+	if (hlock->read)
+		lock_time_inc(&stats->read_holdtime, holdtime);
+	else
+		lock_time_inc(&stats->write_holdtime, holdtime);
+	put_lock_stats(stats);
+}
+#else
+static inline void lock_release_holdtime(struct held_lock *hlock)
+{
+}
+#endif
+
+/*
+ * We keep a global list of all lock classes. The list only grows,
+ * never shrinks. The list is only accessed with the lockdep
+ * spinlock lock held.
+ */
+LIST_HEAD(all_lock_classes);
+
+/*
+ * The lockdep classes are in a hash-table as well, for fast lookup:
+ */
+#define CLASSHASH_BITS		(MAX_LOCKDEP_KEYS_BITS - 1)
+#define CLASSHASH_SIZE		(1UL << CLASSHASH_BITS)
+#define __classhashfn(key)	hash_long((unsigned long)key, CLASSHASH_BITS)
+#define classhashentry(key)	(classhash_table + __classhashfn((key)))
+
+static struct list_head classhash_table[CLASSHASH_SIZE];
+
+/*
+ * We put the lock dependency chains into a hash-table as well, to cache
+ * their existence:
+ */
+#define CHAINHASH_BITS		(MAX_LOCKDEP_CHAINS_BITS-1)
+#define CHAINHASH_SIZE		(1UL << CHAINHASH_BITS)
+#define __chainhashfn(chain)	hash_long(chain, CHAINHASH_BITS)
+#define chainhashentry(chain)	(chainhash_table + __chainhashfn((chain)))
+
+static struct list_head chainhash_table[CHAINHASH_SIZE];
+
+/*
+ * The hash key of the lock dependency chains is a hash itself too:
+ * it's a hash of all locks taken up to that lock, including that lock.
+ * It's a 64-bit hash, because it's important for the keys to be
+ * unique.
+ */
+#define iterate_chain_key(key1, key2) \
+	(((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
+	((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
+	(key2))
+
+void lockdep_off(void)
+{
+	current->lockdep_recursion++;
+}
+EXPORT_SYMBOL(lockdep_off);
+
+void lockdep_on(void)
+{
+	current->lockdep_recursion--;
+}
+EXPORT_SYMBOL(lockdep_on);
+
+/*
+ * Debugging switches:
+ */
+
+#define VERBOSE			0
+#define VERY_VERBOSE		0
+
+#if VERBOSE
+# define HARDIRQ_VERBOSE	1
+# define SOFTIRQ_VERBOSE	1
+# define RECLAIM_VERBOSE	1
+#else
+# define HARDIRQ_VERBOSE	0
+# define SOFTIRQ_VERBOSE	0
+# define RECLAIM_VERBOSE	0
+#endif
+
+#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
+/*
+ * Quick filtering for interesting events:
+ */
+static int class_filter(struct lock_class *class)
+{
+#if 0
+	/* Example */
+	if (class->name_version == 1 &&
+			!strcmp(class->name, "lockname"))
+		return 1;
+	if (class->name_version == 1 &&
+			!strcmp(class->name, "&struct->lockfield"))
+		return 1;
+#endif
+	/* Filter everything else. 1 would be to allow everything else */
+	return 0;
+}
+#endif
+
+static int verbose(struct lock_class *class)
+{
+#if VERBOSE
+	return class_filter(class);
+#endif
+	return 0;
+}
+
+/*
+ * Stack-trace: tightly packed array of stack backtrace
+ * addresses. Protected by the graph_lock.
+ */
+unsigned long nr_stack_trace_entries;
+static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
+
+static void print_lockdep_off(const char *bug_msg)
+{
+	printk(KERN_DEBUG "%s\n", bug_msg);
+	printk(KERN_DEBUG "turning off the locking correctness validator.\n");
+#ifdef CONFIG_LOCK_STAT
+	printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
+#endif
+}
+
+static int save_trace(struct stack_trace *trace)
+{
+	trace->nr_entries = 0;
+	trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
+	trace->entries = stack_trace + nr_stack_trace_entries;
+
+	trace->skip = 3;
+
+	save_stack_trace(trace);
+
+	/*
+	 * Some daft arches put -1 at the end to indicate its a full trace.
+	 *
+	 * <rant> this is buggy anyway, since it takes a whole extra entry so a
+	 * complete trace that maxes out the entries provided will be reported
+	 * as incomplete, friggin useless </rant>
+	 */
+	if (trace->nr_entries != 0 &&
+	    trace->entries[trace->nr_entries-1] == ULONG_MAX)
+		trace->nr_entries--;
+
+	trace->max_entries = trace->nr_entries;
+
+	nr_stack_trace_entries += trace->nr_entries;
+
+	if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
+		if (!debug_locks_off_graph_unlock())
+			return 0;
+
+		print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
+		dump_stack();
+
+		return 0;
+	}
+
+	return 1;
+}
+
+unsigned int nr_hardirq_chains;
+unsigned int nr_softirq_chains;
+unsigned int nr_process_chains;
+unsigned int max_lockdep_depth;
+
+#ifdef CONFIG_DEBUG_LOCKDEP
+/*
+ * We cannot printk in early bootup code. Not even early_printk()
+ * might work. So we mark any initialization errors and printk
+ * about it later on, in lockdep_info().
+ */
+static int lockdep_init_error;
+static const char *lock_init_error;
+static unsigned long lockdep_init_trace_data[20];
+static struct stack_trace lockdep_init_trace = {
+	.max_entries = ARRAY_SIZE(lockdep_init_trace_data),
+	.entries = lockdep_init_trace_data,
+};
+
+/*
+ * Various lockdep statistics:
+ */
+DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
+#endif
+
+/*
+ * Locking printouts:
+ */
+
+#define __USAGE(__STATE)						\
+	[LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W",	\
+	[LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W",		\
+	[LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
+	[LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
+
+static const char *usage_str[] =
+{
+#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
+#include "lockdep_states.h"
+#undef LOCKDEP_STATE
+	[LOCK_USED] = "INITIAL USE",
+};
+
+const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
+{
+	return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
+}
+
+static inline unsigned long lock_flag(enum lock_usage_bit bit)
+{
+	return 1UL << bit;
+}
+
+static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
+{
+	char c = '.';
+
+	if (class->usage_mask & lock_flag(bit + 2))
+		c = '+';
+	if (class->usage_mask & lock_flag(bit)) {
+		c = '-';
+		if (class->usage_mask & lock_flag(bit + 2))
+			c = '?';
+	}
+
+	return c;
+}
+
+void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
+{
+	int i = 0;
+
+#define LOCKDEP_STATE(__STATE) 						\
+	usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE);	\
+	usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
+#include "lockdep_states.h"
+#undef LOCKDEP_STATE
+
+	usage[i] = '\0';
+}
+
+static void __print_lock_name(struct lock_class *class)
+{
+	char str[KSYM_NAME_LEN];
+	const char *name;
+
+	name = class->name;
+	if (!name) {
+		name = __get_key_name(class->key, str);
+		printk("%s", name);
+	} else {
+		printk("%s", name);
+		if (class->name_version > 1)
+			printk("#%d", class->name_version);
+		if (class->subclass)
+			printk("/%d", class->subclass);
+	}
+}
+
+static void print_lock_name(struct lock_class *class)
+{
+	char usage[LOCK_USAGE_CHARS];
+
+	get_usage_chars(class, usage);
+
+	printk(" (");
+	__print_lock_name(class);
+	printk("){%s}", usage);
+}
+
+static void print_lockdep_cache(struct lockdep_map *lock)
+{
+	const char *name;
+	char str[KSYM_NAME_LEN];
+
+	name = lock->name;
+	if (!name)
+		name = __get_key_name(lock->key->subkeys, str);
+
+	printk("%s", name);
+}
+
+static void print_lock(struct held_lock *hlock)
+{
+	/*
+	 * We can be called locklessly through debug_show_all_locks() so be
+	 * extra careful, the hlock might have been released and cleared.
+	 */
+	unsigned int class_idx = hlock->class_idx;
+
+	/* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfields: */
+	barrier();
+
+	if (!class_idx || (class_idx - 1) >= MAX_LOCKDEP_KEYS) {
+		printk("<RELEASED>\n");
+		return;
+	}
+
+	print_lock_name(lock_classes + class_idx - 1);
+	printk(", at: ");
+	print_ip_sym(hlock->acquire_ip);
+}
+
+static void lockdep_print_held_locks(struct task_struct *curr)
+{
+	int i, depth = curr->lockdep_depth;
+
+	if (!depth) {
+		printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
+		return;
+	}
+	printk("%d lock%s held by %s/%d:\n",
+		depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
+
+	for (i = 0; i < depth; i++) {
+		printk(" #%d: ", i);
+		print_lock(curr->held_locks + i);
+	}
+}
+
+static void print_kernel_ident(void)
+{
+	printk("%s %.*s %s\n", init_utsname()->release,
+		(int)strcspn(init_utsname()->version, " "),
+		init_utsname()->version,
+		print_tainted());
+}
+
+static int very_verbose(struct lock_class *class)
+{
+#if VERY_VERBOSE
+	return class_filter(class);
+#endif
+	return 0;
+}
+
+/*
+ * Is this the address of a static object:
+ */
+#ifdef __KERNEL__
+static int static_obj(void *obj)
+{
+	unsigned long start = (unsigned long) &_stext,
+		      end   = (unsigned long) &_end,
+		      addr  = (unsigned long) obj;
+
+	/*
+	 * static variable?
+	 */
+	if ((addr >= start) && (addr < end))
+		return 1;
+
+	if (arch_is_kernel_data(addr))
+		return 1;
+
+	/*
+	 * in-kernel percpu var?
+	 */
+	if (is_kernel_percpu_address(addr))
+		return 1;
+
+	/*
+	 * module static or percpu var?
+	 */
+	return is_module_address(addr) || is_module_percpu_address(addr);
+}
+#endif
+
+/*
+ * To make lock name printouts unique, we calculate a unique
+ * class->name_version generation counter:
+ */
+static int count_matching_names(struct lock_class *new_class)
+{
+	struct lock_class *class;
+	int count = 0;
+
+	if (!new_class->name)
+		return 0;
+
+	list_for_each_entry_rcu(class, &all_lock_classes, lock_entry) {
+		if (new_class->key - new_class->subclass == class->key)
+			return class->name_version;
+		if (class->name && !strcmp(class->name, new_class->name))
+			count = max(count, class->name_version);
+	}
+
+	return count + 1;
+}
+
+/*
+ * Register a lock's class in the hash-table, if the class is not present
+ * yet. Otherwise we look it up. We cache the result in the lock object
+ * itself, so actual lookup of the hash should be once per lock object.
+ */
+static inline struct lock_class *
+look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
+{
+	struct lockdep_subclass_key *key;
+	struct list_head *hash_head;
+	struct lock_class *class;
+
+#ifdef CONFIG_DEBUG_LOCKDEP
+	/*
+	 * If the architecture calls into lockdep before initializing
+	 * the hashes then we'll warn about it later. (we cannot printk
+	 * right now)
+	 */
+	if (unlikely(!lockdep_initialized)) {
+		lockdep_init();
+		lockdep_init_error = 1;
+		lock_init_error = lock->name;
+		save_stack_trace(&lockdep_init_trace);
+	}
+#endif
+
+	if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
+		debug_locks_off();
+		printk(KERN_ERR
+			"BUG: looking up invalid subclass: %u\n", subclass);
+		printk(KERN_ERR
+			"turning off the locking correctness validator.\n");
+		dump_stack();
+		return NULL;
+	}
+
+	/*
+	 * Static locks do not have their class-keys yet - for them the key
+	 * is the lock object itself:
+	 */
+	if (unlikely(!lock->key))
+		lock->key = (void *)lock;
+
+	/*
+	 * NOTE: the class-key must be unique. For dynamic locks, a static
+	 * lock_class_key variable is passed in through the mutex_init()
+	 * (or spin_lock_init()) call - which acts as the key. For static
+	 * locks we use the lock object itself as the key.
+	 */
+	BUILD_BUG_ON(sizeof(struct lock_class_key) >
+			sizeof(struct lockdep_map));
+
+	key = lock->key->subkeys + subclass;
+
+	hash_head = classhashentry(key);
+
+	/*
+	 * We do an RCU walk of the hash, see lockdep_free_key_range().
+	 */
+	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+		return NULL;
+
+	list_for_each_entry_rcu(class, hash_head, hash_entry) {
+		if (class->key == key) {
+			/*
+			 * Huh! same key, different name? Did someone trample
+			 * on some memory? We're most confused.
+			 */
+			WARN_ON_ONCE(class->name != lock->name);
+			return class;
+		}
+	}
+
+	return NULL;
+}
+
+/*
+ * Register a lock's class in the hash-table, if the class is not present
+ * yet. Otherwise we look it up. We cache the result in the lock object
+ * itself, so actual lookup of the hash should be once per lock object.
+ */
+static inline struct lock_class *
+register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
+{
+	struct lockdep_subclass_key *key;
+	struct list_head *hash_head;
+	struct lock_class *class;
+
+	DEBUG_LOCKS_WARN_ON(!irqs_disabled());
+
+	class = look_up_lock_class(lock, subclass);
+	if (likely(class))
+		goto out_set_class_cache;
+
+	/*
+	 * Debug-check: all keys must be persistent!
+ 	 */
+	if (!static_obj(lock->key)) {
+		debug_locks_off();
+		printk("INFO: trying to register non-static key.\n");
+		printk("the code is fine but needs lockdep annotation.\n");
+		printk("turning off the locking correctness validator.\n");
+		dump_stack();
+
+		return NULL;
+	}
+
+	key = lock->key->subkeys + subclass;
+	hash_head = classhashentry(key);
+
+	if (!graph_lock()) {
+		return NULL;
+	}
+	/*
+	 * We have to do the hash-walk again, to avoid races
+	 * with another CPU:
+	 */
+	list_for_each_entry_rcu(class, hash_head, hash_entry) {
+		if (class->key == key)
+			goto out_unlock_set;
+	}
+
+	/*
+	 * Allocate a new key from the static array, and add it to
+	 * the hash:
+	 */
+	if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
+		if (!debug_locks_off_graph_unlock()) {
+			return NULL;
+		}
+
+		print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
+		dump_stack();
+		return NULL;
+	}
+	class = lock_classes + nr_lock_classes++;
+	debug_atomic_inc(nr_unused_locks);
+	class->key = key;
+	class->name = lock->name;
+	class->subclass = subclass;
+	INIT_LIST_HEAD(&class->lock_entry);
+	INIT_LIST_HEAD(&class->locks_before);
+	INIT_LIST_HEAD(&class->locks_after);
+	class->name_version = count_matching_names(class);
+	/*
+	 * We use RCU's safe list-add method to make
+	 * parallel walking of the hash-list safe:
+	 */
+	list_add_tail_rcu(&class->hash_entry, hash_head);
+	/*
+	 * Add it to the global list of classes:
+	 */
+	list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
+
+	if (verbose(class)) {
+		graph_unlock();
+
+		printk("\nnew class %p: %s", class->key, class->name);
+		if (class->name_version > 1)
+			printk("#%d", class->name_version);
+		printk("\n");
+		dump_stack();
+
+		if (!graph_lock()) {
+			return NULL;
+		}
+	}
+out_unlock_set:
+	graph_unlock();
+
+out_set_class_cache:
+	if (!subclass || force)
+		lock->class_cache[0] = class;
+	else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
+		lock->class_cache[subclass] = class;
+
+	/*
+	 * Hash collision, did we smoke some? We found a class with a matching
+	 * hash but the subclass -- which is hashed in -- didn't match.
+	 */
+	if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
+		return NULL;
+
+	return class;
+}
+
+#ifdef CONFIG_PROVE_LOCKING
+/*
+ * Allocate a lockdep entry. (assumes the graph_lock held, returns
+ * with NULL on failure)
+ */
+static struct lock_list *alloc_list_entry(void)
+{
+	if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
+		if (!debug_locks_off_graph_unlock())
+			return NULL;
+
+		print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
+		dump_stack();
+		return NULL;
+	}
+	return list_entries + nr_list_entries++;
+}
+
+/*
+ * Add a new dependency to the head of the list:
+ */
+static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
+			    struct list_head *head, unsigned long ip,
+			    int distance, struct stack_trace *trace)
+{
+	struct lock_list *entry;
+	/*
+	 * Lock not present yet - get a new dependency struct and
+	 * add it to the list:
+	 */
+	entry = alloc_list_entry();
+	if (!entry)
+		return 0;
+
+	entry->class = this;
+	entry->distance = distance;
+	entry->trace = *trace;
+	/*
+	 * Both allocation and removal are done under the graph lock; but
+	 * iteration is under RCU-sched; see look_up_lock_class() and
+	 * lockdep_free_key_range().
+	 */
+	list_add_tail_rcu(&entry->entry, head);
+
+	return 1;
+}
+
+/*
+ * For good efficiency of modular, we use power of 2
+ */
+#define MAX_CIRCULAR_QUEUE_SIZE		4096UL
+#define CQ_MASK				(MAX_CIRCULAR_QUEUE_SIZE-1)
+
+/*
+ * The circular_queue and helpers is used to implement the
+ * breadth-first search(BFS)algorithem, by which we can build
+ * the shortest path from the next lock to be acquired to the
+ * previous held lock if there is a circular between them.
+ */
+struct circular_queue {
+	unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
+	unsigned int  front, rear;
+};
+
+static struct circular_queue lock_cq;
+
+unsigned int max_bfs_queue_depth;
+
+static unsigned int lockdep_dependency_gen_id;
+
+static inline void __cq_init(struct circular_queue *cq)
+{
+	cq->front = cq->rear = 0;
+	lockdep_dependency_gen_id++;
+}
+
+static inline int __cq_empty(struct circular_queue *cq)
+{
+	return (cq->front == cq->rear);
+}
+
+static inline int __cq_full(struct circular_queue *cq)
+{
+	return ((cq->rear + 1) & CQ_MASK) == cq->front;
+}
+
+static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
+{
+	if (__cq_full(cq))
+		return -1;
+
+	cq->element[cq->rear] = elem;
+	cq->rear = (cq->rear + 1) & CQ_MASK;
+	return 0;
+}
+
+static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
+{
+	if (__cq_empty(cq))
+		return -1;
+
+	*elem = cq->element[cq->front];
+	cq->front = (cq->front + 1) & CQ_MASK;
+	return 0;
+}
+
+static inline unsigned int  __cq_get_elem_count(struct circular_queue *cq)
+{
+	return (cq->rear - cq->front) & CQ_MASK;
+}
+
+static inline void mark_lock_accessed(struct lock_list *lock,
+					struct lock_list *parent)
+{
+	unsigned long nr;
+
+	nr = lock - list_entries;
+	WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
+	lock->parent = parent;
+	lock->class->dep_gen_id = lockdep_dependency_gen_id;
+}
+
+static inline unsigned long lock_accessed(struct lock_list *lock)
+{
+	unsigned long nr;
+
+	nr = lock - list_entries;
+	WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
+	return lock->class->dep_gen_id == lockdep_dependency_gen_id;
+}
+
+static inline struct lock_list *get_lock_parent(struct lock_list *child)
+{
+	return child->parent;
+}
+
+static inline int get_lock_depth(struct lock_list *child)
+{
+	int depth = 0;
+	struct lock_list *parent;
+
+	while ((parent = get_lock_parent(child))) {
+		child = parent;
+		depth++;
+	}
+	return depth;
+}
+
+static int __bfs(struct lock_list *source_entry,
+		 void *data,
+		 int (*match)(struct lock_list *entry, void *data),
+		 struct lock_list **target_entry,
+		 int forward)
+{
+	struct lock_list *entry;
+	struct list_head *head;
+	struct circular_queue *cq = &lock_cq;
+	int ret = 1;
+
+	if (match(source_entry, data)) {
+		*target_entry = source_entry;
+		ret = 0;
+		goto exit;
+	}
+
+	if (forward)
+		head = &source_entry->class->locks_after;
+	else
+		head = &source_entry->class->locks_before;
+
+	if (list_empty(head))
+		goto exit;
+
+	__cq_init(cq);
+	__cq_enqueue(cq, (unsigned long)source_entry);
+
+	while (!__cq_empty(cq)) {
+		struct lock_list *lock;
+
+		__cq_dequeue(cq, (unsigned long *)&lock);
+
+		if (!lock->class) {
+			ret = -2;
+			goto exit;
+		}
+
+		if (forward)
+			head = &lock->class->locks_after;
+		else
+			head = &lock->class->locks_before;
+
+		DEBUG_LOCKS_WARN_ON(!irqs_disabled());
+
+		list_for_each_entry_rcu(entry, head, entry) {
+			if (!lock_accessed(entry)) {
+				unsigned int cq_depth;
+				mark_lock_accessed(entry, lock);
+				if (match(entry, data)) {
+					*target_entry = entry;
+					ret = 0;
+					goto exit;
+				}
+
+				if (__cq_enqueue(cq, (unsigned long)entry)) {
+					ret = -1;
+					goto exit;
+				}
+				cq_depth = __cq_get_elem_count(cq);
+				if (max_bfs_queue_depth < cq_depth)
+					max_bfs_queue_depth = cq_depth;
+			}
+		}
+	}
+exit:
+	return ret;
+}
+
+static inline int __bfs_forwards(struct lock_list *src_entry,
+			void *data,
+			int (*match)(struct lock_list *entry, void *data),
+			struct lock_list **target_entry)
+{
+	return __bfs(src_entry, data, match, target_entry, 1);
+
+}
+
+static inline int __bfs_backwards(struct lock_list *src_entry,
+			void *data,
+			int (*match)(struct lock_list *entry, void *data),
+			struct lock_list **target_entry)
+{
+	return __bfs(src_entry, data, match, target_entry, 0);
+
+}
+
+/*
+ * Recursive, forwards-direction lock-dependency checking, used for
+ * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
+ * checking.
+ */
+
+/*
+ * Print a dependency chain entry (this is only done when a deadlock
+ * has been detected):
+ */
+static noinline int
+print_circular_bug_entry(struct lock_list *target, int depth)
+{
+	if (debug_locks_silent)
+		return 0;
+	printk("\n-> #%u", depth);
+	print_lock_name(target->class);
+	printk(":\n");
+	print_stack_trace(&target->trace, 6);
+
+	return 0;
+}
+
+static void
+print_circular_lock_scenario(struct held_lock *src,
+			     struct held_lock *tgt,
+			     struct lock_list *prt)
+{
+	struct lock_class *source = hlock_class(src);
+	struct lock_class *target = hlock_class(tgt);
+	struct lock_class *parent = prt->class;
+
+	/*
+	 * A direct locking problem where unsafe_class lock is taken
+	 * directly by safe_class lock, then all we need to show
+	 * is the deadlock scenario, as it is obvious that the
+	 * unsafe lock is taken under the safe lock.
+	 *
+	 * But if there is a chain instead, where the safe lock takes
+	 * an intermediate lock (middle_class) where this lock is
+	 * not the same as the safe lock, then the lock chain is
+	 * used to describe the problem. Otherwise we would need
+	 * to show a different CPU case for each link in the chain
+	 * from the safe_class lock to the unsafe_class lock.
+	 */
+	if (parent != source) {
+		printk("Chain exists of:\n  ");
+		__print_lock_name(source);
+		printk(" --> ");
+		__print_lock_name(parent);
+		printk(" --> ");
+		__print_lock_name(target);
+		printk("\n\n");
+	}
+
+	printk(" Possible unsafe locking scenario:\n\n");
+	printk("       CPU0                    CPU1\n");
+	printk("       ----                    ----\n");
+	printk("  lock(");
+	__print_lock_name(target);
+	printk(");\n");
+	printk("                               lock(");
+	__print_lock_name(parent);
+	printk(");\n");
+	printk("                               lock(");
+	__print_lock_name(target);
+	printk(");\n");
+	printk("  lock(");
+	__print_lock_name(source);
+	printk(");\n");
+	printk("\n *** DEADLOCK ***\n\n");
+}
+
+/*
+ * When a circular dependency is detected, print the
+ * header first:
+ */
+static noinline int
+print_circular_bug_header(struct lock_list *entry, unsigned int depth,
+			struct held_lock *check_src,
+			struct held_lock *check_tgt)
+{
+	struct task_struct *curr = current;
+
+	if (debug_locks_silent)
+		return 0;
+
+	printk("\n");
+	printk("======================================================\n");
+	printk("[ INFO: possible circular locking dependency detected ]\n");
+	print_kernel_ident();
+	printk("-------------------------------------------------------\n");
+	printk("%s/%d is trying to acquire lock:\n",
+		curr->comm, task_pid_nr(curr));
+	print_lock(check_src);
+	printk("\nbut task is already holding lock:\n");
+	print_lock(check_tgt);
+	printk("\nwhich lock already depends on the new lock.\n\n");
+	printk("\nthe existing dependency chain (in reverse order) is:\n");
+
+	print_circular_bug_entry(entry, depth);
+
+	return 0;
+}
+
+static inline int class_equal(struct lock_list *entry, void *data)
+{
+	return entry->class == data;
+}
+
+static noinline int print_circular_bug(struct lock_list *this,
+				struct lock_list *target,
+				struct held_lock *check_src,
+				struct held_lock *check_tgt)
+{
+	struct task_struct *curr = current;
+	struct lock_list *parent;
+	struct lock_list *first_parent;
+	int depth;
+
+	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
+		return 0;
+
+	if (!save_trace(&this->trace))
+		return 0;
+
+	depth = get_lock_depth(target);
+
+	print_circular_bug_header(target, depth, check_src, check_tgt);
+
+	parent = get_lock_parent(target);
+	first_parent = parent;
+
+	while (parent) {
+		print_circular_bug_entry(parent, --depth);
+		parent = get_lock_parent(parent);
+	}
+
+	printk("\nother info that might help us debug this:\n\n");
+	print_circular_lock_scenario(check_src, check_tgt,
+				     first_parent);
+
+	lockdep_print_held_locks(curr);
+
+	printk("\nstack backtrace:\n");
+	dump_stack();
+
+	return 0;
+}
+
+static noinline int print_bfs_bug(int ret)
+{
+	if (!debug_locks_off_graph_unlock())
+		return 0;
+
+	/*
+	 * Breadth-first-search failed, graph got corrupted?
+	 */
+	WARN(1, "lockdep bfs error:%d\n", ret);
+
+	return 0;
+}
+
+static int noop_count(struct lock_list *entry, void *data)
+{
+	(*(unsigned long *)data)++;
+	return 0;
+}
+
+static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
+{
+	unsigned long  count = 0;
+	struct lock_list *uninitialized_var(target_entry);
+
+	__bfs_forwards(this, (void *)&count, noop_count, &target_entry);
+
+	return count;
+}
+unsigned long lockdep_count_forward_deps(struct lock_class *class)
+{
+	unsigned long ret, flags;
+	struct lock_list this;
+
+	this.parent = NULL;
+	this.class = class;
+
+	local_irq_save(flags);
+	arch_spin_lock(&lockdep_lock);
+	ret = __lockdep_count_forward_deps(&this);
+	arch_spin_unlock(&lockdep_lock);
+	local_irq_restore(flags);
+
+	return ret;
+}
+
+static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
+{
+	unsigned long  count = 0;
+	struct lock_list *uninitialized_var(target_entry);
+
+	__bfs_backwards(this, (void *)&count, noop_count, &target_entry);
+
+	return count;
+}
+
+unsigned long lockdep_count_backward_deps(struct lock_class *class)
+{
+	unsigned long ret, flags;
+	struct lock_list this;
+
+	this.parent = NULL;
+	this.class = class;
+
+	local_irq_save(flags);
+	arch_spin_lock(&lockdep_lock);
+	ret = __lockdep_count_backward_deps(&this);
+	arch_spin_unlock(&lockdep_lock);
+	local_irq_restore(flags);
+
+	return ret;
+}
+
+/*
+ * Prove that the dependency graph starting at <entry> can not
+ * lead to <target>. Print an error and return 0 if it does.
+ */
+static noinline int
+check_noncircular(struct lock_list *root, struct lock_class *target,
+		struct lock_list **target_entry)
+{
+	int result;
+
+	debug_atomic_inc(nr_cyclic_checks);
+
+	result = __bfs_forwards(root, target, class_equal, target_entry);
+
+	return result;
+}
+
+#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
+/*
+ * Forwards and backwards subgraph searching, for the purposes of
+ * proving that two subgraphs can be connected by a new dependency
+ * without creating any illegal irq-safe -> irq-unsafe lock dependency.
+ */
+
+static inline int usage_match(struct lock_list *entry, void *bit)
+{
+	return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
+}
+
+
+
+/*
+ * Find a node in the forwards-direction dependency sub-graph starting
+ * at @root->class that matches @bit.
+ *
+ * Return 0 if such a node exists in the subgraph, and put that node
+ * into *@target_entry.
+ *
+ * Return 1 otherwise and keep *@target_entry unchanged.
+ * Return <0 on error.
+ */
+static int
+find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
+			struct lock_list **target_entry)
+{
+	int result;
+
+	debug_atomic_inc(nr_find_usage_forwards_checks);
+
+	result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
+
+	return result;
+}
+
+/*
+ * Find a node in the backwards-direction dependency sub-graph starting
+ * at @root->class that matches @bit.
+ *
+ * Return 0 if such a node exists in the subgraph, and put that node
+ * into *@target_entry.
+ *
+ * Return 1 otherwise and keep *@target_entry unchanged.
+ * Return <0 on error.
+ */
+static int
+find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
+			struct lock_list **target_entry)
+{
+	int result;
+
+	debug_atomic_inc(nr_find_usage_backwards_checks);
+
+	result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
+
+	return result;
+}
+
+static void print_lock_class_header(struct lock_class *class, int depth)
+{
+	int bit;
+
+	printk("%*s->", depth, "");
+	print_lock_name(class);
+	printk(" ops: %lu", class->ops);
+	printk(" {\n");
+
+	for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
+		if (class->usage_mask & (1 << bit)) {
+			int len = depth;
+
+			len += printk("%*s   %s", depth, "", usage_str[bit]);
+			len += printk(" at:\n");
+			print_stack_trace(class->usage_traces + bit, len);
+		}
+	}
+	printk("%*s }\n", depth, "");
+
+	printk("%*s ... key      at: ",depth,"");
+	print_ip_sym((unsigned long)class->key);
+}
+
+/*
+ * printk the shortest lock dependencies from @start to @end in reverse order:
+ */
+static void __used
+print_shortest_lock_dependencies(struct lock_list *leaf,
+				struct lock_list *root)
+{
+	struct lock_list *entry = leaf;
+	int depth;
+
+	/*compute depth from generated tree by BFS*/
+	depth = get_lock_depth(leaf);
+
+	do {
+		print_lock_class_header(entry->class, depth);
+		printk("%*s ... acquired at:\n", depth, "");
+		print_stack_trace(&entry->trace, 2);
+		printk("\n");
+
+		if (depth == 0 && (entry != root)) {
+			printk("lockdep:%s bad path found in chain graph\n", __func__);
+			break;
+		}
+
+		entry = get_lock_parent(entry);
+		depth--;
+	} while (entry && (depth >= 0));
+
+	return;
+}
+
+static void
+print_irq_lock_scenario(struct lock_list *safe_entry,
+			struct lock_list *unsafe_entry,
+			struct lock_class *prev_class,
+			struct lock_class *next_class)
+{
+	struct lock_class *safe_class = safe_entry->class;
+	struct lock_class *unsafe_class = unsafe_entry->class;
+	struct lock_class *middle_class = prev_class;
+
+	if (middle_class == safe_class)
+		middle_class = next_class;
+
+	/*
+	 * A direct locking problem where unsafe_class lock is taken
+	 * directly by safe_class lock, then all we need to show
+	 * is the deadlock scenario, as it is obvious that the
+	 * unsafe lock is taken under the safe lock.
+	 *
+	 * But if there is a chain instead, where the safe lock takes
+	 * an intermediate lock (middle_class) where this lock is
+	 * not the same as the safe lock, then the lock chain is
+	 * used to describe the problem. Otherwise we would need
+	 * to show a different CPU case for each link in the chain
+	 * from the safe_class lock to the unsafe_class lock.
+	 */
+	if (middle_class != unsafe_class) {
+		printk("Chain exists of:\n  ");
+		__print_lock_name(safe_class);
+		printk(" --> ");
+		__print_lock_name(middle_class);
+		printk(" --> ");
+		__print_lock_name(unsafe_class);
+		printk("\n\n");
+	}
+
+	printk(" Possible interrupt unsafe locking scenario:\n\n");
+	printk("       CPU0                    CPU1\n");
+	printk("       ----                    ----\n");
+	printk("  lock(");
+	__print_lock_name(unsafe_class);
+	printk(");\n");
+	printk("                               local_irq_disable();\n");
+	printk("                               lock(");
+	__print_lock_name(safe_class);
+	printk(");\n");
+	printk("                               lock(");
+	__print_lock_name(middle_class);
+	printk(");\n");
+	printk("  <Interrupt>\n");
+	printk("    lock(");
+	__print_lock_name(safe_class);
+	printk(");\n");
+	printk("\n *** DEADLOCK ***\n\n");
+}
+
+static int
+print_bad_irq_dependency(struct task_struct *curr,
+			 struct lock_list *prev_root,
+			 struct lock_list *next_root,
+			 struct lock_list *backwards_entry,
+			 struct lock_list *forwards_entry,
+			 struct held_lock *prev,
+			 struct held_lock *next,
+			 enum lock_usage_bit bit1,
+			 enum lock_usage_bit bit2,
+			 const char *irqclass)
+{
+	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
+		return 0;
+
+	printk("\n");
+	printk("======================================================\n");
+	printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
+		irqclass, irqclass);
+	print_kernel_ident();
+	printk("------------------------------------------------------\n");
+	printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
+		curr->comm, task_pid_nr(curr),
+		curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
+		curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
+		curr->hardirqs_enabled,
+		curr->softirqs_enabled);
+	print_lock(next);
+
+	printk("\nand this task is already holding:\n");
+	print_lock(prev);
+	printk("which would create a new lock dependency:\n");
+	print_lock_name(hlock_class(prev));
+	printk(" ->");
+	print_lock_name(hlock_class(next));
+	printk("\n");
+
+	printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
+		irqclass);
+	print_lock_name(backwards_entry->class);
+	printk("\n... which became %s-irq-safe at:\n", irqclass);
+
+	print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
+
+	printk("\nto a %s-irq-unsafe lock:\n", irqclass);
+	print_lock_name(forwards_entry->class);
+	printk("\n... which became %s-irq-unsafe at:\n", irqclass);
+	printk("...");
+
+	print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
+
+	printk("\nother info that might help us debug this:\n\n");
+	print_irq_lock_scenario(backwards_entry, forwards_entry,
+				hlock_class(prev), hlock_class(next));
+
+	lockdep_print_held_locks(curr);
+
+	printk("\nthe dependencies between %s-irq-safe lock", irqclass);
+	printk(" and the holding lock:\n");
+	if (!save_trace(&prev_root->trace))
+		return 0;
+	print_shortest_lock_dependencies(backwards_entry, prev_root);
+
+	printk("\nthe dependencies between the lock to be acquired");
+	printk(" and %s-irq-unsafe lock:\n", irqclass);
+	if (!save_trace(&next_root->trace))
+		return 0;
+	print_shortest_lock_dependencies(forwards_entry, next_root);
+
+	printk("\nstack backtrace:\n");
+	dump_stack();
+
+	return 0;
+}
+
+static int
+check_usage(struct task_struct *curr, struct held_lock *prev,
+	    struct held_lock *next, enum lock_usage_bit bit_backwards,
+	    enum lock_usage_bit bit_forwards, const char *irqclass)
+{
+	int ret;
+	struct lock_list this, that;
+	struct lock_list *uninitialized_var(target_entry);
+	struct lock_list *uninitialized_var(target_entry1);
+
+	this.parent = NULL;
+
+	this.class = hlock_class(prev);
+	ret = find_usage_backwards(&this, bit_backwards, &target_entry);
+	if (ret < 0)
+		return print_bfs_bug(ret);
+	if (ret == 1)
+		return ret;
+
+	that.parent = NULL;
+	that.class = hlock_class(next);
+	ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
+	if (ret < 0)
+		return print_bfs_bug(ret);
+	if (ret == 1)
+		return ret;
+
+	return print_bad_irq_dependency(curr, &this, &that,
+			target_entry, target_entry1,
+			prev, next,
+			bit_backwards, bit_forwards, irqclass);
+}
+
+static const char *state_names[] = {
+#define LOCKDEP_STATE(__STATE) \
+	__stringify(__STATE),
+#include "lockdep_states.h"
+#undef LOCKDEP_STATE
+};
+
+static const char *state_rnames[] = {
+#define LOCKDEP_STATE(__STATE) \
+	__stringify(__STATE)"-READ",
+#include "lockdep_states.h"
+#undef LOCKDEP_STATE
+};
+
+static inline const char *state_name(enum lock_usage_bit bit)
+{
+	return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
+}
+
+static int exclusive_bit(int new_bit)
+{
+	/*
+	 * USED_IN
+	 * USED_IN_READ
+	 * ENABLED
+	 * ENABLED_READ
+	 *
+	 * bit 0 - write/read
+	 * bit 1 - used_in/enabled
+	 * bit 2+  state
+	 */
+
+	int state = new_bit & ~3;
+	int dir = new_bit & 2;
+
+	/*
+	 * keep state, bit flip the direction and strip read.
+	 */
+	return state | (dir ^ 2);
+}
+
+static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
+			   struct held_lock *next, enum lock_usage_bit bit)
+{
+	/*
+	 * Prove that the new dependency does not connect a hardirq-safe
+	 * lock with a hardirq-unsafe lock - to achieve this we search
+	 * the backwards-subgraph starting at <prev>, and the
+	 * forwards-subgraph starting at <next>:
+	 */
+	if (!check_usage(curr, prev, next, bit,
+			   exclusive_bit(bit), state_name(bit)))
+		return 0;
+
+	bit++; /* _READ */
+
+	/*
+	 * Prove that the new dependency does not connect a hardirq-safe-read
+	 * lock with a hardirq-unsafe lock - to achieve this we search
+	 * the backwards-subgraph starting at <prev>, and the
+	 * forwards-subgraph starting at <next>:
+	 */
+	if (!check_usage(curr, prev, next, bit,
+			   exclusive_bit(bit), state_name(bit)))
+		return 0;
+
+	return 1;
+}
+
+static int
+check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
+		struct held_lock *next)
+{
+#define LOCKDEP_STATE(__STATE)						\
+	if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE))	\
+		return 0;
+#include "lockdep_states.h"
+#undef LOCKDEP_STATE
+
+	return 1;
+}
+
+static void inc_chains(void)
+{
+	if (current->hardirq_context)
+		nr_hardirq_chains++;
+	else {
+		if (current->softirq_context)
+			nr_softirq_chains++;
+		else
+			nr_process_chains++;
+	}
+}
+
+#else
+
+static inline int
+check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
+		struct held_lock *next)
+{
+	return 1;
+}
+
+static inline void inc_chains(void)
+{
+	nr_process_chains++;
+}
+
+#endif
+
+static void
+print_deadlock_scenario(struct held_lock *nxt,
+			     struct held_lock *prv)
+{
+	struct lock_class *next = hlock_class(nxt);
+	struct lock_class *prev = hlock_class(prv);
+
+	printk(" Possible unsafe locking scenario:\n\n");
+	printk("       CPU0\n");
+	printk("       ----\n");
+	printk("  lock(");
+	__print_lock_name(prev);
+	printk(");\n");
+	printk("  lock(");
+	__print_lock_name(next);
+	printk(");\n");
+	printk("\n *** DEADLOCK ***\n\n");
+	printk(" May be due to missing lock nesting notation\n\n");
+}
+
+static int
+print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
+		   struct held_lock *next)
+{
+	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
+		return 0;
+
+	printk("\n");
+	printk("=============================================\n");
+	printk("[ INFO: possible recursive locking detected ]\n");
+	print_kernel_ident();
+	printk("---------------------------------------------\n");
+	printk("%s/%d is trying to acquire lock:\n",
+		curr->comm, task_pid_nr(curr));
+	print_lock(next);
+	printk("\nbut task is already holding lock:\n");
+	print_lock(prev);
+
+	printk("\nother info that might help us debug this:\n");
+	print_deadlock_scenario(next, prev);
+	lockdep_print_held_locks(curr);
+
+	printk("\nstack backtrace:\n");
+	dump_stack();
+
+	return 0;
+}
+
+/*
+ * Check whether we are holding such a class already.
+ *
+ * (Note that this has to be done separately, because the graph cannot
+ * detect such classes of deadlocks.)
+ *
+ * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
+ */
+static int
+check_deadlock(struct task_struct *curr, struct held_lock *next,
+	       struct lockdep_map *next_instance, int read)
+{
+	struct held_lock *prev;
+	struct held_lock *nest = NULL;
+	int i;
+
+	for (i = 0; i < curr->lockdep_depth; i++) {
+		prev = curr->held_locks + i;
+
+		if (prev->instance == next->nest_lock)
+			nest = prev;
+
+		if (hlock_class(prev) != hlock_class(next))
+			continue;
+
+		/*
+		 * Allow read-after-read recursion of the same
+		 * lock class (i.e. read_lock(lock)+read_lock(lock)):
+		 */
+		if ((read == 2) && prev->read)
+			return 2;
+
+		/*
+		 * We're holding the nest_lock, which serializes this lock's
+		 * nesting behaviour.
+		 */
+		if (nest)
+			return 2;
+
+		return print_deadlock_bug(curr, prev, next);
+	}
+	return 1;
+}
+
+/*
+ * There was a chain-cache miss, and we are about to add a new dependency
+ * to a previous lock. We recursively validate the following rules:
+ *
+ *  - would the adding of the <prev> -> <next> dependency create a
+ *    circular dependency in the graph? [== circular deadlock]
+ *
+ *  - does the new prev->next dependency connect any hardirq-safe lock
+ *    (in the full backwards-subgraph starting at <prev>) with any
+ *    hardirq-unsafe lock (in the full forwards-subgraph starting at
+ *    <next>)? [== illegal lock inversion with hardirq contexts]
+ *
+ *  - does the new prev->next dependency connect any softirq-safe lock
+ *    (in the full backwards-subgraph starting at <prev>) with any
+ *    softirq-unsafe lock (in the full forwards-subgraph starting at
+ *    <next>)? [== illegal lock inversion with softirq contexts]
+ *
+ * any of these scenarios could lead to a deadlock.
+ *
+ * Then if all the validations pass, we add the forwards and backwards
+ * dependency.
+ */
+static int
+check_prev_add(struct task_struct *curr, struct held_lock *prev,
+	       struct held_lock *next, int distance, int trylock_loop)
+{
+	struct lock_list *entry;
+	int ret;
+	struct lock_list this;
+	struct lock_list *uninitialized_var(target_entry);
+	/*
+	 * Static variable, serialized by the graph_lock().
+	 *
+	 * We use this static variable to save the stack trace in case
+	 * we call into this function multiple times due to encountering
+	 * trylocks in the held lock stack.
+	 */
+	static struct stack_trace trace;
+
+	/*
+	 * Prove that the new <prev> -> <next> dependency would not
+	 * create a circular dependency in the graph. (We do this by
+	 * forward-recursing into the graph starting at <next>, and
+	 * checking whether we can reach <prev>.)
+	 *
+	 * We are using global variables to control the recursion, to
+	 * keep the stackframe size of the recursive functions low:
+	 */
+	this.class = hlock_class(next);
+	this.parent = NULL;
+	ret = check_noncircular(&this, hlock_class(prev), &target_entry);
+	if (unlikely(!ret))
+		return print_circular_bug(&this, target_entry, next, prev);
+	else if (unlikely(ret < 0))
+		return print_bfs_bug(ret);
+
+	if (!check_prev_add_irq(curr, prev, next))
+		return 0;
+
+	/*
+	 * For recursive read-locks we do all the dependency checks,
+	 * but we dont store read-triggered dependencies (only
+	 * write-triggered dependencies). This ensures that only the
+	 * write-side dependencies matter, and that if for example a
+	 * write-lock never takes any other locks, then the reads are
+	 * equivalent to a NOP.
+	 */
+	if (next->read == 2 || prev->read == 2)
+		return 1;
+	/*
+	 * Is the <prev> -> <next> dependency already present?
+	 *
+	 * (this may occur even though this is a new chain: consider
+	 *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
+	 *  chains - the second one will be new, but L1 already has
+	 *  L2 added to its dependency list, due to the first chain.)
+	 */
+	list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
+		if (entry->class == hlock_class(next)) {
+			if (distance == 1)
+				entry->distance = 1;
+			return 2;
+		}
+	}
+
+	if (!trylock_loop && !save_trace(&trace))
+		return 0;
+
+	/*
+	 * Ok, all validations passed, add the new lock
+	 * to the previous lock's dependency list:
+	 */
+	ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
+			       &hlock_class(prev)->locks_after,
+			       next->acquire_ip, distance, &trace);
+
+	if (!ret)
+		return 0;
+
+	ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
+			       &hlock_class(next)->locks_before,
+			       next->acquire_ip, distance, &trace);
+	if (!ret)
+		return 0;
+
+	/*
+	 * Debugging printouts:
+	 */
+	if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
+		graph_unlock();
+		printk("\n new dependency: ");
+		print_lock_name(hlock_class(prev));
+		printk(" => ");
+		print_lock_name(hlock_class(next));
+		printk("\n");
+		dump_stack();
+		return graph_lock();
+	}
+	return 1;
+}
+
+/*
+ * Add the dependency to all directly-previous locks that are 'relevant'.
+ * The ones that are relevant are (in increasing distance from curr):
+ * all consecutive trylock entries and the final non-trylock entry - or
+ * the end of this context's lock-chain - whichever comes first.
+ */
+static int
+check_prevs_add(struct task_struct *curr, struct held_lock *next)
+{
+	int depth = curr->lockdep_depth;
+	int trylock_loop = 0;
+	struct held_lock *hlock;
+
+	/*
+	 * Debugging checks.
+	 *
+	 * Depth must not be zero for a non-head lock:
+	 */
+	if (!depth)
+		goto out_bug;
+	/*
+	 * At least two relevant locks must exist for this
+	 * to be a head:
+	 */
+	if (curr->held_locks[depth].irq_context !=
+			curr->held_locks[depth-1].irq_context)
+		goto out_bug;
+
+	for (;;) {
+		int distance = curr->lockdep_depth - depth + 1;
+		hlock = curr->held_locks + depth - 1;
+		/*
+		 * Only non-recursive-read entries get new dependencies
+		 * added:
+		 */
+		if (hlock->read != 2 && hlock->check) {
+			if (!check_prev_add(curr, hlock, next,
+						distance, trylock_loop))
+				return 0;
+			/*
+			 * Stop after the first non-trylock entry,
+			 * as non-trylock entries have added their
+			 * own direct dependencies already, so this
+			 * lock is connected to them indirectly:
+			 */
+			if (!hlock->trylock)
+				break;
+		}
+		depth--;
+		/*
+		 * End of lock-stack?
+		 */
+		if (!depth)
+			break;
+		/*
+		 * Stop the search if we cross into another context:
+		 */
+		if (curr->held_locks[depth].irq_context !=
+				curr->held_locks[depth-1].irq_context)
+			break;
+		trylock_loop = 1;
+	}
+	return 1;
+out_bug:
+	if (!debug_locks_off_graph_unlock())
+		return 0;
+
+	/*
+	 * Clearly we all shouldn't be here, but since we made it we
+	 * can reliable say we messed up our state. See the above two
+	 * gotos for reasons why we could possibly end up here.
+	 */
+	WARN_ON(1);
+
+	return 0;
+}
+
+unsigned long nr_lock_chains;
+struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
+int nr_chain_hlocks;
+static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
+
+struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
+{
+	return lock_classes + chain_hlocks[chain->base + i];
+}
+
+/*
+ * Look up a dependency chain. If the key is not present yet then
+ * add it and return 1 - in this case the new dependency chain is
+ * validated. If the key is already hashed, return 0.
+ * (On return with 1 graph_lock is held.)
+ */
+static inline int lookup_chain_cache(struct task_struct *curr,
+				     struct held_lock *hlock,
+				     u64 chain_key)
+{
+	struct lock_class *class = hlock_class(hlock);
+	struct list_head *hash_head = chainhashentry(chain_key);
+	struct lock_chain *chain;
+	struct held_lock *hlock_curr;
+	int i, j;
+
+	/*
+	 * We might need to take the graph lock, ensure we've got IRQs
+	 * disabled to make this an IRQ-safe lock.. for recursion reasons
+	 * lockdep won't complain about its own locking errors.
+	 */
+	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+		return 0;
+	/*
+	 * We can walk it lock-free, because entries only get added
+	 * to the hash:
+	 */
+	list_for_each_entry_rcu(chain, hash_head, entry) {
+		if (chain->chain_key == chain_key) {
+cache_hit:
+			debug_atomic_inc(chain_lookup_hits);
+			if (very_verbose(class))
+				printk("\nhash chain already cached, key: "
+					"%016Lx tail class: [%p] %s\n",
+					(unsigned long long)chain_key,
+					class->key, class->name);
+			return 0;
+		}
+	}
+	if (very_verbose(class))
+		printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
+			(unsigned long long)chain_key, class->key, class->name);
+	/*
+	 * Allocate a new chain entry from the static array, and add
+	 * it to the hash:
+	 */
+	if (!graph_lock())
+		return 0;
+	/*
+	 * We have to walk the chain again locked - to avoid duplicates:
+	 */
+	list_for_each_entry(chain, hash_head, entry) {
+		if (chain->chain_key == chain_key) {
+			graph_unlock();
+			goto cache_hit;
+		}
+	}
+	if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
+		if (!debug_locks_off_graph_unlock())
+			return 0;
+
+		print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
+		dump_stack();
+		return 0;
+	}
+	chain = lock_chains + nr_lock_chains++;
+	chain->chain_key = chain_key;
+	chain->irq_context = hlock->irq_context;
+	/* Find the first held_lock of current chain */
+	for (i = curr->lockdep_depth - 1; i >= 0; i--) {
+		hlock_curr = curr->held_locks + i;
+		if (hlock_curr->irq_context != hlock->irq_context)
+			break;
+	}
+	i++;
+	chain->depth = curr->lockdep_depth + 1 - i;
+	if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
+		chain->base = nr_chain_hlocks;
+		nr_chain_hlocks += chain->depth;
+		for (j = 0; j < chain->depth - 1; j++, i++) {
+			int lock_id = curr->held_locks[i].class_idx - 1;
+			chain_hlocks[chain->base + j] = lock_id;
+		}
+		chain_hlocks[chain->base + j] = class - lock_classes;
+	}
+	list_add_tail_rcu(&chain->entry, hash_head);
+	debug_atomic_inc(chain_lookup_misses);
+	inc_chains();
+
+	return 1;
+}
+
+static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
+		struct held_lock *hlock, int chain_head, u64 chain_key)
+{
+	/*
+	 * Trylock needs to maintain the stack of held locks, but it
+	 * does not add new dependencies, because trylock can be done
+	 * in any order.
+	 *
+	 * We look up the chain_key and do the O(N^2) check and update of
+	 * the dependencies only if this is a new dependency chain.
+	 * (If lookup_chain_cache() returns with 1 it acquires
+	 * graph_lock for us)
+	 */
+	if (!hlock->trylock && hlock->check &&
+	    lookup_chain_cache(curr, hlock, chain_key)) {
+		/*
+		 * Check whether last held lock:
+		 *
+		 * - is irq-safe, if this lock is irq-unsafe
+		 * - is softirq-safe, if this lock is hardirq-unsafe
+		 *
+		 * And check whether the new lock's dependency graph
+		 * could lead back to the previous lock.
+		 *
+		 * any of these scenarios could lead to a deadlock. If
+		 * All validations
+		 */
+		int ret = check_deadlock(curr, hlock, lock, hlock->read);
+
+		if (!ret)
+			return 0;
+		/*
+		 * Mark recursive read, as we jump over it when
+		 * building dependencies (just like we jump over
+		 * trylock entries):
+		 */
+		if (ret == 2)
+			hlock->read = 2;
+		/*
+		 * Add dependency only if this lock is not the head
+		 * of the chain, and if it's not a secondary read-lock:
+		 */
+		if (!chain_head && ret != 2)
+			if (!check_prevs_add(curr, hlock))
+				return 0;
+		graph_unlock();
+	} else
+		/* after lookup_chain_cache(): */
+		if (unlikely(!debug_locks))
+			return 0;
+
+	return 1;
+}
+#else
+static inline int validate_chain(struct task_struct *curr,
+	       	struct lockdep_map *lock, struct held_lock *hlock,
+		int chain_head, u64 chain_key)
+{
+	return 1;
+}
+#endif
+
+/*
+ * We are building curr_chain_key incrementally, so double-check
+ * it from scratch, to make sure that it's done correctly:
+ */
+static void check_chain_key(struct task_struct *curr)
+{
+#ifdef CONFIG_DEBUG_LOCKDEP
+	struct held_lock *hlock, *prev_hlock = NULL;
+	unsigned int i, id;
+	u64 chain_key = 0;
+
+	for (i = 0; i < curr->lockdep_depth; i++) {
+		hlock = curr->held_locks + i;
+		if (chain_key != hlock->prev_chain_key) {
+			debug_locks_off();
+			/*
+			 * We got mighty confused, our chain keys don't match
+			 * with what we expect, someone trample on our task state?
+			 */
+			WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
+				curr->lockdep_depth, i,
+				(unsigned long long)chain_key,
+				(unsigned long long)hlock->prev_chain_key);
+			return;
+		}
+		id = hlock->class_idx - 1;
+		/*
+		 * Whoops ran out of static storage again?
+		 */
+		if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
+			return;
+
+		if (prev_hlock && (prev_hlock->irq_context !=
+							hlock->irq_context))
+			chain_key = 0;
+		chain_key = iterate_chain_key(chain_key, id);
+		prev_hlock = hlock;
+	}
+	if (chain_key != curr->curr_chain_key) {
+		debug_locks_off();
+		/*
+		 * More smoking hash instead of calculating it, damn see these
+		 * numbers float.. I bet that a pink elephant stepped on my memory.
+		 */
+		WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
+			curr->lockdep_depth, i,
+			(unsigned long long)chain_key,
+			(unsigned long long)curr->curr_chain_key);
+	}
+#endif
+}
+
+static void
+print_usage_bug_scenario(struct held_lock *lock)
+{
+	struct lock_class *class = hlock_class(lock);
+
+	printk(" Possible unsafe locking scenario:\n\n");
+	printk("       CPU0\n");
+	printk("       ----\n");
+	printk("  lock(");
+	__print_lock_name(class);
+	printk(");\n");
+	printk("  <Interrupt>\n");
+	printk("    lock(");
+	__print_lock_name(class);
+	printk(");\n");
+	printk("\n *** DEADLOCK ***\n\n");
+}
+
+static int
+print_usage_bug(struct task_struct *curr, struct held_lock *this,
+		enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
+{
+	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
+		return 0;
+
+	printk("\n");
+	printk("=================================\n");
+	printk("[ INFO: inconsistent lock state ]\n");
+	print_kernel_ident();
+	printk("---------------------------------\n");
+
+	printk("inconsistent {%s} -> {%s} usage.\n",
+		usage_str[prev_bit], usage_str[new_bit]);
+
+	printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
+		curr->comm, task_pid_nr(curr),
+		trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
+		trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
+		trace_hardirqs_enabled(curr),
+		trace_softirqs_enabled(curr));
+	print_lock(this);
+
+	printk("{%s} state was registered at:\n", usage_str[prev_bit]);
+	print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
+
+	print_irqtrace_events(curr);
+	printk("\nother info that might help us debug this:\n");
+	print_usage_bug_scenario(this);
+
+	lockdep_print_held_locks(curr);
+
+	printk("\nstack backtrace:\n");
+	dump_stack();
+
+	return 0;
+}
+
+/*
+ * Print out an error if an invalid bit is set:
+ */
+static inline int
+valid_state(struct task_struct *curr, struct held_lock *this,
+	    enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
+{
+	if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
+		return print_usage_bug(curr, this, bad_bit, new_bit);
+	return 1;
+}
+
+static int mark_lock(struct task_struct *curr, struct held_lock *this,
+		     enum lock_usage_bit new_bit);
+
+#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
+
+/*
+ * print irq inversion bug:
+ */
+static int
+print_irq_inversion_bug(struct task_struct *curr,
+			struct lock_list *root, struct lock_list *other,
+			struct held_lock *this, int forwards,
+			const char *irqclass)
+{
+	struct lock_list *entry = other;
+	struct lock_list *middle = NULL;
+	int depth;
+
+	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
+		return 0;
+
+	printk("\n");
+	printk("=========================================================\n");
+	printk("[ INFO: possible irq lock inversion dependency detected ]\n");
+	print_kernel_ident();
+	printk("---------------------------------------------------------\n");
+	printk("%s/%d just changed the state of lock:\n",
+		curr->comm, task_pid_nr(curr));
+	print_lock(this);
+	if (forwards)
+		printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
+	else
+		printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
+	print_lock_name(other->class);
+	printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
+
+	printk("\nother info that might help us debug this:\n");
+
+	/* Find a middle lock (if one exists) */
+	depth = get_lock_depth(other);
+	do {
+		if (depth == 0 && (entry != root)) {
+			printk("lockdep:%s bad path found in chain graph\n", __func__);
+			break;
+		}
+		middle = entry;
+		entry = get_lock_parent(entry);
+		depth--;
+	} while (entry && entry != root && (depth >= 0));
+	if (forwards)
+		print_irq_lock_scenario(root, other,
+			middle ? middle->class : root->class, other->class);
+	else
+		print_irq_lock_scenario(other, root,
+			middle ? middle->class : other->class, root->class);
+
+	lockdep_print_held_locks(curr);
+
+	printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
+	if (!save_trace(&root->trace))
+		return 0;
+	print_shortest_lock_dependencies(other, root);
+
+	printk("\nstack backtrace:\n");
+	dump_stack();
+
+	return 0;
+}
+
+/*
+ * Prove that in the forwards-direction subgraph starting at <this>
+ * there is no lock matching <mask>:
+ */
+static int
+check_usage_forwards(struct task_struct *curr, struct held_lock *this,
+		     enum lock_usage_bit bit, const char *irqclass)
+{
+	int ret;
+	struct lock_list root;
+	struct lock_list *uninitialized_var(target_entry);
+
+	root.parent = NULL;
+	root.class = hlock_class(this);
+	ret = find_usage_forwards(&root, bit, &target_entry);
+	if (ret < 0)
+		return print_bfs_bug(ret);
+	if (ret == 1)
+		return ret;
+
+	return print_irq_inversion_bug(curr, &root, target_entry,
+					this, 1, irqclass);
+}
+
+/*
+ * Prove that in the backwards-direction subgraph starting at <this>
+ * there is no lock matching <mask>:
+ */
+static int
+check_usage_backwards(struct task_struct *curr, struct held_lock *this,
+		      enum lock_usage_bit bit, const char *irqclass)
+{
+	int ret;
+	struct lock_list root;
+	struct lock_list *uninitialized_var(target_entry);
+
+	root.parent = NULL;
+	root.class = hlock_class(this);
+	ret = find_usage_backwards(&root, bit, &target_entry);
+	if (ret < 0)
+		return print_bfs_bug(ret);
+	if (ret == 1)
+		return ret;
+
+	return print_irq_inversion_bug(curr, &root, target_entry,
+					this, 0, irqclass);
+}
+
+void print_irqtrace_events(struct task_struct *curr)
+{
+	printk("irq event stamp: %u\n", curr->irq_events);
+	printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
+	print_ip_sym(curr->hardirq_enable_ip);
+	printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
+	print_ip_sym(curr->hardirq_disable_ip);
+	printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
+	print_ip_sym(curr->softirq_enable_ip);
+	printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
+	print_ip_sym(curr->softirq_disable_ip);
+}
+
+static int HARDIRQ_verbose(struct lock_class *class)
+{
+#if HARDIRQ_VERBOSE
+	return class_filter(class);
+#endif
+	return 0;
+}
+
+static int SOFTIRQ_verbose(struct lock_class *class)
+{
+#if SOFTIRQ_VERBOSE
+	return class_filter(class);
+#endif
+	return 0;
+}
+
+static int RECLAIM_FS_verbose(struct lock_class *class)
+{
+#if RECLAIM_VERBOSE
+	return class_filter(class);
+#endif
+	return 0;
+}
+
+#define STRICT_READ_CHECKS	1
+
+static int (*state_verbose_f[])(struct lock_class *class) = {
+#define LOCKDEP_STATE(__STATE) \
+	__STATE##_verbose,
+#include "lockdep_states.h"
+#undef LOCKDEP_STATE
+};
+
+static inline int state_verbose(enum lock_usage_bit bit,
+				struct lock_class *class)
+{
+	return state_verbose_f[bit >> 2](class);
+}
+
+typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
+			     enum lock_usage_bit bit, const char *name);
+
+static int
+mark_lock_irq(struct task_struct *curr, struct held_lock *this,
+		enum lock_usage_bit new_bit)
+{
+	int excl_bit = exclusive_bit(new_bit);
+	int read = new_bit & 1;
+	int dir = new_bit & 2;
+
+	/*
+	 * mark USED_IN has to look forwards -- to ensure no dependency
+	 * has ENABLED state, which would allow recursion deadlocks.
+	 *
+	 * mark ENABLED has to look backwards -- to ensure no dependee
+	 * has USED_IN state, which, again, would allow  recursion deadlocks.
+	 */
+	check_usage_f usage = dir ?
+		check_usage_backwards : check_usage_forwards;
+
+	/*
+	 * Validate that this particular lock does not have conflicting
+	 * usage states.
+	 */
+	if (!valid_state(curr, this, new_bit, excl_bit))
+		return 0;
+
+	/*
+	 * Validate that the lock dependencies don't have conflicting usage
+	 * states.
+	 */
+	if ((!read || !dir || STRICT_READ_CHECKS) &&
+			!usage(curr, this, excl_bit, state_name(new_bit & ~1)))
+		return 0;
+
+	/*
+	 * Check for read in write conflicts
+	 */
+	if (!read) {
+		if (!valid_state(curr, this, new_bit, excl_bit + 1))
+			return 0;
+
+		if (STRICT_READ_CHECKS &&
+			!usage(curr, this, excl_bit + 1,
+				state_name(new_bit + 1)))
+			return 0;
+	}
+
+	if (state_verbose(new_bit, hlock_class(this)))
+		return 2;
+
+	return 1;
+}
+
+enum mark_type {
+#define LOCKDEP_STATE(__STATE)	__STATE,
+#include "lockdep_states.h"
+#undef LOCKDEP_STATE
+};
+
+/*
+ * Mark all held locks with a usage bit:
+ */
+static int
+mark_held_locks(struct task_struct *curr, enum mark_type mark)
+{
+	enum lock_usage_bit usage_bit;
+	struct held_lock *hlock;
+	int i;
+
+	for (i = 0; i < curr->lockdep_depth; i++) {
+		hlock = curr->held_locks + i;
+
+		usage_bit = 2 + (mark << 2); /* ENABLED */
+		if (hlock->read)
+			usage_bit += 1; /* READ */
+
+		BUG_ON(usage_bit >= LOCK_USAGE_STATES);
+
+		if (!hlock->check)
+			continue;
+
+		if (!mark_lock(curr, hlock, usage_bit))
+			return 0;
+	}
+
+	return 1;
+}
+
+/*
+ * Hardirqs will be enabled:
+ */
+static void __trace_hardirqs_on_caller(unsigned long ip)
+{
+	struct task_struct *curr = current;
+
+	/* we'll do an OFF -> ON transition: */
+	curr->hardirqs_enabled = 1;
+
+	/*
+	 * We are going to turn hardirqs on, so set the
+	 * usage bit for all held locks:
+	 */
+	if (!mark_held_locks(curr, HARDIRQ))
+		return;
+	/*
+	 * If we have softirqs enabled, then set the usage
+	 * bit for all held locks. (disabled hardirqs prevented
+	 * this bit from being set before)
+	 */
+	if (curr->softirqs_enabled)
+		if (!mark_held_locks(curr, SOFTIRQ))
+			return;
+
+	curr->hardirq_enable_ip = ip;
+	curr->hardirq_enable_event = ++curr->irq_events;
+	debug_atomic_inc(hardirqs_on_events);
+}
+
+__visible void trace_hardirqs_on_caller(unsigned long ip)
+{
+	time_hardirqs_on(CALLER_ADDR0, ip);
+
+	if (unlikely(!debug_locks || current->lockdep_recursion))
+		return;
+
+	if (unlikely(current->hardirqs_enabled)) {
+		/*
+		 * Neither irq nor preemption are disabled here
+		 * so this is racy by nature but losing one hit
+		 * in a stat is not a big deal.
+		 */
+		__debug_atomic_inc(redundant_hardirqs_on);
+		return;
+	}
+
+	/*
+	 * We're enabling irqs and according to our state above irqs weren't
+	 * already enabled, yet we find the hardware thinks they are in fact
+	 * enabled.. someone messed up their IRQ state tracing.
+	 */
+	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+		return;
+
+	/*
+	 * See the fine text that goes along with this variable definition.
+	 */
+	if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
+		return;
+
+	/*
+	 * Can't allow enabling interrupts while in an interrupt handler,
+	 * that's general bad form and such. Recursion, limited stack etc..
+	 */
+	if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
+		return;
+
+	current->lockdep_recursion = 1;
+	__trace_hardirqs_on_caller(ip);
+	current->lockdep_recursion = 0;
+}
+EXPORT_SYMBOL(trace_hardirqs_on_caller);
+
+void trace_hardirqs_on(void)
+{
+	trace_hardirqs_on_caller(CALLER_ADDR0);
+}
+EXPORT_SYMBOL(trace_hardirqs_on);
+
+/*
+ * Hardirqs were disabled:
+ */
+__visible void trace_hardirqs_off_caller(unsigned long ip)
+{
+	struct task_struct *curr = current;
+
+	time_hardirqs_off(CALLER_ADDR0, ip);
+
+	if (unlikely(!debug_locks || current->lockdep_recursion))
+		return;
+
+	/*
+	 * So we're supposed to get called after you mask local IRQs, but for
+	 * some reason the hardware doesn't quite think you did a proper job.
+	 */
+	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+		return;
+
+	if (curr->hardirqs_enabled) {
+		/*
+		 * We have done an ON -> OFF transition:
+		 */
+		curr->hardirqs_enabled = 0;
+		curr->hardirq_disable_ip = ip;
+		curr->hardirq_disable_event = ++curr->irq_events;
+		debug_atomic_inc(hardirqs_off_events);
+	} else
+		debug_atomic_inc(redundant_hardirqs_off);
+}
+EXPORT_SYMBOL(trace_hardirqs_off_caller);
+
+void trace_hardirqs_off(void)
+{
+	trace_hardirqs_off_caller(CALLER_ADDR0);
+}
+EXPORT_SYMBOL(trace_hardirqs_off);
+
+/*
+ * Softirqs will be enabled:
+ */
+void trace_softirqs_on(unsigned long ip)
+{
+	struct task_struct *curr = current;
+
+	if (unlikely(!debug_locks || current->lockdep_recursion))
+		return;
+
+	/*
+	 * We fancy IRQs being disabled here, see softirq.c, avoids
+	 * funny state and nesting things.
+	 */
+	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+		return;
+
+	if (curr->softirqs_enabled) {
+		debug_atomic_inc(redundant_softirqs_on);
+		return;
+	}
+
+	current->lockdep_recursion = 1;
+	/*
+	 * We'll do an OFF -> ON transition:
+	 */
+	curr->softirqs_enabled = 1;
+	curr->softirq_enable_ip = ip;
+	curr->softirq_enable_event = ++curr->irq_events;
+	debug_atomic_inc(softirqs_on_events);
+	/*
+	 * We are going to turn softirqs on, so set the
+	 * usage bit for all held locks, if hardirqs are
+	 * enabled too:
+	 */
+	if (curr->hardirqs_enabled)
+		mark_held_locks(curr, SOFTIRQ);
+	current->lockdep_recursion = 0;
+}
+
+/*
+ * Softirqs were disabled:
+ */
+void trace_softirqs_off(unsigned long ip)
+{
+	struct task_struct *curr = current;
+
+	if (unlikely(!debug_locks || current->lockdep_recursion))
+		return;
+
+	/*
+	 * We fancy IRQs being disabled here, see softirq.c
+	 */
+	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+		return;
+
+	if (curr->softirqs_enabled) {
+		/*
+		 * We have done an ON -> OFF transition:
+		 */
+		curr->softirqs_enabled = 0;
+		curr->softirq_disable_ip = ip;
+		curr->softirq_disable_event = ++curr->irq_events;
+		debug_atomic_inc(softirqs_off_events);
+		/*
+		 * Whoops, we wanted softirqs off, so why aren't they?
+		 */
+		DEBUG_LOCKS_WARN_ON(!softirq_count());
+	} else
+		debug_atomic_inc(redundant_softirqs_off);
+}
+
+static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
+{
+	struct task_struct *curr = current;
+
+	if (unlikely(!debug_locks))
+		return;
+
+	/* no reclaim without waiting on it */
+	if (!(gfp_mask & __GFP_WAIT))
+		return;
+
+	/* this guy won't enter reclaim */
+	if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
+		return;
+
+	/* We're only interested __GFP_FS allocations for now */
+	if (!(gfp_mask & __GFP_FS))
+		return;
+
+	/*
+	 * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
+	 */
+	if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
+		return;
+
+	mark_held_locks(curr, RECLAIM_FS);
+}
+
+static void check_flags(unsigned long flags);
+
+void lockdep_trace_alloc(gfp_t gfp_mask)
+{
+	unsigned long flags;
+
+	if (unlikely(current->lockdep_recursion))
+		return;
+
+	raw_local_irq_save(flags);
+	check_flags(flags);
+	current->lockdep_recursion = 1;
+	__lockdep_trace_alloc(gfp_mask, flags);
+	current->lockdep_recursion = 0;
+	raw_local_irq_restore(flags);
+}
+
+static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
+{
+	/*
+	 * If non-trylock use in a hardirq or softirq context, then
+	 * mark the lock as used in these contexts:
+	 */
+	if (!hlock->trylock) {
+		if (hlock->read) {
+			if (curr->hardirq_context)
+				if (!mark_lock(curr, hlock,
+						LOCK_USED_IN_HARDIRQ_READ))
+					return 0;
+			if (curr->softirq_context)
+				if (!mark_lock(curr, hlock,
+						LOCK_USED_IN_SOFTIRQ_READ))
+					return 0;
+		} else {
+			if (curr->hardirq_context)
+				if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
+					return 0;
+			if (curr->softirq_context)
+				if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
+					return 0;
+		}
+	}
+	if (!hlock->hardirqs_off) {
+		if (hlock->read) {
+			if (!mark_lock(curr, hlock,
+					LOCK_ENABLED_HARDIRQ_READ))
+				return 0;
+			if (curr->softirqs_enabled)
+				if (!mark_lock(curr, hlock,
+						LOCK_ENABLED_SOFTIRQ_READ))
+					return 0;
+		} else {
+			if (!mark_lock(curr, hlock,
+					LOCK_ENABLED_HARDIRQ))
+				return 0;
+			if (curr->softirqs_enabled)
+				if (!mark_lock(curr, hlock,
+						LOCK_ENABLED_SOFTIRQ))
+					return 0;
+		}
+	}
+
+	/*
+	 * We reuse the irq context infrastructure more broadly as a general
+	 * context checking code. This tests GFP_FS recursion (a lock taken
+	 * during reclaim for a GFP_FS allocation is held over a GFP_FS
+	 * allocation).
+	 */
+	if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
+		if (hlock->read) {
+			if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
+					return 0;
+		} else {
+			if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
+					return 0;
+		}
+	}
+
+	return 1;
+}
+
+static int separate_irq_context(struct task_struct *curr,
+		struct held_lock *hlock)
+{
+	unsigned int depth = curr->lockdep_depth;
+
+	/*
+	 * Keep track of points where we cross into an interrupt context:
+	 */
+	hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
+				curr->softirq_context;
+	if (depth) {
+		struct held_lock *prev_hlock;
+
+		prev_hlock = curr->held_locks + depth-1;
+		/*
+		 * If we cross into another context, reset the
+		 * hash key (this also prevents the checking and the
+		 * adding of the dependency to 'prev'):
+		 */
+		if (prev_hlock->irq_context != hlock->irq_context)
+			return 1;
+	}
+	return 0;
+}
+
+#else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
+
+static inline
+int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
+		enum lock_usage_bit new_bit)
+{
+	WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
+	return 1;
+}
+
+static inline int mark_irqflags(struct task_struct *curr,
+		struct held_lock *hlock)
+{
+	return 1;
+}
+
+static inline int separate_irq_context(struct task_struct *curr,
+		struct held_lock *hlock)
+{
+	return 0;
+}
+
+void lockdep_trace_alloc(gfp_t gfp_mask)
+{
+}
+
+#endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
+
+/*
+ * Mark a lock with a usage bit, and validate the state transition:
+ */
+static int mark_lock(struct task_struct *curr, struct held_lock *this,
+			     enum lock_usage_bit new_bit)
+{
+	unsigned int new_mask = 1 << new_bit, ret = 1;
+
+	/*
+	 * If already set then do not dirty the cacheline,
+	 * nor do any checks:
+	 */
+	if (likely(hlock_class(this)->usage_mask & new_mask))
+		return 1;
+
+	if (!graph_lock())
+		return 0;
+	/*
+	 * Make sure we didn't race:
+	 */
+	if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
+		graph_unlock();
+		return 1;
+	}
+
+	hlock_class(this)->usage_mask |= new_mask;
+
+	if (!save_trace(hlock_class(this)->usage_traces + new_bit))
+		return 0;
+
+	switch (new_bit) {
+#define LOCKDEP_STATE(__STATE)			\
+	case LOCK_USED_IN_##__STATE:		\
+	case LOCK_USED_IN_##__STATE##_READ:	\
+	case LOCK_ENABLED_##__STATE:		\
+	case LOCK_ENABLED_##__STATE##_READ:
+#include "lockdep_states.h"
+#undef LOCKDEP_STATE
+		ret = mark_lock_irq(curr, this, new_bit);
+		if (!ret)
+			return 0;
+		break;
+	case LOCK_USED:
+		debug_atomic_dec(nr_unused_locks);
+		break;
+	default:
+		if (!debug_locks_off_graph_unlock())
+			return 0;
+		WARN_ON(1);
+		return 0;
+	}
+
+	graph_unlock();
+
+	/*
+	 * We must printk outside of the graph_lock:
+	 */
+	if (ret == 2) {
+		printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
+		print_lock(this);
+		print_irqtrace_events(curr);
+		dump_stack();
+	}
+
+	return ret;
+}
+
+/*
+ * Initialize a lock instance's lock-class mapping info:
+ */
+void lockdep_init_map(struct lockdep_map *lock, const char *name,
+		      struct lock_class_key *key, int subclass)
+{
+	int i;
+
+	kmemcheck_mark_initialized(lock, sizeof(*lock));
+
+	for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
+		lock->class_cache[i] = NULL;
+
+#ifdef CONFIG_LOCK_STAT
+	lock->cpu = raw_smp_processor_id();
+#endif
+
+	/*
+	 * Can't be having no nameless bastards around this place!
+	 */
+	if (DEBUG_LOCKS_WARN_ON(!name)) {
+		lock->name = "NULL";
+		return;
+	}
+
+	lock->name = name;
+
+	/*
+	 * No key, no joy, we need to hash something.
+	 */
+	if (DEBUG_LOCKS_WARN_ON(!key))
+		return;
+	/*
+	 * Sanity check, the lock-class key must be persistent:
+	 */
+	if (!static_obj(key)) {
+		printk("BUG: key %p not in .data!\n", key);
+		/*
+		 * What it says above ^^^^^, I suggest you read it.
+		 */
+		DEBUG_LOCKS_WARN_ON(1);
+		return;
+	}
+	lock->key = key;
+
+	if (unlikely(!debug_locks))
+		return;
+
+	if (subclass) {
+		unsigned long flags;
+
+		if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion))
+			return;
+
+		raw_local_irq_save(flags);
+		current->lockdep_recursion = 1;
+		register_lock_class(lock, subclass, 1);
+		current->lockdep_recursion = 0;
+		raw_local_irq_restore(flags);
+	}
+}
+EXPORT_SYMBOL_GPL(lockdep_init_map);
+
+struct lock_class_key __lockdep_no_validate__;
+EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
+
+static int
+print_lock_nested_lock_not_held(struct task_struct *curr,
+				struct held_lock *hlock,
+				unsigned long ip)
+{
+	if (!debug_locks_off())
+		return 0;
+	if (debug_locks_silent)
+		return 0;
+
+	printk("\n");
+	printk("==================================\n");
+	printk("[ BUG: Nested lock was not taken ]\n");
+	print_kernel_ident();
+	printk("----------------------------------\n");
+
+	printk("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
+	print_lock(hlock);
+
+	printk("\nbut this task is not holding:\n");
+	printk("%s\n", hlock->nest_lock->name);
+
+	printk("\nstack backtrace:\n");
+	dump_stack();
+
+	printk("\nother info that might help us debug this:\n");
+	lockdep_print_held_locks(curr);
+
+	printk("\nstack backtrace:\n");
+	dump_stack();
+
+	return 0;
+}
+
+static int __lock_is_held(struct lockdep_map *lock);
+
+/*
+ * This gets called for every mutex_lock*()/spin_lock*() operation.
+ * We maintain the dependency maps and validate the locking attempt:
+ */
+static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
+			  int trylock, int read, int check, int hardirqs_off,
+			  struct lockdep_map *nest_lock, unsigned long ip,
+			  int references)
+{
+	struct task_struct *curr = current;
+	struct lock_class *class = NULL;
+	struct held_lock *hlock;
+	unsigned int depth, id;
+	int chain_head = 0;
+	int class_idx;
+	u64 chain_key;
+
+	if (unlikely(!debug_locks))
+		return 0;
+
+	/*
+	 * Lockdep should run with IRQs disabled, otherwise we could
+	 * get an interrupt which would want to take locks, which would
+	 * end up in lockdep and have you got a head-ache already?
+	 */
+	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+		return 0;
+
+	if (!prove_locking || lock->key == &__lockdep_no_validate__)
+		check = 0;
+
+	if (subclass < NR_LOCKDEP_CACHING_CLASSES)
+		class = lock->class_cache[subclass];
+	/*
+	 * Not cached?
+	 */
+	if (unlikely(!class)) {
+		class = register_lock_class(lock, subclass, 0);
+		if (!class)
+			return 0;
+	}
+	atomic_inc((atomic_t *)&class->ops);
+	if (very_verbose(class)) {
+		printk("\nacquire class [%p] %s", class->key, class->name);
+		if (class->name_version > 1)
+			printk("#%d", class->name_version);
+		printk("\n");
+		dump_stack();
+	}
+
+	/*
+	 * Add the lock to the list of currently held locks.
+	 * (we dont increase the depth just yet, up until the
+	 * dependency checks are done)
+	 */
+	depth = curr->lockdep_depth;
+	/*
+	 * Ran out of static storage for our per-task lock stack again have we?
+	 */
+	if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
+		return 0;
+
+	class_idx = class - lock_classes + 1;
+
+	if (depth) {
+		hlock = curr->held_locks + depth - 1;
+		if (hlock->class_idx == class_idx && nest_lock) {
+			if (hlock->references)
+				hlock->references++;
+			else
+				hlock->references = 2;
+
+			return 1;
+		}
+	}
+
+	hlock = curr->held_locks + depth;
+	/*
+	 * Plain impossible, we just registered it and checked it weren't no
+	 * NULL like.. I bet this mushroom I ate was good!
+	 */
+	if (DEBUG_LOCKS_WARN_ON(!class))
+		return 0;
+	hlock->class_idx = class_idx;
+	hlock->acquire_ip = ip;
+	hlock->instance = lock;
+	hlock->nest_lock = nest_lock;
+	hlock->trylock = trylock;
+	hlock->read = read;
+	hlock->check = check;
+	hlock->hardirqs_off = !!hardirqs_off;
+	hlock->references = references;
+#ifdef CONFIG_LOCK_STAT
+	hlock->waittime_stamp = 0;
+	hlock->holdtime_stamp = lockstat_clock();
+#endif
+
+	if (check && !mark_irqflags(curr, hlock))
+		return 0;
+
+	/* mark it as used: */
+	if (!mark_lock(curr, hlock, LOCK_USED))
+		return 0;
+
+	/*
+	 * Calculate the chain hash: it's the combined hash of all the
+	 * lock keys along the dependency chain. We save the hash value
+	 * at every step so that we can get the current hash easily
+	 * after unlock. The chain hash is then used to cache dependency
+	 * results.
+	 *
+	 * The 'key ID' is what is the most compact key value to drive
+	 * the hash, not class->key.
+	 */
+	id = class - lock_classes;
+	/*
+	 * Whoops, we did it again.. ran straight out of our static allocation.
+	 */
+	if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
+		return 0;
+
+	chain_key = curr->curr_chain_key;
+	if (!depth) {
+		/*
+		 * How can we have a chain hash when we ain't got no keys?!
+		 */
+		if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
+			return 0;
+		chain_head = 1;
+	}
+
+	hlock->prev_chain_key = chain_key;
+	if (separate_irq_context(curr, hlock)) {
+		chain_key = 0;
+		chain_head = 1;
+	}
+	chain_key = iterate_chain_key(chain_key, id);
+
+	if (nest_lock && !__lock_is_held(nest_lock))
+		return print_lock_nested_lock_not_held(curr, hlock, ip);
+
+	if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
+		return 0;
+
+	curr->curr_chain_key = chain_key;
+	curr->lockdep_depth++;
+	check_chain_key(curr);
+#ifdef CONFIG_DEBUG_LOCKDEP
+	if (unlikely(!debug_locks))
+		return 0;
+#endif
+	if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
+		debug_locks_off();
+		print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
+		printk(KERN_DEBUG "depth: %i  max: %lu!\n",
+		       curr->lockdep_depth, MAX_LOCK_DEPTH);
+
+		lockdep_print_held_locks(current);
+		debug_show_all_locks();
+		dump_stack();
+
+		return 0;
+	}
+
+	if (unlikely(curr->lockdep_depth > max_lockdep_depth))
+		max_lockdep_depth = curr->lockdep_depth;
+
+	return 1;
+}
+
+static int
+print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
+			   unsigned long ip)
+{
+	if (!debug_locks_off())
+		return 0;
+	if (debug_locks_silent)
+		return 0;
+
+	printk("\n");
+	printk("=====================================\n");
+	printk("[ BUG: bad unlock balance detected! ]\n");
+	print_kernel_ident();
+	printk("-------------------------------------\n");
+	printk("%s/%d is trying to release lock (",
+		curr->comm, task_pid_nr(curr));
+	print_lockdep_cache(lock);
+	printk(") at:\n");
+	print_ip_sym(ip);
+	printk("but there are no more locks to release!\n");
+	printk("\nother info that might help us debug this:\n");
+	lockdep_print_held_locks(curr);
+
+	printk("\nstack backtrace:\n");
+	dump_stack();
+
+	return 0;
+}
+
+/*
+ * Common debugging checks for both nested and non-nested unlock:
+ */
+static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
+			unsigned long ip)
+{
+	if (unlikely(!debug_locks))
+		return 0;
+	/*
+	 * Lockdep should run with IRQs disabled, recursion, head-ache, etc..
+	 */
+	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+		return 0;
+
+	if (curr->lockdep_depth <= 0)
+		return print_unlock_imbalance_bug(curr, lock, ip);
+
+	return 1;
+}
+
+static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
+{
+	if (hlock->instance == lock)
+		return 1;
+
+	if (hlock->references) {
+		struct lock_class *class = lock->class_cache[0];
+
+		if (!class)
+			class = look_up_lock_class(lock, 0);
+
+		/*
+		 * If look_up_lock_class() failed to find a class, we're trying
+		 * to test if we hold a lock that has never yet been acquired.
+		 * Clearly if the lock hasn't been acquired _ever_, we're not
+		 * holding it either, so report failure.
+		 */
+		if (!class)
+			return 0;
+
+		/*
+		 * References, but not a lock we're actually ref-counting?
+		 * State got messed up, follow the sites that change ->references
+		 * and try to make sense of it.
+		 */
+		if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
+			return 0;
+
+		if (hlock->class_idx == class - lock_classes + 1)
+			return 1;
+	}
+
+	return 0;
+}
+
+static int
+__lock_set_class(struct lockdep_map *lock, const char *name,
+		 struct lock_class_key *key, unsigned int subclass,
+		 unsigned long ip)
+{
+	struct task_struct *curr = current;
+	struct held_lock *hlock, *prev_hlock;
+	struct lock_class *class;
+	unsigned int depth;
+	int i;
+
+	depth = curr->lockdep_depth;
+	/*
+	 * This function is about (re)setting the class of a held lock,
+	 * yet we're not actually holding any locks. Naughty user!
+	 */
+	if (DEBUG_LOCKS_WARN_ON(!depth))
+		return 0;
+
+	prev_hlock = NULL;
+	for (i = depth-1; i >= 0; i--) {
+		hlock = curr->held_locks + i;
+		/*
+		 * We must not cross into another context:
+		 */
+		if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
+			break;
+		if (match_held_lock(hlock, lock))
+			goto found_it;
+		prev_hlock = hlock;
+	}
+	return print_unlock_imbalance_bug(curr, lock, ip);
+
+found_it:
+	lockdep_init_map(lock, name, key, 0);
+	class = register_lock_class(lock, subclass, 0);
+	hlock->class_idx = class - lock_classes + 1;
+
+	curr->lockdep_depth = i;
+	curr->curr_chain_key = hlock->prev_chain_key;
+
+	for (; i < depth; i++) {
+		hlock = curr->held_locks + i;
+		if (!__lock_acquire(hlock->instance,
+			hlock_class(hlock)->subclass, hlock->trylock,
+				hlock->read, hlock->check, hlock->hardirqs_off,
+				hlock->nest_lock, hlock->acquire_ip,
+				hlock->references))
+			return 0;
+	}
+
+	/*
+	 * I took it apart and put it back together again, except now I have
+	 * these 'spare' parts.. where shall I put them.
+	 */
+	if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
+		return 0;
+	return 1;
+}
+
+/*
+ * Remove the lock to the list of currently held locks in a
+ * potentially non-nested (out of order) manner. This is a
+ * relatively rare operation, as all the unlock APIs default
+ * to nested mode (which uses lock_release()):
+ */
+static int
+lock_release_non_nested(struct task_struct *curr,
+			struct lockdep_map *lock, unsigned long ip)
+{
+	struct held_lock *hlock, *prev_hlock;
+	unsigned int depth;
+	int i;
+
+	/*
+	 * Check whether the lock exists in the current stack
+	 * of held locks:
+	 */
+	depth = curr->lockdep_depth;
+	/*
+	 * So we're all set to release this lock.. wait what lock? We don't
+	 * own any locks, you've been drinking again?
+	 */
+	if (DEBUG_LOCKS_WARN_ON(!depth))
+		return 0;
+
+	prev_hlock = NULL;
+	for (i = depth-1; i >= 0; i--) {
+		hlock = curr->held_locks + i;
+		/*
+		 * We must not cross into another context:
+		 */
+		if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
+			break;
+		if (match_held_lock(hlock, lock))
+			goto found_it;
+		prev_hlock = hlock;
+	}
+	return print_unlock_imbalance_bug(curr, lock, ip);
+
+found_it:
+	if (hlock->instance == lock)
+		lock_release_holdtime(hlock);
+
+	if (hlock->references) {
+		hlock->references--;
+		if (hlock->references) {
+			/*
+			 * We had, and after removing one, still have
+			 * references, the current lock stack is still
+			 * valid. We're done!
+			 */
+			return 1;
+		}
+	}
+
+	/*
+	 * We have the right lock to unlock, 'hlock' points to it.
+	 * Now we remove it from the stack, and add back the other
+	 * entries (if any), recalculating the hash along the way:
+	 */
+
+	curr->lockdep_depth = i;
+	curr->curr_chain_key = hlock->prev_chain_key;
+
+	for (i++; i < depth; i++) {
+		hlock = curr->held_locks + i;
+		if (!__lock_acquire(hlock->instance,
+			hlock_class(hlock)->subclass, hlock->trylock,
+				hlock->read, hlock->check, hlock->hardirqs_off,
+				hlock->nest_lock, hlock->acquire_ip,
+				hlock->references))
+			return 0;
+	}
+
+	/*
+	 * We had N bottles of beer on the wall, we drank one, but now
+	 * there's not N-1 bottles of beer left on the wall...
+	 */
+	if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
+		return 0;
+	return 1;
+}
+
+/*
+ * Remove the lock to the list of currently held locks - this gets
+ * called on mutex_unlock()/spin_unlock*() (or on a failed
+ * mutex_lock_interruptible()). This is done for unlocks that nest
+ * perfectly. (i.e. the current top of the lock-stack is unlocked)
+ */
+static int lock_release_nested(struct task_struct *curr,
+			       struct lockdep_map *lock, unsigned long ip)
+{
+	struct held_lock *hlock;
+	unsigned int depth;
+
+	/*
+	 * Pop off the top of the lock stack:
+	 */
+	depth = curr->lockdep_depth - 1;
+	hlock = curr->held_locks + depth;
+
+	/*
+	 * Is the unlock non-nested:
+	 */
+	if (hlock->instance != lock || hlock->references)
+		return lock_release_non_nested(curr, lock, ip);
+	curr->lockdep_depth--;
+
+	/*
+	 * No more locks, but somehow we've got hash left over, who left it?
+	 */
+	if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
+		return 0;
+
+	curr->curr_chain_key = hlock->prev_chain_key;
+
+	lock_release_holdtime(hlock);
+
+#ifdef CONFIG_DEBUG_LOCKDEP
+	hlock->prev_chain_key = 0;
+	hlock->class_idx = 0;
+	hlock->acquire_ip = 0;
+	hlock->irq_context = 0;
+#endif
+	return 1;
+}
+
+/*
+ * Remove the lock to the list of currently held locks - this gets
+ * called on mutex_unlock()/spin_unlock*() (or on a failed
+ * mutex_lock_interruptible()). This is done for unlocks that nest
+ * perfectly. (i.e. the current top of the lock-stack is unlocked)
+ */
+static void
+__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
+{
+	struct task_struct *curr = current;
+
+	if (!check_unlock(curr, lock, ip))
+		return;
+
+	if (nested) {
+		if (!lock_release_nested(curr, lock, ip))
+			return;
+	} else {
+		if (!lock_release_non_nested(curr, lock, ip))
+			return;
+	}
+
+	check_chain_key(curr);
+}
+
+static int __lock_is_held(struct lockdep_map *lock)
+{
+	struct task_struct *curr = current;
+	int i;
+
+	for (i = 0; i < curr->lockdep_depth; i++) {
+		struct held_lock *hlock = curr->held_locks + i;
+
+		if (match_held_lock(hlock, lock))
+			return 1;
+	}
+
+	return 0;
+}
+
+/*
+ * Check whether we follow the irq-flags state precisely:
+ */
+static void check_flags(unsigned long flags)
+{
+#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
+    defined(CONFIG_TRACE_IRQFLAGS)
+	if (!debug_locks)
+		return;
+
+	if (irqs_disabled_flags(flags)) {
+		if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
+			printk("possible reason: unannotated irqs-off.\n");
+		}
+	} else {
+		if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
+			printk("possible reason: unannotated irqs-on.\n");
+		}
+	}
+
+	/*
+	 * We dont accurately track softirq state in e.g.
+	 * hardirq contexts (such as on 4KSTACKS), so only
+	 * check if not in hardirq contexts:
+	 */
+	if (!hardirq_count()) {
+		if (softirq_count()) {
+			/* like the above, but with softirqs */
+			DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
+		} else {
+			/* lick the above, does it taste good? */
+			DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
+		}
+	}
+
+	if (!debug_locks)
+		print_irqtrace_events(current);
+#endif
+}
+
+void lock_set_class(struct lockdep_map *lock, const char *name,
+		    struct lock_class_key *key, unsigned int subclass,
+		    unsigned long ip)
+{
+	unsigned long flags;
+
+	if (unlikely(current->lockdep_recursion))
+		return;
+
+	raw_local_irq_save(flags);
+	current->lockdep_recursion = 1;
+	check_flags(flags);
+	if (__lock_set_class(lock, name, key, subclass, ip))
+		check_chain_key(current);
+	current->lockdep_recursion = 0;
+	raw_local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(lock_set_class);
+
+/*
+ * We are not always called with irqs disabled - do that here,
+ * and also avoid lockdep recursion:
+ */
+void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
+			  int trylock, int read, int check,
+			  struct lockdep_map *nest_lock, unsigned long ip)
+{
+	unsigned long flags;
+
+	if (unlikely(current->lockdep_recursion))
+		return;
+
+	raw_local_irq_save(flags);
+	check_flags(flags);
+
+	current->lockdep_recursion = 1;
+	trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
+	__lock_acquire(lock, subclass, trylock, read, check,
+		       irqs_disabled_flags(flags), nest_lock, ip, 0);
+	current->lockdep_recursion = 0;
+	raw_local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(lock_acquire);
+
+void lock_release(struct lockdep_map *lock, int nested,
+			  unsigned long ip)
+{
+	unsigned long flags;
+
+	if (unlikely(current->lockdep_recursion))
+		return;
+
+	raw_local_irq_save(flags);
+	check_flags(flags);
+	current->lockdep_recursion = 1;
+	trace_lock_release(lock, ip);
+	__lock_release(lock, nested, ip);
+	current->lockdep_recursion = 0;
+	raw_local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(lock_release);
+
+int lock_is_held(struct lockdep_map *lock)
+{
+	unsigned long flags;
+	int ret = 0;
+
+	if (unlikely(current->lockdep_recursion))
+		return 1; /* avoid false negative lockdep_assert_held() */
+
+	raw_local_irq_save(flags);
+	check_flags(flags);
+
+	current->lockdep_recursion = 1;
+	ret = __lock_is_held(lock);
+	current->lockdep_recursion = 0;
+	raw_local_irq_restore(flags);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(lock_is_held);
+
+void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
+{
+	current->lockdep_reclaim_gfp = gfp_mask;
+}
+
+void lockdep_clear_current_reclaim_state(void)
+{
+	current->lockdep_reclaim_gfp = 0;
+}
+
+#ifdef CONFIG_LOCK_STAT
+static int
+print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
+			   unsigned long ip)
+{
+	if (!debug_locks_off())
+		return 0;
+	if (debug_locks_silent)
+		return 0;
+
+	printk("\n");
+	printk("=================================\n");
+	printk("[ BUG: bad contention detected! ]\n");
+	print_kernel_ident();
+	printk("---------------------------------\n");
+	printk("%s/%d is trying to contend lock (",
+		curr->comm, task_pid_nr(curr));
+	print_lockdep_cache(lock);
+	printk(") at:\n");
+	print_ip_sym(ip);
+	printk("but there are no locks held!\n");
+	printk("\nother info that might help us debug this:\n");
+	lockdep_print_held_locks(curr);
+
+	printk("\nstack backtrace:\n");
+	dump_stack();
+
+	return 0;
+}
+
+static void
+__lock_contended(struct lockdep_map *lock, unsigned long ip)
+{
+	struct task_struct *curr = current;
+	struct held_lock *hlock, *prev_hlock;
+	struct lock_class_stats *stats;
+	unsigned int depth;
+	int i, contention_point, contending_point;
+
+	depth = curr->lockdep_depth;
+	/*
+	 * Whee, we contended on this lock, except it seems we're not
+	 * actually trying to acquire anything much at all..
+	 */
+	if (DEBUG_LOCKS_WARN_ON(!depth))
+		return;
+
+	prev_hlock = NULL;
+	for (i = depth-1; i >= 0; i--) {
+		hlock = curr->held_locks + i;
+		/*
+		 * We must not cross into another context:
+		 */
+		if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
+			break;
+		if (match_held_lock(hlock, lock))
+			goto found_it;
+		prev_hlock = hlock;
+	}
+	print_lock_contention_bug(curr, lock, ip);
+	return;
+
+found_it:
+	if (hlock->instance != lock)
+		return;
+
+	hlock->waittime_stamp = lockstat_clock();
+
+	contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
+	contending_point = lock_point(hlock_class(hlock)->contending_point,
+				      lock->ip);
+
+	stats = get_lock_stats(hlock_class(hlock));
+	if (contention_point < LOCKSTAT_POINTS)
+		stats->contention_point[contention_point]++;
+	if (contending_point < LOCKSTAT_POINTS)
+		stats->contending_point[contending_point]++;
+	if (lock->cpu != smp_processor_id())
+		stats->bounces[bounce_contended + !!hlock->read]++;
+	put_lock_stats(stats);
+}
+
+static void
+__lock_acquired(struct lockdep_map *lock, unsigned long ip)
+{
+	struct task_struct *curr = current;
+	struct held_lock *hlock, *prev_hlock;
+	struct lock_class_stats *stats;
+	unsigned int depth;
+	u64 now, waittime = 0;
+	int i, cpu;
+
+	depth = curr->lockdep_depth;
+	/*
+	 * Yay, we acquired ownership of this lock we didn't try to
+	 * acquire, how the heck did that happen?
+	 */
+	if (DEBUG_LOCKS_WARN_ON(!depth))
+		return;
+
+	prev_hlock = NULL;
+	for (i = depth-1; i >= 0; i--) {
+		hlock = curr->held_locks + i;
+		/*
+		 * We must not cross into another context:
+		 */
+		if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
+			break;
+		if (match_held_lock(hlock, lock))
+			goto found_it;
+		prev_hlock = hlock;
+	}
+	print_lock_contention_bug(curr, lock, _RET_IP_);
+	return;
+
+found_it:
+	if (hlock->instance != lock)
+		return;
+
+	cpu = smp_processor_id();
+	if (hlock->waittime_stamp) {
+		now = lockstat_clock();
+		waittime = now - hlock->waittime_stamp;
+		hlock->holdtime_stamp = now;
+	}
+
+	trace_lock_acquired(lock, ip);
+
+	stats = get_lock_stats(hlock_class(hlock));
+	if (waittime) {
+		if (hlock->read)
+			lock_time_inc(&stats->read_waittime, waittime);
+		else
+			lock_time_inc(&stats->write_waittime, waittime);
+	}
+	if (lock->cpu != cpu)
+		stats->bounces[bounce_acquired + !!hlock->read]++;
+	put_lock_stats(stats);
+
+	lock->cpu = cpu;
+	lock->ip = ip;
+}
+
+void lock_contended(struct lockdep_map *lock, unsigned long ip)
+{
+	unsigned long flags;
+
+	if (unlikely(!lock_stat))
+		return;
+
+	if (unlikely(current->lockdep_recursion))
+		return;
+
+	raw_local_irq_save(flags);
+	check_flags(flags);
+	current->lockdep_recursion = 1;
+	trace_lock_contended(lock, ip);
+	__lock_contended(lock, ip);
+	current->lockdep_recursion = 0;
+	raw_local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(lock_contended);
+
+void lock_acquired(struct lockdep_map *lock, unsigned long ip)
+{
+	unsigned long flags;
+
+	if (unlikely(!lock_stat))
+		return;
+
+	if (unlikely(current->lockdep_recursion))
+		return;
+
+	raw_local_irq_save(flags);
+	check_flags(flags);
+	current->lockdep_recursion = 1;
+	__lock_acquired(lock, ip);
+	current->lockdep_recursion = 0;
+	raw_local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(lock_acquired);
+#endif
+
+/*
+ * Used by the testsuite, sanitize the validator state
+ * after a simulated failure:
+ */
+
+void lockdep_reset(void)
+{
+	unsigned long flags;
+	int i;
+
+	raw_local_irq_save(flags);
+	current->curr_chain_key = 0;
+	current->lockdep_depth = 0;
+	current->lockdep_recursion = 0;
+	memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
+	nr_hardirq_chains = 0;
+	nr_softirq_chains = 0;
+	nr_process_chains = 0;
+	debug_locks = 1;
+	for (i = 0; i < CHAINHASH_SIZE; i++)
+		INIT_LIST_HEAD(chainhash_table + i);
+	raw_local_irq_restore(flags);
+}
+
+static void zap_class(struct lock_class *class)
+{
+	int i;
+
+	/*
+	 * Remove all dependencies this lock is
+	 * involved in:
+	 */
+	for (i = 0; i < nr_list_entries; i++) {
+		if (list_entries[i].class == class)
+			list_del_rcu(&list_entries[i].entry);
+	}
+	/*
+	 * Unhash the class and remove it from the all_lock_classes list:
+	 */
+	list_del_rcu(&class->hash_entry);
+	list_del_rcu(&class->lock_entry);
+
+	RCU_INIT_POINTER(class->key, NULL);
+	RCU_INIT_POINTER(class->name, NULL);
+}
+
+static inline int within(const void *addr, void *start, unsigned long size)
+{
+	return addr >= start && addr < start + size;
+}
+
+/*
+ * Used in module.c to remove lock classes from memory that is going to be
+ * freed; and possibly re-used by other modules.
+ *
+ * We will have had one sync_sched() before getting here, so we're guaranteed
+ * nobody will look up these exact classes -- they're properly dead but still
+ * allocated.
+ */
+void lockdep_free_key_range(void *start, unsigned long size)
+{
+	struct lock_class *class;
+	struct list_head *head;
+	unsigned long flags;
+	int i;
+	int locked;
+
+	raw_local_irq_save(flags);
+	locked = graph_lock();
+
+	/*
+	 * Unhash all classes that were created by this module:
+	 */
+	for (i = 0; i < CLASSHASH_SIZE; i++) {
+		head = classhash_table + i;
+		if (list_empty(head))
+			continue;
+		list_for_each_entry_rcu(class, head, hash_entry) {
+			if (within(class->key, start, size))
+				zap_class(class);
+			else if (within(class->name, start, size))
+				zap_class(class);
+		}
+	}
+
+	if (locked)
+		graph_unlock();
+	raw_local_irq_restore(flags);
+
+	/*
+	 * Wait for any possible iterators from look_up_lock_class() to pass
+	 * before continuing to free the memory they refer to.
+	 *
+	 * sync_sched() is sufficient because the read-side is IRQ disable.
+	 */
+	synchronize_sched();
+
+	/*
+	 * XXX at this point we could return the resources to the pool;
+	 * instead we leak them. We would need to change to bitmap allocators
+	 * instead of the linear allocators we have now.
+	 */
+}
+
+void lockdep_reset_lock(struct lockdep_map *lock)
+{
+	struct lock_class *class;
+	struct list_head *head;
+	unsigned long flags;
+	int i, j;
+	int locked;
+
+	raw_local_irq_save(flags);
+
+	/*
+	 * Remove all classes this lock might have:
+	 */
+	for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
+		/*
+		 * If the class exists we look it up and zap it:
+		 */
+		class = look_up_lock_class(lock, j);
+		if (class)
+			zap_class(class);
+	}
+	/*
+	 * Debug check: in the end all mapped classes should
+	 * be gone.
+	 */
+	locked = graph_lock();
+	for (i = 0; i < CLASSHASH_SIZE; i++) {
+		head = classhash_table + i;
+		if (list_empty(head))
+			continue;
+		list_for_each_entry_rcu(class, head, hash_entry) {
+			int match = 0;
+
+			for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
+				match |= class == lock->class_cache[j];
+
+			if (unlikely(match)) {
+				if (debug_locks_off_graph_unlock()) {
+					/*
+					 * We all just reset everything, how did it match?
+					 */
+					WARN_ON(1);
+				}
+				goto out_restore;
+			}
+		}
+	}
+	if (locked)
+		graph_unlock();
+
+out_restore:
+	raw_local_irq_restore(flags);
+}
+
+void lockdep_init(void)
+{
+	int i;
+
+	/*
+	 * Some architectures have their own start_kernel()
+	 * code which calls lockdep_init(), while we also
+	 * call lockdep_init() from the start_kernel() itself,
+	 * and we want to initialize the hashes only once:
+	 */
+	if (lockdep_initialized)
+		return;
+
+	for (i = 0; i < CLASSHASH_SIZE; i++)
+		INIT_LIST_HEAD(classhash_table + i);
+
+	for (i = 0; i < CHAINHASH_SIZE; i++)
+		INIT_LIST_HEAD(chainhash_table + i);
+
+	lockdep_initialized = 1;
+}
+
+void __init lockdep_info(void)
+{
+	printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
+
+	printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
+	printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
+	printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
+	printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
+	printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
+	printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
+	printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
+
+	printk(" memory used by lock dependency info: %lu kB\n",
+		(sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
+		sizeof(struct list_head) * CLASSHASH_SIZE +
+		sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
+		sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
+		sizeof(struct list_head) * CHAINHASH_SIZE
+#ifdef CONFIG_PROVE_LOCKING
+		+ sizeof(struct circular_queue)
+#endif
+		) / 1024
+		);
+
+	printk(" per task-struct memory footprint: %lu bytes\n",
+		sizeof(struct held_lock) * MAX_LOCK_DEPTH);
+
+#ifdef CONFIG_DEBUG_LOCKDEP
+	if (lockdep_init_error) {
+		printk("WARNING: lockdep init error! lock-%s was acquired"
+			"before lockdep_init\n", lock_init_error);
+		printk("Call stack leading to lockdep invocation was:\n");
+		print_stack_trace(&lockdep_init_trace, 0);
+	}
+#endif
+}
+
+static void
+print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
+		     const void *mem_to, struct held_lock *hlock)
+{
+	if (!debug_locks_off())
+		return;
+	if (debug_locks_silent)
+		return;
+
+	printk("\n");
+	printk("=========================\n");
+	printk("[ BUG: held lock freed! ]\n");
+	print_kernel_ident();
+	printk("-------------------------\n");
+	printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
+		curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
+	print_lock(hlock);
+	lockdep_print_held_locks(curr);
+
+	printk("\nstack backtrace:\n");
+	dump_stack();
+}
+
+static inline int not_in_range(const void* mem_from, unsigned long mem_len,
+				const void* lock_from, unsigned long lock_len)
+{
+	return lock_from + lock_len <= mem_from ||
+		mem_from + mem_len <= lock_from;
+}
+
+/*
+ * Called when kernel memory is freed (or unmapped), or if a lock
+ * is destroyed or reinitialized - this code checks whether there is
+ * any held lock in the memory range of <from> to <to>:
+ */
+void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
+{
+	struct task_struct *curr = current;
+	struct held_lock *hlock;
+	unsigned long flags;
+	int i;
+
+	if (unlikely(!debug_locks))
+		return;
+
+	local_irq_save(flags);
+	for (i = 0; i < curr->lockdep_depth; i++) {
+		hlock = curr->held_locks + i;
+
+		if (not_in_range(mem_from, mem_len, hlock->instance,
+					sizeof(*hlock->instance)))
+			continue;
+
+		print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
+		break;
+	}
+	local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
+
+static void print_held_locks_bug(void)
+{
+	if (!debug_locks_off())
+		return;
+	if (debug_locks_silent)
+		return;
+
+	printk("\n");
+	printk("=====================================\n");
+	printk("[ BUG: %s/%d still has locks held! ]\n",
+	       current->comm, task_pid_nr(current));
+	print_kernel_ident();
+	printk("-------------------------------------\n");
+	lockdep_print_held_locks(current);
+	printk("\nstack backtrace:\n");
+	dump_stack();
+}
+
+void debug_check_no_locks_held(void)
+{
+	if (unlikely(current->lockdep_depth > 0))
+		print_held_locks_bug();
+}
+EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
+
+#ifdef __KERNEL__
+void debug_show_all_locks(void)
+{
+	struct task_struct *g, *p;
+	int count = 10;
+	int unlock = 1;
+
+	if (unlikely(!debug_locks)) {
+		printk("INFO: lockdep is turned off.\n");
+		return;
+	}
+	printk("\nShowing all locks held in the system:\n");
+
+	/*
+	 * Here we try to get the tasklist_lock as hard as possible,
+	 * if not successful after 2 seconds we ignore it (but keep
+	 * trying). This is to enable a debug printout even if a
+	 * tasklist_lock-holding task deadlocks or crashes.
+	 */
+retry:
+	if (!read_trylock(&tasklist_lock)) {
+		if (count == 10)
+			printk("hm, tasklist_lock locked, retrying... ");
+		if (count) {
+			count--;
+			printk(" #%d", 10-count);
+			mdelay(200);
+			goto retry;
+		}
+		printk(" ignoring it.\n");
+		unlock = 0;
+	} else {
+		if (count != 10)
+			printk(KERN_CONT " locked it.\n");
+	}
+
+	do_each_thread(g, p) {
+		/*
+		 * It's not reliable to print a task's held locks
+		 * if it's not sleeping (or if it's not the current
+		 * task):
+		 */
+		if (p->state == TASK_RUNNING && p != current)
+			continue;
+		if (p->lockdep_depth)
+			lockdep_print_held_locks(p);
+		if (!unlock)
+			if (read_trylock(&tasklist_lock))
+				unlock = 1;
+	} while_each_thread(g, p);
+
+	printk("\n");
+	printk("=============================================\n\n");
+
+	if (unlock)
+		read_unlock(&tasklist_lock);
+}
+EXPORT_SYMBOL_GPL(debug_show_all_locks);
+#endif
+
+/*
+ * Careful: only use this function if you are sure that
+ * the task cannot run in parallel!
+ */
+void debug_show_held_locks(struct task_struct *task)
+{
+	if (unlikely(!debug_locks)) {
+		printk("INFO: lockdep is turned off.\n");
+		return;
+	}
+	lockdep_print_held_locks(task);
+}
+EXPORT_SYMBOL_GPL(debug_show_held_locks);
+
+asmlinkage __visible void lockdep_sys_exit(void)
+{
+	struct task_struct *curr = current;
+
+	if (unlikely(curr->lockdep_depth)) {
+		if (!debug_locks_off())
+			return;
+		printk("\n");
+		printk("================================================\n");
+		printk("[ BUG: lock held when returning to user space! ]\n");
+		print_kernel_ident();
+		printk("------------------------------------------------\n");
+		printk("%s/%d is leaving the kernel with locks still held!\n",
+				curr->comm, curr->pid);
+		lockdep_print_held_locks(curr);
+	}
+}
+
+void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
+{
+	struct task_struct *curr = current;
+
+#ifndef CONFIG_PROVE_RCU_REPEATEDLY
+	if (!debug_locks_off())
+		return;
+#endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
+	/* Note: the following can be executed concurrently, so be careful. */
+	printk("\n");
+	printk("===============================\n");
+	printk("[ INFO: suspicious RCU usage. ]\n");
+	print_kernel_ident();
+	printk("-------------------------------\n");
+	printk("%s:%d %s!\n", file, line, s);
+	printk("\nother info that might help us debug this:\n\n");
+	printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
+	       !rcu_lockdep_current_cpu_online()
+			? "RCU used illegally from offline CPU!\n"
+			: !rcu_is_watching()
+				? "RCU used illegally from idle CPU!\n"
+				: "",
+	       rcu_scheduler_active, debug_locks);
+
+	/*
+	 * If a CPU is in the RCU-free window in idle (ie: in the section
+	 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
+	 * considers that CPU to be in an "extended quiescent state",
+	 * which means that RCU will be completely ignoring that CPU.
+	 * Therefore, rcu_read_lock() and friends have absolutely no
+	 * effect on a CPU running in that state. In other words, even if
+	 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
+	 * delete data structures out from under it.  RCU really has no
+	 * choice here: we need to keep an RCU-free window in idle where
+	 * the CPU may possibly enter into low power mode. This way we can
+	 * notice an extended quiescent state to other CPUs that started a grace
+	 * period. Otherwise we would delay any grace period as long as we run
+	 * in the idle task.
+	 *
+	 * So complain bitterly if someone does call rcu_read_lock(),
+	 * rcu_read_lock_bh() and so on from extended quiescent states.
+	 */
+	if (!rcu_is_watching())
+		printk("RCU used illegally from extended quiescent state!\n");
+
+	lockdep_print_held_locks(curr);
+	printk("\nstack backtrace:\n");
+	dump_stack();
+}
+EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);
diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h
new file mode 100644
index 000000000..51c4b24b6
--- /dev/null
+++ b/kernel/locking/lockdep_internals.h
@@ -0,0 +1,170 @@
+/*
+ * kernel/lockdep_internals.h
+ *
+ * Runtime locking correctness validator
+ *
+ * lockdep subsystem internal functions and variables.
+ */
+
+/*
+ * Lock-class usage-state bits:
+ */
+enum lock_usage_bit {
+#define LOCKDEP_STATE(__STATE)		\
+	LOCK_USED_IN_##__STATE,		\
+	LOCK_USED_IN_##__STATE##_READ,	\
+	LOCK_ENABLED_##__STATE,		\
+	LOCK_ENABLED_##__STATE##_READ,
+#include "lockdep_states.h"
+#undef LOCKDEP_STATE
+	LOCK_USED,
+	LOCK_USAGE_STATES
+};
+
+/*
+ * Usage-state bitmasks:
+ */
+#define __LOCKF(__STATE)	LOCKF_##__STATE = (1 << LOCK_##__STATE),
+
+enum {
+#define LOCKDEP_STATE(__STATE)						\
+	__LOCKF(USED_IN_##__STATE)					\
+	__LOCKF(USED_IN_##__STATE##_READ)				\
+	__LOCKF(ENABLED_##__STATE)					\
+	__LOCKF(ENABLED_##__STATE##_READ)
+#include "lockdep_states.h"
+#undef LOCKDEP_STATE
+	__LOCKF(USED)
+};
+
+#define LOCKF_ENABLED_IRQ (LOCKF_ENABLED_HARDIRQ | LOCKF_ENABLED_SOFTIRQ)
+#define LOCKF_USED_IN_IRQ (LOCKF_USED_IN_HARDIRQ | LOCKF_USED_IN_SOFTIRQ)
+
+#define LOCKF_ENABLED_IRQ_READ \
+		(LOCKF_ENABLED_HARDIRQ_READ | LOCKF_ENABLED_SOFTIRQ_READ)
+#define LOCKF_USED_IN_IRQ_READ \
+		(LOCKF_USED_IN_HARDIRQ_READ | LOCKF_USED_IN_SOFTIRQ_READ)
+
+/*
+ * MAX_LOCKDEP_ENTRIES is the maximum number of lock dependencies
+ * we track.
+ *
+ * We use the per-lock dependency maps in two ways: we grow it by adding
+ * every to-be-taken lock to all currently held lock's own dependency
+ * table (if it's not there yet), and we check it for lock order
+ * conflicts and deadlocks.
+ */
+#define MAX_LOCKDEP_ENTRIES	32768UL
+
+#define MAX_LOCKDEP_CHAINS_BITS	16
+#define MAX_LOCKDEP_CHAINS	(1UL << MAX_LOCKDEP_CHAINS_BITS)
+
+#define MAX_LOCKDEP_CHAIN_HLOCKS (MAX_LOCKDEP_CHAINS*5)
+
+/*
+ * Stack-trace: tightly packed array of stack backtrace
+ * addresses. Protected by the hash_lock.
+ */
+#define MAX_STACK_TRACE_ENTRIES	524288UL
+
+extern struct list_head all_lock_classes;
+extern struct lock_chain lock_chains[];
+
+#define LOCK_USAGE_CHARS (1+LOCK_USAGE_STATES/2)
+
+extern void get_usage_chars(struct lock_class *class,
+			    char usage[LOCK_USAGE_CHARS]);
+
+extern const char * __get_key_name(struct lockdep_subclass_key *key, char *str);
+
+struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i);
+
+extern unsigned long nr_lock_classes;
+extern unsigned long nr_list_entries;
+extern unsigned long nr_lock_chains;
+extern int nr_chain_hlocks;
+extern unsigned long nr_stack_trace_entries;
+
+extern unsigned int nr_hardirq_chains;
+extern unsigned int nr_softirq_chains;
+extern unsigned int nr_process_chains;
+extern unsigned int max_lockdep_depth;
+extern unsigned int max_recursion_depth;
+
+extern unsigned int max_bfs_queue_depth;
+
+#ifdef CONFIG_PROVE_LOCKING
+extern unsigned long lockdep_count_forward_deps(struct lock_class *);
+extern unsigned long lockdep_count_backward_deps(struct lock_class *);
+#else
+static inline unsigned long
+lockdep_count_forward_deps(struct lock_class *class)
+{
+	return 0;
+}
+static inline unsigned long
+lockdep_count_backward_deps(struct lock_class *class)
+{
+	return 0;
+}
+#endif
+
+#ifdef CONFIG_DEBUG_LOCKDEP
+
+#include <asm/local.h>
+/*
+ * Various lockdep statistics.
+ * We want them per cpu as they are often accessed in fast path
+ * and we want to avoid too much cache bouncing.
+ */
+struct lockdep_stats {
+	int	chain_lookup_hits;
+	int	chain_lookup_misses;
+	int	hardirqs_on_events;
+	int	hardirqs_off_events;
+	int	redundant_hardirqs_on;
+	int	redundant_hardirqs_off;
+	int	softirqs_on_events;
+	int	softirqs_off_events;
+	int	redundant_softirqs_on;
+	int	redundant_softirqs_off;
+	int	nr_unused_locks;
+	int	nr_cyclic_checks;
+	int	nr_cyclic_check_recursions;
+	int	nr_find_usage_forwards_checks;
+	int	nr_find_usage_forwards_recursions;
+	int	nr_find_usage_backwards_checks;
+	int	nr_find_usage_backwards_recursions;
+};
+
+DECLARE_PER_CPU(struct lockdep_stats, lockdep_stats);
+
+#define __debug_atomic_inc(ptr)					\
+	this_cpu_inc(lockdep_stats.ptr);
+
+#define debug_atomic_inc(ptr)			{		\
+	WARN_ON_ONCE(!irqs_disabled());				\
+	__this_cpu_inc(lockdep_stats.ptr);			\
+}
+
+#define debug_atomic_dec(ptr)			{		\
+	WARN_ON_ONCE(!irqs_disabled());				\
+	__this_cpu_dec(lockdep_stats.ptr);			\
+}
+
+#define debug_atomic_read(ptr)		({				\
+	struct lockdep_stats *__cpu_lockdep_stats;			\
+	unsigned long long __total = 0;					\
+	int __cpu;							\
+	for_each_possible_cpu(__cpu) {					\
+		__cpu_lockdep_stats = &per_cpu(lockdep_stats, __cpu);	\
+		__total += __cpu_lockdep_stats->ptr;			\
+	}								\
+	__total;							\
+})
+#else
+# define __debug_atomic_inc(ptr)	do { } while (0)
+# define debug_atomic_inc(ptr)		do { } while (0)
+# define debug_atomic_dec(ptr)		do { } while (0)
+# define debug_atomic_read(ptr)		0
+#endif
diff --git a/kernel/locking/lockdep_proc.c b/kernel/locking/lockdep_proc.c
new file mode 100644
index 000000000..d83d798be
--- /dev/null
+++ b/kernel/locking/lockdep_proc.c
@@ -0,0 +1,695 @@
+/*
+ * kernel/lockdep_proc.c
+ *
+ * Runtime locking correctness validator
+ *
+ * Started by Ingo Molnar:
+ *
+ *  Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
+ *
+ * Code for /proc/lockdep and /proc/lockdep_stats:
+ *
+ */
+#include <linux/export.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/kallsyms.h>
+#include <linux/debug_locks.h>
+#include <linux/vmalloc.h>
+#include <linux/sort.h>
+#include <asm/uaccess.h>
+#include <asm/div64.h>
+
+#include "lockdep_internals.h"
+
+static void *l_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	return seq_list_next(v, &all_lock_classes, pos);
+}
+
+static void *l_start(struct seq_file *m, loff_t *pos)
+{
+	return seq_list_start_head(&all_lock_classes, *pos);
+}
+
+static void l_stop(struct seq_file *m, void *v)
+{
+}
+
+static void print_name(struct seq_file *m, struct lock_class *class)
+{
+	char str[KSYM_NAME_LEN];
+	const char *name = class->name;
+
+	if (!name) {
+		name = __get_key_name(class->key, str);
+		seq_printf(m, "%s", name);
+	} else{
+		seq_printf(m, "%s", name);
+		if (class->name_version > 1)
+			seq_printf(m, "#%d", class->name_version);
+		if (class->subclass)
+			seq_printf(m, "/%d", class->subclass);
+	}
+}
+
+static int l_show(struct seq_file *m, void *v)
+{
+	struct lock_class *class = list_entry(v, struct lock_class, lock_entry);
+	struct lock_list *entry;
+	char usage[LOCK_USAGE_CHARS];
+
+	if (v == &all_lock_classes) {
+		seq_printf(m, "all lock classes:\n");
+		return 0;
+	}
+
+	seq_printf(m, "%p", class->key);
+#ifdef CONFIG_DEBUG_LOCKDEP
+	seq_printf(m, " OPS:%8ld", class->ops);
+#endif
+#ifdef CONFIG_PROVE_LOCKING
+	seq_printf(m, " FD:%5ld", lockdep_count_forward_deps(class));
+	seq_printf(m, " BD:%5ld", lockdep_count_backward_deps(class));
+#endif
+
+	get_usage_chars(class, usage);
+	seq_printf(m, " %s", usage);
+
+	seq_printf(m, ": ");
+	print_name(m, class);
+	seq_puts(m, "\n");
+
+	list_for_each_entry(entry, &class->locks_after, entry) {
+		if (entry->distance == 1) {
+			seq_printf(m, " -> [%p] ", entry->class->key);
+			print_name(m, entry->class);
+			seq_puts(m, "\n");
+		}
+	}
+	seq_puts(m, "\n");
+
+	return 0;
+}
+
+static const struct seq_operations lockdep_ops = {
+	.start	= l_start,
+	.next	= l_next,
+	.stop	= l_stop,
+	.show	= l_show,
+};
+
+static int lockdep_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &lockdep_ops);
+}
+
+static const struct file_operations proc_lockdep_operations = {
+	.open		= lockdep_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+};
+
+#ifdef CONFIG_PROVE_LOCKING
+static void *lc_start(struct seq_file *m, loff_t *pos)
+{
+	if (*pos == 0)
+		return SEQ_START_TOKEN;
+
+	if (*pos - 1 < nr_lock_chains)
+		return lock_chains + (*pos - 1);
+
+	return NULL;
+}
+
+static void *lc_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	(*pos)++;
+	return lc_start(m, pos);
+}
+
+static void lc_stop(struct seq_file *m, void *v)
+{
+}
+
+static int lc_show(struct seq_file *m, void *v)
+{
+	struct lock_chain *chain = v;
+	struct lock_class *class;
+	int i;
+
+	if (v == SEQ_START_TOKEN) {
+		seq_printf(m, "all lock chains:\n");
+		return 0;
+	}
+
+	seq_printf(m, "irq_context: %d\n", chain->irq_context);
+
+	for (i = 0; i < chain->depth; i++) {
+		class = lock_chain_get_class(chain, i);
+		if (!class->key)
+			continue;
+
+		seq_printf(m, "[%p] ", class->key);
+		print_name(m, class);
+		seq_puts(m, "\n");
+	}
+	seq_puts(m, "\n");
+
+	return 0;
+}
+
+static const struct seq_operations lockdep_chains_ops = {
+	.start	= lc_start,
+	.next	= lc_next,
+	.stop	= lc_stop,
+	.show	= lc_show,
+};
+
+static int lockdep_chains_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &lockdep_chains_ops);
+}
+
+static const struct file_operations proc_lockdep_chains_operations = {
+	.open		= lockdep_chains_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+};
+#endif /* CONFIG_PROVE_LOCKING */
+
+static void lockdep_stats_debug_show(struct seq_file *m)
+{
+#ifdef CONFIG_DEBUG_LOCKDEP
+	unsigned long long hi1 = debug_atomic_read(hardirqs_on_events),
+			   hi2 = debug_atomic_read(hardirqs_off_events),
+			   hr1 = debug_atomic_read(redundant_hardirqs_on),
+			   hr2 = debug_atomic_read(redundant_hardirqs_off),
+			   si1 = debug_atomic_read(softirqs_on_events),
+			   si2 = debug_atomic_read(softirqs_off_events),
+			   sr1 = debug_atomic_read(redundant_softirqs_on),
+			   sr2 = debug_atomic_read(redundant_softirqs_off);
+
+	seq_printf(m, " chain lookup misses:           %11llu\n",
+		debug_atomic_read(chain_lookup_misses));
+	seq_printf(m, " chain lookup hits:             %11llu\n",
+		debug_atomic_read(chain_lookup_hits));
+	seq_printf(m, " cyclic checks:                 %11llu\n",
+		debug_atomic_read(nr_cyclic_checks));
+	seq_printf(m, " find-mask forwards checks:     %11llu\n",
+		debug_atomic_read(nr_find_usage_forwards_checks));
+	seq_printf(m, " find-mask backwards checks:    %11llu\n",
+		debug_atomic_read(nr_find_usage_backwards_checks));
+
+	seq_printf(m, " hardirq on events:             %11llu\n", hi1);
+	seq_printf(m, " hardirq off events:            %11llu\n", hi2);
+	seq_printf(m, " redundant hardirq ons:         %11llu\n", hr1);
+	seq_printf(m, " redundant hardirq offs:        %11llu\n", hr2);
+	seq_printf(m, " softirq on events:             %11llu\n", si1);
+	seq_printf(m, " softirq off events:            %11llu\n", si2);
+	seq_printf(m, " redundant softirq ons:         %11llu\n", sr1);
+	seq_printf(m, " redundant softirq offs:        %11llu\n", sr2);
+#endif
+}
+
+static int lockdep_stats_show(struct seq_file *m, void *v)
+{
+	struct lock_class *class;
+	unsigned long nr_unused = 0, nr_uncategorized = 0,
+		      nr_irq_safe = 0, nr_irq_unsafe = 0,
+		      nr_softirq_safe = 0, nr_softirq_unsafe = 0,
+		      nr_hardirq_safe = 0, nr_hardirq_unsafe = 0,
+		      nr_irq_read_safe = 0, nr_irq_read_unsafe = 0,
+		      nr_softirq_read_safe = 0, nr_softirq_read_unsafe = 0,
+		      nr_hardirq_read_safe = 0, nr_hardirq_read_unsafe = 0,
+		      sum_forward_deps = 0;
+
+	list_for_each_entry(class, &all_lock_classes, lock_entry) {
+
+		if (class->usage_mask == 0)
+			nr_unused++;
+		if (class->usage_mask == LOCKF_USED)
+			nr_uncategorized++;
+		if (class->usage_mask & LOCKF_USED_IN_IRQ)
+			nr_irq_safe++;
+		if (class->usage_mask & LOCKF_ENABLED_IRQ)
+			nr_irq_unsafe++;
+		if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
+			nr_softirq_safe++;
+		if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ)
+			nr_softirq_unsafe++;
+		if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
+			nr_hardirq_safe++;
+		if (class->usage_mask & LOCKF_ENABLED_HARDIRQ)
+			nr_hardirq_unsafe++;
+		if (class->usage_mask & LOCKF_USED_IN_IRQ_READ)
+			nr_irq_read_safe++;
+		if (class->usage_mask & LOCKF_ENABLED_IRQ_READ)
+			nr_irq_read_unsafe++;
+		if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ)
+			nr_softirq_read_safe++;
+		if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ_READ)
+			nr_softirq_read_unsafe++;
+		if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ)
+			nr_hardirq_read_safe++;
+		if (class->usage_mask & LOCKF_ENABLED_HARDIRQ_READ)
+			nr_hardirq_read_unsafe++;
+
+#ifdef CONFIG_PROVE_LOCKING
+		sum_forward_deps += lockdep_count_forward_deps(class);
+#endif
+	}
+#ifdef CONFIG_DEBUG_LOCKDEP
+	DEBUG_LOCKS_WARN_ON(debug_atomic_read(nr_unused_locks) != nr_unused);
+#endif
+	seq_printf(m, " lock-classes:                  %11lu [max: %lu]\n",
+			nr_lock_classes, MAX_LOCKDEP_KEYS);
+	seq_printf(m, " direct dependencies:           %11lu [max: %lu]\n",
+			nr_list_entries, MAX_LOCKDEP_ENTRIES);
+	seq_printf(m, " indirect dependencies:         %11lu\n",
+			sum_forward_deps);
+
+	/*
+	 * Total number of dependencies:
+	 *
+	 * All irq-safe locks may nest inside irq-unsafe locks,
+	 * plus all the other known dependencies:
+	 */
+	seq_printf(m, " all direct dependencies:       %11lu\n",
+			nr_irq_unsafe * nr_irq_safe +
+			nr_hardirq_unsafe * nr_hardirq_safe +
+			nr_list_entries);
+
+#ifdef CONFIG_PROVE_LOCKING
+	seq_printf(m, " dependency chains:             %11lu [max: %lu]\n",
+			nr_lock_chains, MAX_LOCKDEP_CHAINS);
+	seq_printf(m, " dependency chain hlocks:       %11d [max: %lu]\n",
+			nr_chain_hlocks, MAX_LOCKDEP_CHAIN_HLOCKS);
+#endif
+
+#ifdef CONFIG_TRACE_IRQFLAGS
+	seq_printf(m, " in-hardirq chains:             %11u\n",
+			nr_hardirq_chains);
+	seq_printf(m, " in-softirq chains:             %11u\n",
+			nr_softirq_chains);
+#endif
+	seq_printf(m, " in-process chains:             %11u\n",
+			nr_process_chains);
+	seq_printf(m, " stack-trace entries:           %11lu [max: %lu]\n",
+			nr_stack_trace_entries, MAX_STACK_TRACE_ENTRIES);
+	seq_printf(m, " combined max dependencies:     %11u\n",
+			(nr_hardirq_chains + 1) *
+			(nr_softirq_chains + 1) *
+			(nr_process_chains + 1)
+	);
+	seq_printf(m, " hardirq-safe locks:            %11lu\n",
+			nr_hardirq_safe);
+	seq_printf(m, " hardirq-unsafe locks:          %11lu\n",
+			nr_hardirq_unsafe);
+	seq_printf(m, " softirq-safe locks:            %11lu\n",
+			nr_softirq_safe);
+	seq_printf(m, " softirq-unsafe locks:          %11lu\n",
+			nr_softirq_unsafe);
+	seq_printf(m, " irq-safe locks:                %11lu\n",
+			nr_irq_safe);
+	seq_printf(m, " irq-unsafe locks:              %11lu\n",
+			nr_irq_unsafe);
+
+	seq_printf(m, " hardirq-read-safe locks:       %11lu\n",
+			nr_hardirq_read_safe);
+	seq_printf(m, " hardirq-read-unsafe locks:     %11lu\n",
+			nr_hardirq_read_unsafe);
+	seq_printf(m, " softirq-read-safe locks:       %11lu\n",
+			nr_softirq_read_safe);
+	seq_printf(m, " softirq-read-unsafe locks:     %11lu\n",
+			nr_softirq_read_unsafe);
+	seq_printf(m, " irq-read-safe locks:           %11lu\n",
+			nr_irq_read_safe);
+	seq_printf(m, " irq-read-unsafe locks:         %11lu\n",
+			nr_irq_read_unsafe);
+
+	seq_printf(m, " uncategorized locks:           %11lu\n",
+			nr_uncategorized);
+	seq_printf(m, " unused locks:                  %11lu\n",
+			nr_unused);
+	seq_printf(m, " max locking depth:             %11u\n",
+			max_lockdep_depth);
+#ifdef CONFIG_PROVE_LOCKING
+	seq_printf(m, " max bfs queue depth:           %11u\n",
+			max_bfs_queue_depth);
+#endif
+	lockdep_stats_debug_show(m);
+	seq_printf(m, " debug_locks:                   %11u\n",
+			debug_locks);
+
+	return 0;
+}
+
+static int lockdep_stats_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, lockdep_stats_show, NULL);
+}
+
+static const struct file_operations proc_lockdep_stats_operations = {
+	.open		= lockdep_stats_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+#ifdef CONFIG_LOCK_STAT
+
+struct lock_stat_data {
+	struct lock_class *class;
+	struct lock_class_stats stats;
+};
+
+struct lock_stat_seq {
+	struct lock_stat_data *iter_end;
+	struct lock_stat_data stats[MAX_LOCKDEP_KEYS];
+};
+
+/*
+ * sort on absolute number of contentions
+ */
+static int lock_stat_cmp(const void *l, const void *r)
+{
+	const struct lock_stat_data *dl = l, *dr = r;
+	unsigned long nl, nr;
+
+	nl = dl->stats.read_waittime.nr + dl->stats.write_waittime.nr;
+	nr = dr->stats.read_waittime.nr + dr->stats.write_waittime.nr;
+
+	return nr - nl;
+}
+
+static void seq_line(struct seq_file *m, char c, int offset, int length)
+{
+	int i;
+
+	for (i = 0; i < offset; i++)
+		seq_puts(m, " ");
+	for (i = 0; i < length; i++)
+		seq_printf(m, "%c", c);
+	seq_puts(m, "\n");
+}
+
+static void snprint_time(char *buf, size_t bufsiz, s64 nr)
+{
+	s64 div;
+	s32 rem;
+
+	nr += 5; /* for display rounding */
+	div = div_s64_rem(nr, 1000, &rem);
+	snprintf(buf, bufsiz, "%lld.%02d", (long long)div, (int)rem/10);
+}
+
+static void seq_time(struct seq_file *m, s64 time)
+{
+	char num[15];
+
+	snprint_time(num, sizeof(num), time);
+	seq_printf(m, " %14s", num);
+}
+
+static void seq_lock_time(struct seq_file *m, struct lock_time *lt)
+{
+	seq_printf(m, "%14lu", lt->nr);
+	seq_time(m, lt->min);
+	seq_time(m, lt->max);
+	seq_time(m, lt->total);
+	seq_time(m, lt->nr ? div_s64(lt->total, lt->nr) : 0);
+}
+
+static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
+{
+	struct lockdep_subclass_key *ckey;
+	struct lock_class_stats *stats;
+	struct lock_class *class;
+	const char *cname;
+	int i, namelen;
+	char name[39];
+
+	class = data->class;
+	stats = &data->stats;
+
+	namelen = 38;
+	if (class->name_version > 1)
+		namelen -= 2; /* XXX truncates versions > 9 */
+	if (class->subclass)
+		namelen -= 2;
+
+	rcu_read_lock_sched();
+	cname = rcu_dereference_sched(class->name);
+	ckey  = rcu_dereference_sched(class->key);
+
+	if (!cname && !ckey) {
+		rcu_read_unlock_sched();
+		return;
+
+	} else if (!cname) {
+		char str[KSYM_NAME_LEN];
+		const char *key_name;
+
+		key_name = __get_key_name(ckey, str);
+		snprintf(name, namelen, "%s", key_name);
+	} else {
+		snprintf(name, namelen, "%s", cname);
+	}
+	rcu_read_unlock_sched();
+
+	namelen = strlen(name);
+	if (class->name_version > 1) {
+		snprintf(name+namelen, 3, "#%d", class->name_version);
+		namelen += 2;
+	}
+	if (class->subclass) {
+		snprintf(name+namelen, 3, "/%d", class->subclass);
+		namelen += 2;
+	}
+
+	if (stats->write_holdtime.nr) {
+		if (stats->read_holdtime.nr)
+			seq_printf(m, "%38s-W:", name);
+		else
+			seq_printf(m, "%40s:", name);
+
+		seq_printf(m, "%14lu ", stats->bounces[bounce_contended_write]);
+		seq_lock_time(m, &stats->write_waittime);
+		seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_write]);
+		seq_lock_time(m, &stats->write_holdtime);
+		seq_puts(m, "\n");
+	}
+
+	if (stats->read_holdtime.nr) {
+		seq_printf(m, "%38s-R:", name);
+		seq_printf(m, "%14lu ", stats->bounces[bounce_contended_read]);
+		seq_lock_time(m, &stats->read_waittime);
+		seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_read]);
+		seq_lock_time(m, &stats->read_holdtime);
+		seq_puts(m, "\n");
+	}
+
+	if (stats->read_waittime.nr + stats->write_waittime.nr == 0)
+		return;
+
+	if (stats->read_holdtime.nr)
+		namelen += 2;
+
+	for (i = 0; i < LOCKSTAT_POINTS; i++) {
+		char ip[32];
+
+		if (class->contention_point[i] == 0)
+			break;
+
+		if (!i)
+			seq_line(m, '-', 40-namelen, namelen);
+
+		snprintf(ip, sizeof(ip), "[<%p>]",
+				(void *)class->contention_point[i]);
+		seq_printf(m, "%40s %14lu %29s %pS\n",
+			   name, stats->contention_point[i],
+			   ip, (void *)class->contention_point[i]);
+	}
+	for (i = 0; i < LOCKSTAT_POINTS; i++) {
+		char ip[32];
+
+		if (class->contending_point[i] == 0)
+			break;
+
+		if (!i)
+			seq_line(m, '-', 40-namelen, namelen);
+
+		snprintf(ip, sizeof(ip), "[<%p>]",
+				(void *)class->contending_point[i]);
+		seq_printf(m, "%40s %14lu %29s %pS\n",
+			   name, stats->contending_point[i],
+			   ip, (void *)class->contending_point[i]);
+	}
+	if (i) {
+		seq_puts(m, "\n");
+		seq_line(m, '.', 0, 40 + 1 + 12 * (14 + 1));
+		seq_puts(m, "\n");
+	}
+}
+
+static void seq_header(struct seq_file *m)
+{
+	seq_puts(m, "lock_stat version 0.4\n");
+
+	if (unlikely(!debug_locks))
+		seq_printf(m, "*WARNING* lock debugging disabled!! - possibly due to a lockdep warning\n");
+
+	seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1));
+	seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s %14s %14s "
+			"%14s %14s\n",
+			"class name",
+			"con-bounces",
+			"contentions",
+			"waittime-min",
+			"waittime-max",
+			"waittime-total",
+			"waittime-avg",
+			"acq-bounces",
+			"acquisitions",
+			"holdtime-min",
+			"holdtime-max",
+			"holdtime-total",
+			"holdtime-avg");
+	seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1));
+	seq_printf(m, "\n");
+}
+
+static void *ls_start(struct seq_file *m, loff_t *pos)
+{
+	struct lock_stat_seq *data = m->private;
+	struct lock_stat_data *iter;
+
+	if (*pos == 0)
+		return SEQ_START_TOKEN;
+
+	iter = data->stats + (*pos - 1);
+	if (iter >= data->iter_end)
+		iter = NULL;
+
+	return iter;
+}
+
+static void *ls_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	(*pos)++;
+	return ls_start(m, pos);
+}
+
+static void ls_stop(struct seq_file *m, void *v)
+{
+}
+
+static int ls_show(struct seq_file *m, void *v)
+{
+	if (v == SEQ_START_TOKEN)
+		seq_header(m);
+	else
+		seq_stats(m, v);
+
+	return 0;
+}
+
+static const struct seq_operations lockstat_ops = {
+	.start	= ls_start,
+	.next	= ls_next,
+	.stop	= ls_stop,
+	.show	= ls_show,
+};
+
+static int lock_stat_open(struct inode *inode, struct file *file)
+{
+	int res;
+	struct lock_class *class;
+	struct lock_stat_seq *data = vmalloc(sizeof(struct lock_stat_seq));
+
+	if (!data)
+		return -ENOMEM;
+
+	res = seq_open(file, &lockstat_ops);
+	if (!res) {
+		struct lock_stat_data *iter = data->stats;
+		struct seq_file *m = file->private_data;
+
+		list_for_each_entry(class, &all_lock_classes, lock_entry) {
+			iter->class = class;
+			iter->stats = lock_stats(class);
+			iter++;
+		}
+		data->iter_end = iter;
+
+		sort(data->stats, data->iter_end - data->stats,
+				sizeof(struct lock_stat_data),
+				lock_stat_cmp, NULL);
+
+		m->private = data;
+	} else
+		vfree(data);
+
+	return res;
+}
+
+static ssize_t lock_stat_write(struct file *file, const char __user *buf,
+			       size_t count, loff_t *ppos)
+{
+	struct lock_class *class;
+	char c;
+
+	if (count) {
+		if (get_user(c, buf))
+			return -EFAULT;
+
+		if (c != '0')
+			return count;
+
+		list_for_each_entry(class, &all_lock_classes, lock_entry)
+			clear_lock_stats(class);
+	}
+	return count;
+}
+
+static int lock_stat_release(struct inode *inode, struct file *file)
+{
+	struct seq_file *seq = file->private_data;
+
+	vfree(seq->private);
+	return seq_release(inode, file);
+}
+
+static const struct file_operations proc_lock_stat_operations = {
+	.open		= lock_stat_open,
+	.write		= lock_stat_write,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= lock_stat_release,
+};
+#endif /* CONFIG_LOCK_STAT */
+
+static int __init lockdep_proc_init(void)
+{
+	proc_create("lockdep", S_IRUSR, NULL, &proc_lockdep_operations);
+#ifdef CONFIG_PROVE_LOCKING
+	proc_create("lockdep_chains", S_IRUSR, NULL,
+		    &proc_lockdep_chains_operations);
+#endif
+	proc_create("lockdep_stats", S_IRUSR, NULL,
+		    &proc_lockdep_stats_operations);
+
+#ifdef CONFIG_LOCK_STAT
+	proc_create("lock_stat", S_IRUSR | S_IWUSR, NULL,
+		    &proc_lock_stat_operations);
+#endif
+
+	return 0;
+}
+
+__initcall(lockdep_proc_init);
+
diff --git a/kernel/locking/lockdep_states.h b/kernel/locking/lockdep_states.h
new file mode 100644
index 000000000..995b0cc2b
--- /dev/null
+++ b/kernel/locking/lockdep_states.h
@@ -0,0 +1,9 @@
+/*
+ * Lockdep states,
+ *
+ * please update XXX_LOCK_USAGE_STATES in include/linux/lockdep.h whenever
+ * you add one, or come up with a nice dynamic solution.
+ */
+LOCKDEP_STATE(HARDIRQ)
+LOCKDEP_STATE(SOFTIRQ)
+LOCKDEP_STATE(RECLAIM_FS)
diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
new file mode 100644
index 000000000..ec8cce259
--- /dev/null
+++ b/kernel/locking/locktorture.c
@@ -0,0 +1,815 @@
+/*
+ * Module-based torture test facility for locking
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, you can access it online at
+ * http://www.gnu.org/licenses/gpl-2.0.html.
+ *
+ * Copyright (C) IBM Corporation, 2014
+ *
+ * Author: Paul E. McKenney <paulmck@us.ibm.com>
+ *	Based on kernel/rcu/torture.c.
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/kthread.h>
+#include <linux/spinlock.h>
+#include <linux/rwlock.h>
+#include <linux/mutex.h>
+#include <linux/rwsem.h>
+#include <linux/smp.h>
+#include <linux/interrupt.h>
+#include <linux/sched.h>
+#include <linux/atomic.h>
+#include <linux/moduleparam.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/torture.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com>");
+
+torture_param(int, nwriters_stress, -1,
+	     "Number of write-locking stress-test threads");
+torture_param(int, nreaders_stress, -1,
+	     "Number of read-locking stress-test threads");
+torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
+torture_param(int, onoff_interval, 0,
+	     "Time between CPU hotplugs (s), 0=disable");
+torture_param(int, shuffle_interval, 3,
+	     "Number of jiffies between shuffles, 0=disable");
+torture_param(int, shutdown_secs, 0, "Shutdown time (j), <= zero to disable.");
+torture_param(int, stat_interval, 60,
+	     "Number of seconds between stats printk()s");
+torture_param(int, stutter, 5, "Number of jiffies to run/halt test, 0=disable");
+torture_param(bool, verbose, true,
+	     "Enable verbose debugging printk()s");
+
+static char *torture_type = "spin_lock";
+module_param(torture_type, charp, 0444);
+MODULE_PARM_DESC(torture_type,
+		 "Type of lock to torture (spin_lock, spin_lock_irq, mutex_lock, ...)");
+
+static struct task_struct *stats_task;
+static struct task_struct **writer_tasks;
+static struct task_struct **reader_tasks;
+
+static bool lock_is_write_held;
+static bool lock_is_read_held;
+
+struct lock_stress_stats {
+	long n_lock_fail;
+	long n_lock_acquired;
+};
+
+#if defined(MODULE)
+#define LOCKTORTURE_RUNNABLE_INIT 1
+#else
+#define LOCKTORTURE_RUNNABLE_INIT 0
+#endif
+int torture_runnable = LOCKTORTURE_RUNNABLE_INIT;
+module_param(torture_runnable, int, 0444);
+MODULE_PARM_DESC(torture_runnable, "Start locktorture at module init");
+
+/* Forward reference. */
+static void lock_torture_cleanup(void);
+
+/*
+ * Operations vector for selecting different types of tests.
+ */
+struct lock_torture_ops {
+	void (*init)(void);
+	int (*writelock)(void);
+	void (*write_delay)(struct torture_random_state *trsp);
+	void (*writeunlock)(void);
+	int (*readlock)(void);
+	void (*read_delay)(struct torture_random_state *trsp);
+	void (*readunlock)(void);
+	unsigned long flags;
+	const char *name;
+};
+
+struct lock_torture_cxt {
+	int nrealwriters_stress;
+	int nrealreaders_stress;
+	bool debug_lock;
+	atomic_t n_lock_torture_errors;
+	struct lock_torture_ops *cur_ops;
+	struct lock_stress_stats *lwsa; /* writer statistics */
+	struct lock_stress_stats *lrsa; /* reader statistics */
+};
+static struct lock_torture_cxt cxt = { 0, 0, false,
+				       ATOMIC_INIT(0),
+				       NULL, NULL};
+/*
+ * Definitions for lock torture testing.
+ */
+
+static int torture_lock_busted_write_lock(void)
+{
+	return 0;  /* BUGGY, do not use in real life!!! */
+}
+
+static void torture_lock_busted_write_delay(struct torture_random_state *trsp)
+{
+	const unsigned long longdelay_us = 100;
+
+	/* We want a long delay occasionally to force massive contention.  */
+	if (!(torture_random(trsp) %
+	      (cxt.nrealwriters_stress * 2000 * longdelay_us)))
+		mdelay(longdelay_us);
+#ifdef CONFIG_PREEMPT
+	if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
+		preempt_schedule();  /* Allow test to be preempted. */
+#endif
+}
+
+static void torture_lock_busted_write_unlock(void)
+{
+	  /* BUGGY, do not use in real life!!! */
+}
+
+static struct lock_torture_ops lock_busted_ops = {
+	.writelock	= torture_lock_busted_write_lock,
+	.write_delay	= torture_lock_busted_write_delay,
+	.writeunlock	= torture_lock_busted_write_unlock,
+	.readlock       = NULL,
+	.read_delay     = NULL,
+	.readunlock     = NULL,
+	.name		= "lock_busted"
+};
+
+static DEFINE_SPINLOCK(torture_spinlock);
+
+static int torture_spin_lock_write_lock(void) __acquires(torture_spinlock)
+{
+	spin_lock(&torture_spinlock);
+	return 0;
+}
+
+static void torture_spin_lock_write_delay(struct torture_random_state *trsp)
+{
+	const unsigned long shortdelay_us = 2;
+	const unsigned long longdelay_us = 100;
+
+	/* We want a short delay mostly to emulate likely code, and
+	 * we want a long delay occasionally to force massive contention.
+	 */
+	if (!(torture_random(trsp) %
+	      (cxt.nrealwriters_stress * 2000 * longdelay_us)))
+		mdelay(longdelay_us);
+	if (!(torture_random(trsp) %
+	      (cxt.nrealwriters_stress * 2 * shortdelay_us)))
+		udelay(shortdelay_us);
+#ifdef CONFIG_PREEMPT
+	if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
+		preempt_schedule();  /* Allow test to be preempted. */
+#endif
+}
+
+static void torture_spin_lock_write_unlock(void) __releases(torture_spinlock)
+{
+	spin_unlock(&torture_spinlock);
+}
+
+static struct lock_torture_ops spin_lock_ops = {
+	.writelock	= torture_spin_lock_write_lock,
+	.write_delay	= torture_spin_lock_write_delay,
+	.writeunlock	= torture_spin_lock_write_unlock,
+	.readlock       = NULL,
+	.read_delay     = NULL,
+	.readunlock     = NULL,
+	.name		= "spin_lock"
+};
+
+static int torture_spin_lock_write_lock_irq(void)
+__acquires(torture_spinlock)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&torture_spinlock, flags);
+	cxt.cur_ops->flags = flags;
+	return 0;
+}
+
+static void torture_lock_spin_write_unlock_irq(void)
+__releases(torture_spinlock)
+{
+	spin_unlock_irqrestore(&torture_spinlock, cxt.cur_ops->flags);
+}
+
+static struct lock_torture_ops spin_lock_irq_ops = {
+	.writelock	= torture_spin_lock_write_lock_irq,
+	.write_delay	= torture_spin_lock_write_delay,
+	.writeunlock	= torture_lock_spin_write_unlock_irq,
+	.readlock       = NULL,
+	.read_delay     = NULL,
+	.readunlock     = NULL,
+	.name		= "spin_lock_irq"
+};
+
+static DEFINE_RWLOCK(torture_rwlock);
+
+static int torture_rwlock_write_lock(void) __acquires(torture_rwlock)
+{
+	write_lock(&torture_rwlock);
+	return 0;
+}
+
+static void torture_rwlock_write_delay(struct torture_random_state *trsp)
+{
+	const unsigned long shortdelay_us = 2;
+	const unsigned long longdelay_ms = 100;
+
+	/* We want a short delay mostly to emulate likely code, and
+	 * we want a long delay occasionally to force massive contention.
+	 */
+	if (!(torture_random(trsp) %
+	      (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
+		mdelay(longdelay_ms);
+	else
+		udelay(shortdelay_us);
+}
+
+static void torture_rwlock_write_unlock(void) __releases(torture_rwlock)
+{
+	write_unlock(&torture_rwlock);
+}
+
+static int torture_rwlock_read_lock(void) __acquires(torture_rwlock)
+{
+	read_lock(&torture_rwlock);
+	return 0;
+}
+
+static void torture_rwlock_read_delay(struct torture_random_state *trsp)
+{
+	const unsigned long shortdelay_us = 10;
+	const unsigned long longdelay_ms = 100;
+
+	/* We want a short delay mostly to emulate likely code, and
+	 * we want a long delay occasionally to force massive contention.
+	 */
+	if (!(torture_random(trsp) %
+	      (cxt.nrealreaders_stress * 2000 * longdelay_ms)))
+		mdelay(longdelay_ms);
+	else
+		udelay(shortdelay_us);
+}
+
+static void torture_rwlock_read_unlock(void) __releases(torture_rwlock)
+{
+	read_unlock(&torture_rwlock);
+}
+
+static struct lock_torture_ops rw_lock_ops = {
+	.writelock	= torture_rwlock_write_lock,
+	.write_delay	= torture_rwlock_write_delay,
+	.writeunlock	= torture_rwlock_write_unlock,
+	.readlock       = torture_rwlock_read_lock,
+	.read_delay     = torture_rwlock_read_delay,
+	.readunlock     = torture_rwlock_read_unlock,
+	.name		= "rw_lock"
+};
+
+static int torture_rwlock_write_lock_irq(void) __acquires(torture_rwlock)
+{
+	unsigned long flags;
+
+	write_lock_irqsave(&torture_rwlock, flags);
+	cxt.cur_ops->flags = flags;
+	return 0;
+}
+
+static void torture_rwlock_write_unlock_irq(void)
+__releases(torture_rwlock)
+{
+	write_unlock_irqrestore(&torture_rwlock, cxt.cur_ops->flags);
+}
+
+static int torture_rwlock_read_lock_irq(void) __acquires(torture_rwlock)
+{
+	unsigned long flags;
+
+	read_lock_irqsave(&torture_rwlock, flags);
+	cxt.cur_ops->flags = flags;
+	return 0;
+}
+
+static void torture_rwlock_read_unlock_irq(void)
+__releases(torture_rwlock)
+{
+	write_unlock_irqrestore(&torture_rwlock, cxt.cur_ops->flags);
+}
+
+static struct lock_torture_ops rw_lock_irq_ops = {
+	.writelock	= torture_rwlock_write_lock_irq,
+	.write_delay	= torture_rwlock_write_delay,
+	.writeunlock	= torture_rwlock_write_unlock_irq,
+	.readlock       = torture_rwlock_read_lock_irq,
+	.read_delay     = torture_rwlock_read_delay,
+	.readunlock     = torture_rwlock_read_unlock_irq,
+	.name		= "rw_lock_irq"
+};
+
+static DEFINE_MUTEX(torture_mutex);
+
+static int torture_mutex_lock(void) __acquires(torture_mutex)
+{
+	mutex_lock(&torture_mutex);
+	return 0;
+}
+
+static void torture_mutex_delay(struct torture_random_state *trsp)
+{
+	const unsigned long longdelay_ms = 100;
+
+	/* We want a long delay occasionally to force massive contention.  */
+	if (!(torture_random(trsp) %
+	      (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
+		mdelay(longdelay_ms * 5);
+	else
+		mdelay(longdelay_ms / 5);
+#ifdef CONFIG_PREEMPT
+	if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
+		preempt_schedule();  /* Allow test to be preempted. */
+#endif
+}
+
+static void torture_mutex_unlock(void) __releases(torture_mutex)
+{
+	mutex_unlock(&torture_mutex);
+}
+
+static struct lock_torture_ops mutex_lock_ops = {
+	.writelock	= torture_mutex_lock,
+	.write_delay	= torture_mutex_delay,
+	.writeunlock	= torture_mutex_unlock,
+	.readlock       = NULL,
+	.read_delay     = NULL,
+	.readunlock     = NULL,
+	.name		= "mutex_lock"
+};
+
+static DECLARE_RWSEM(torture_rwsem);
+static int torture_rwsem_down_write(void) __acquires(torture_rwsem)
+{
+	down_write(&torture_rwsem);
+	return 0;
+}
+
+static void torture_rwsem_write_delay(struct torture_random_state *trsp)
+{
+	const unsigned long longdelay_ms = 100;
+
+	/* We want a long delay occasionally to force massive contention.  */
+	if (!(torture_random(trsp) %
+	      (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
+		mdelay(longdelay_ms * 10);
+	else
+		mdelay(longdelay_ms / 10);
+#ifdef CONFIG_PREEMPT
+	if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
+		preempt_schedule();  /* Allow test to be preempted. */
+#endif
+}
+
+static void torture_rwsem_up_write(void) __releases(torture_rwsem)
+{
+	up_write(&torture_rwsem);
+}
+
+static int torture_rwsem_down_read(void) __acquires(torture_rwsem)
+{
+	down_read(&torture_rwsem);
+	return 0;
+}
+
+static void torture_rwsem_read_delay(struct torture_random_state *trsp)
+{
+	const unsigned long longdelay_ms = 100;
+
+	/* We want a long delay occasionally to force massive contention.  */
+	if (!(torture_random(trsp) %
+	      (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
+		mdelay(longdelay_ms * 2);
+	else
+		mdelay(longdelay_ms / 2);
+#ifdef CONFIG_PREEMPT
+	if (!(torture_random(trsp) % (cxt.nrealreaders_stress * 20000)))
+		preempt_schedule();  /* Allow test to be preempted. */
+#endif
+}
+
+static void torture_rwsem_up_read(void) __releases(torture_rwsem)
+{
+	up_read(&torture_rwsem);
+}
+
+static struct lock_torture_ops rwsem_lock_ops = {
+	.writelock	= torture_rwsem_down_write,
+	.write_delay	= torture_rwsem_write_delay,
+	.writeunlock	= torture_rwsem_up_write,
+	.readlock       = torture_rwsem_down_read,
+	.read_delay     = torture_rwsem_read_delay,
+	.readunlock     = torture_rwsem_up_read,
+	.name		= "rwsem_lock"
+};
+
+/*
+ * Lock torture writer kthread.  Repeatedly acquires and releases
+ * the lock, checking for duplicate acquisitions.
+ */
+static int lock_torture_writer(void *arg)
+{
+	struct lock_stress_stats *lwsp = arg;
+	static DEFINE_TORTURE_RANDOM(rand);
+
+	VERBOSE_TOROUT_STRING("lock_torture_writer task started");
+	set_user_nice(current, MAX_NICE);
+
+	do {
+		if ((torture_random(&rand) & 0xfffff) == 0)
+			schedule_timeout_uninterruptible(1);
+
+		cxt.cur_ops->writelock();
+		if (WARN_ON_ONCE(lock_is_write_held))
+			lwsp->n_lock_fail++;
+		lock_is_write_held = 1;
+		if (WARN_ON_ONCE(lock_is_read_held))
+			lwsp->n_lock_fail++; /* rare, but... */
+
+		lwsp->n_lock_acquired++;
+		cxt.cur_ops->write_delay(&rand);
+		lock_is_write_held = 0;
+		cxt.cur_ops->writeunlock();
+
+		stutter_wait("lock_torture_writer");
+	} while (!torture_must_stop());
+	torture_kthread_stopping("lock_torture_writer");
+	return 0;
+}
+
+/*
+ * Lock torture reader kthread.  Repeatedly acquires and releases
+ * the reader lock.
+ */
+static int lock_torture_reader(void *arg)
+{
+	struct lock_stress_stats *lrsp = arg;
+	static DEFINE_TORTURE_RANDOM(rand);
+
+	VERBOSE_TOROUT_STRING("lock_torture_reader task started");
+	set_user_nice(current, MAX_NICE);
+
+	do {
+		if ((torture_random(&rand) & 0xfffff) == 0)
+			schedule_timeout_uninterruptible(1);
+
+		cxt.cur_ops->readlock();
+		lock_is_read_held = 1;
+		if (WARN_ON_ONCE(lock_is_write_held))
+			lrsp->n_lock_fail++; /* rare, but... */
+
+		lrsp->n_lock_acquired++;
+		cxt.cur_ops->read_delay(&rand);
+		lock_is_read_held = 0;
+		cxt.cur_ops->readunlock();
+
+		stutter_wait("lock_torture_reader");
+	} while (!torture_must_stop());
+	torture_kthread_stopping("lock_torture_reader");
+	return 0;
+}
+
+/*
+ * Create an lock-torture-statistics message in the specified buffer.
+ */
+static void __torture_print_stats(char *page,
+				  struct lock_stress_stats *statp, bool write)
+{
+	bool fail = 0;
+	int i, n_stress;
+	long max = 0;
+	long min = statp[0].n_lock_acquired;
+	long long sum = 0;
+
+	n_stress = write ? cxt.nrealwriters_stress : cxt.nrealreaders_stress;
+	for (i = 0; i < n_stress; i++) {
+		if (statp[i].n_lock_fail)
+			fail = true;
+		sum += statp[i].n_lock_acquired;
+		if (max < statp[i].n_lock_fail)
+			max = statp[i].n_lock_fail;
+		if (min > statp[i].n_lock_fail)
+			min = statp[i].n_lock_fail;
+	}
+	page += sprintf(page,
+			"%s:  Total: %lld  Max/Min: %ld/%ld %s  Fail: %d %s\n",
+			write ? "Writes" : "Reads ",
+			sum, max, min, max / 2 > min ? "???" : "",
+			fail, fail ? "!!!" : "");
+	if (fail)
+		atomic_inc(&cxt.n_lock_torture_errors);
+}
+
+/*
+ * Print torture statistics.  Caller must ensure that there is only one
+ * call to this function at a given time!!!  This is normally accomplished
+ * by relying on the module system to only have one copy of the module
+ * loaded, and then by giving the lock_torture_stats kthread full control
+ * (or the init/cleanup functions when lock_torture_stats thread is not
+ * running).
+ */
+static void lock_torture_stats_print(void)
+{
+	int size = cxt.nrealwriters_stress * 200 + 8192;
+	char *buf;
+
+	if (cxt.cur_ops->readlock)
+		size += cxt.nrealreaders_stress * 200 + 8192;
+
+	buf = kmalloc(size, GFP_KERNEL);
+	if (!buf) {
+		pr_err("lock_torture_stats_print: Out of memory, need: %d",
+		       size);
+		return;
+	}
+
+	__torture_print_stats(buf, cxt.lwsa, true);
+	pr_alert("%s", buf);
+	kfree(buf);
+
+	if (cxt.cur_ops->readlock) {
+		buf = kmalloc(size, GFP_KERNEL);
+		if (!buf) {
+			pr_err("lock_torture_stats_print: Out of memory, need: %d",
+			       size);
+			return;
+		}
+
+		__torture_print_stats(buf, cxt.lrsa, false);
+		pr_alert("%s", buf);
+		kfree(buf);
+	}
+}
+
+/*
+ * Periodically prints torture statistics, if periodic statistics printing
+ * was specified via the stat_interval module parameter.
+ *
+ * No need to worry about fullstop here, since this one doesn't reference
+ * volatile state or register callbacks.
+ */
+static int lock_torture_stats(void *arg)
+{
+	VERBOSE_TOROUT_STRING("lock_torture_stats task started");
+	do {
+		schedule_timeout_interruptible(stat_interval * HZ);
+		lock_torture_stats_print();
+		torture_shutdown_absorb("lock_torture_stats");
+	} while (!torture_must_stop());
+	torture_kthread_stopping("lock_torture_stats");
+	return 0;
+}
+
+static inline void
+lock_torture_print_module_parms(struct lock_torture_ops *cur_ops,
+				const char *tag)
+{
+	pr_alert("%s" TORTURE_FLAG
+		 "--- %s%s: nwriters_stress=%d nreaders_stress=%d stat_interval=%d verbose=%d shuffle_interval=%d stutter=%d shutdown_secs=%d onoff_interval=%d onoff_holdoff=%d\n",
+		 torture_type, tag, cxt.debug_lock ? " [debug]": "",
+		 cxt.nrealwriters_stress, cxt.nrealreaders_stress, stat_interval,
+		 verbose, shuffle_interval, stutter, shutdown_secs,
+		 onoff_interval, onoff_holdoff);
+}
+
+static void lock_torture_cleanup(void)
+{
+	int i;
+
+	if (torture_cleanup_begin())
+		return;
+
+	if (writer_tasks) {
+		for (i = 0; i < cxt.nrealwriters_stress; i++)
+			torture_stop_kthread(lock_torture_writer,
+					     writer_tasks[i]);
+		kfree(writer_tasks);
+		writer_tasks = NULL;
+	}
+
+	if (reader_tasks) {
+		for (i = 0; i < cxt.nrealreaders_stress; i++)
+			torture_stop_kthread(lock_torture_reader,
+					     reader_tasks[i]);
+		kfree(reader_tasks);
+		reader_tasks = NULL;
+	}
+
+	torture_stop_kthread(lock_torture_stats, stats_task);
+	lock_torture_stats_print();  /* -After- the stats thread is stopped! */
+
+	if (atomic_read(&cxt.n_lock_torture_errors))
+		lock_torture_print_module_parms(cxt.cur_ops,
+						"End of test: FAILURE");
+	else if (torture_onoff_failures())
+		lock_torture_print_module_parms(cxt.cur_ops,
+						"End of test: LOCK_HOTPLUG");
+	else
+		lock_torture_print_module_parms(cxt.cur_ops,
+						"End of test: SUCCESS");
+	torture_cleanup_end();
+}
+
+static int __init lock_torture_init(void)
+{
+	int i, j;
+	int firsterr = 0;
+	static struct lock_torture_ops *torture_ops[] = {
+		&lock_busted_ops,
+		&spin_lock_ops, &spin_lock_irq_ops,
+		&rw_lock_ops, &rw_lock_irq_ops,
+		&mutex_lock_ops,
+		&rwsem_lock_ops,
+	};
+
+	if (!torture_init_begin(torture_type, verbose, &torture_runnable))
+		return -EBUSY;
+
+	/* Process args and tell the world that the torturer is on the job. */
+	for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
+		cxt.cur_ops = torture_ops[i];
+		if (strcmp(torture_type, cxt.cur_ops->name) == 0)
+			break;
+	}
+	if (i == ARRAY_SIZE(torture_ops)) {
+		pr_alert("lock-torture: invalid torture type: \"%s\"\n",
+			 torture_type);
+		pr_alert("lock-torture types:");
+		for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
+			pr_alert(" %s", torture_ops[i]->name);
+		pr_alert("\n");
+		torture_init_end();
+		return -EINVAL;
+	}
+	if (cxt.cur_ops->init)
+		cxt.cur_ops->init(); /* no "goto unwind" prior to this point!!! */
+
+	if (nwriters_stress >= 0)
+		cxt.nrealwriters_stress = nwriters_stress;
+	else
+		cxt.nrealwriters_stress = 2 * num_online_cpus();
+
+#ifdef CONFIG_DEBUG_MUTEXES
+	if (strncmp(torture_type, "mutex", 5) == 0)
+		cxt.debug_lock = true;
+#endif
+#ifdef CONFIG_DEBUG_SPINLOCK
+	if ((strncmp(torture_type, "spin", 4) == 0) ||
+	    (strncmp(torture_type, "rw_lock", 7) == 0))
+		cxt.debug_lock = true;
+#endif
+
+	/* Initialize the statistics so that each run gets its own numbers. */
+
+	lock_is_write_held = 0;
+	cxt.lwsa = kmalloc(sizeof(*cxt.lwsa) * cxt.nrealwriters_stress, GFP_KERNEL);
+	if (cxt.lwsa == NULL) {
+		VERBOSE_TOROUT_STRING("cxt.lwsa: Out of memory");
+		firsterr = -ENOMEM;
+		goto unwind;
+	}
+	for (i = 0; i < cxt.nrealwriters_stress; i++) {
+		cxt.lwsa[i].n_lock_fail = 0;
+		cxt.lwsa[i].n_lock_acquired = 0;
+	}
+
+	if (cxt.cur_ops->readlock) {
+		if (nreaders_stress >= 0)
+			cxt.nrealreaders_stress = nreaders_stress;
+		else {
+			/*
+			 * By default distribute evenly the number of
+			 * readers and writers. We still run the same number
+			 * of threads as the writer-only locks default.
+			 */
+			if (nwriters_stress < 0) /* user doesn't care */
+				cxt.nrealwriters_stress = num_online_cpus();
+			cxt.nrealreaders_stress = cxt.nrealwriters_stress;
+		}
+
+		lock_is_read_held = 0;
+		cxt.lrsa = kmalloc(sizeof(*cxt.lrsa) * cxt.nrealreaders_stress, GFP_KERNEL);
+		if (cxt.lrsa == NULL) {
+			VERBOSE_TOROUT_STRING("cxt.lrsa: Out of memory");
+			firsterr = -ENOMEM;
+			kfree(cxt.lwsa);
+			goto unwind;
+		}
+
+		for (i = 0; i < cxt.nrealreaders_stress; i++) {
+			cxt.lrsa[i].n_lock_fail = 0;
+			cxt.lrsa[i].n_lock_acquired = 0;
+		}
+	}
+	lock_torture_print_module_parms(cxt.cur_ops, "Start of test");
+
+	/* Prepare torture context. */
+	if (onoff_interval > 0) {
+		firsterr = torture_onoff_init(onoff_holdoff * HZ,
+					      onoff_interval * HZ);
+		if (firsterr)
+			goto unwind;
+	}
+	if (shuffle_interval > 0) {
+		firsterr = torture_shuffle_init(shuffle_interval);
+		if (firsterr)
+			goto unwind;
+	}
+	if (shutdown_secs > 0) {
+		firsterr = torture_shutdown_init(shutdown_secs,
+						 lock_torture_cleanup);
+		if (firsterr)
+			goto unwind;
+	}
+	if (stutter > 0) {
+		firsterr = torture_stutter_init(stutter);
+		if (firsterr)
+			goto unwind;
+	}
+
+	writer_tasks = kzalloc(cxt.nrealwriters_stress * sizeof(writer_tasks[0]),
+			       GFP_KERNEL);
+	if (writer_tasks == NULL) {
+		VERBOSE_TOROUT_ERRSTRING("writer_tasks: Out of memory");
+		firsterr = -ENOMEM;
+		goto unwind;
+	}
+
+	if (cxt.cur_ops->readlock) {
+		reader_tasks = kzalloc(cxt.nrealreaders_stress * sizeof(reader_tasks[0]),
+				       GFP_KERNEL);
+		if (reader_tasks == NULL) {
+			VERBOSE_TOROUT_ERRSTRING("reader_tasks: Out of memory");
+			firsterr = -ENOMEM;
+			goto unwind;
+		}
+	}
+
+	/*
+	 * Create the kthreads and start torturing (oh, those poor little locks).
+	 *
+	 * TODO: Note that we interleave writers with readers, giving writers a
+	 * slight advantage, by creating its kthread first. This can be modified
+	 * for very specific needs, or even let the user choose the policy, if
+	 * ever wanted.
+	 */
+	for (i = 0, j = 0; i < cxt.nrealwriters_stress ||
+		    j < cxt.nrealreaders_stress; i++, j++) {
+		if (i >= cxt.nrealwriters_stress)
+			goto create_reader;
+
+		/* Create writer. */
+		firsterr = torture_create_kthread(lock_torture_writer, &cxt.lwsa[i],
+						  writer_tasks[i]);
+		if (firsterr)
+			goto unwind;
+
+	create_reader:
+		if (cxt.cur_ops->readlock == NULL || (j >= cxt.nrealreaders_stress))
+			continue;
+		/* Create reader. */
+		firsterr = torture_create_kthread(lock_torture_reader, &cxt.lrsa[j],
+						  reader_tasks[j]);
+		if (firsterr)
+			goto unwind;
+	}
+	if (stat_interval > 0) {
+		firsterr = torture_create_kthread(lock_torture_stats, NULL,
+						  stats_task);
+		if (firsterr)
+			goto unwind;
+	}
+	torture_init_end();
+	return 0;
+
+unwind:
+	torture_init_end();
+	lock_torture_cleanup();
+	return firsterr;
+}
+
+module_init(lock_torture_init);
+module_exit(lock_torture_cleanup);
diff --git a/kernel/locking/mcs_spinlock.h b/kernel/locking/mcs_spinlock.h
new file mode 100644
index 000000000..75e114bdf
--- /dev/null
+++ b/kernel/locking/mcs_spinlock.h
@@ -0,0 +1,111 @@
+/*
+ * MCS lock defines
+ *
+ * This file contains the main data structure and API definitions of MCS lock.
+ *
+ * The MCS lock (proposed by Mellor-Crummey and Scott) is a simple spin-lock
+ * with the desirable properties of being fair, and with each cpu trying
+ * to acquire the lock spinning on a local variable.
+ * It avoids expensive cache bouncings that common test-and-set spin-lock
+ * implementations incur.
+ */
+#ifndef __LINUX_MCS_SPINLOCK_H
+#define __LINUX_MCS_SPINLOCK_H
+
+#include <asm/mcs_spinlock.h>
+
+struct mcs_spinlock {
+	struct mcs_spinlock *next;
+	int locked; /* 1 if lock acquired */
+};
+
+#ifndef arch_mcs_spin_lock_contended
+/*
+ * Using smp_load_acquire() provides a memory barrier that ensures
+ * subsequent operations happen after the lock is acquired.
+ */
+#define arch_mcs_spin_lock_contended(l)					\
+do {									\
+	while (!(smp_load_acquire(l)))					\
+		cpu_relax_lowlatency();					\
+} while (0)
+#endif
+
+#ifndef arch_mcs_spin_unlock_contended
+/*
+ * smp_store_release() provides a memory barrier to ensure all
+ * operations in the critical section has been completed before
+ * unlocking.
+ */
+#define arch_mcs_spin_unlock_contended(l)				\
+	smp_store_release((l), 1)
+#endif
+
+/*
+ * Note: the smp_load_acquire/smp_store_release pair is not
+ * sufficient to form a full memory barrier across
+ * cpus for many architectures (except x86) for mcs_unlock and mcs_lock.
+ * For applications that need a full barrier across multiple cpus
+ * with mcs_unlock and mcs_lock pair, smp_mb__after_unlock_lock() should be
+ * used after mcs_lock.
+ */
+
+/*
+ * In order to acquire the lock, the caller should declare a local node and
+ * pass a reference of the node to this function in addition to the lock.
+ * If the lock has already been acquired, then this will proceed to spin
+ * on this node->locked until the previous lock holder sets the node->locked
+ * in mcs_spin_unlock().
+ */
+static inline
+void mcs_spin_lock(struct mcs_spinlock **lock, struct mcs_spinlock *node)
+{
+	struct mcs_spinlock *prev;
+
+	/* Init node */
+	node->locked = 0;
+	node->next   = NULL;
+
+	prev = xchg(lock, node);
+	if (likely(prev == NULL)) {
+		/*
+		 * Lock acquired, don't need to set node->locked to 1. Threads
+		 * only spin on its own node->locked value for lock acquisition.
+		 * However, since this thread can immediately acquire the lock
+		 * and does not proceed to spin on its own node->locked, this
+		 * value won't be used. If a debug mode is needed to
+		 * audit lock status, then set node->locked value here.
+		 */
+		return;
+	}
+	WRITE_ONCE(prev->next, node);
+
+	/* Wait until the lock holder passes the lock down. */
+	arch_mcs_spin_lock_contended(&node->locked);
+}
+
+/*
+ * Releases the lock. The caller should pass in the corresponding node that
+ * was used to acquire the lock.
+ */
+static inline
+void mcs_spin_unlock(struct mcs_spinlock **lock, struct mcs_spinlock *node)
+{
+	struct mcs_spinlock *next = READ_ONCE(node->next);
+
+	if (likely(!next)) {
+		/*
+		 * Release the lock by setting it to NULL
+		 */
+		if (likely(cmpxchg(lock, node, NULL) == node))
+			return;
+		/* Wait until the next pointer is set */
+		while (!(next = READ_ONCE(node->next)))
+			cpu_relax_lowlatency();
+	}
+
+	/* Pass lock to next waiter. */
+	arch_mcs_spin_unlock_contended(&next->locked);
+}
+
+#endif /* __LINUX_MCS_SPINLOCK_H */
diff --git a/kernel/locking/mutex-debug.c b/kernel/locking/mutex-debug.c
new file mode 100644
index 000000000..3ef373600
--- /dev/null
+++ b/kernel/locking/mutex-debug.c
@@ -0,0 +1,120 @@
+/*
+ * kernel/mutex-debug.c
+ *
+ * Debugging code for mutexes
+ *
+ * Started by Ingo Molnar:
+ *
+ *  Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *
+ * lock debugging, locking tree, deadlock detection started by:
+ *
+ *  Copyright (C) 2004, LynuxWorks, Inc., Igor Manyilov, Bill Huey
+ *  Released under the General Public License (GPL).
+ */
+#include <linux/mutex.h>
+#include <linux/delay.h>
+#include <linux/export.h>
+#include <linux/poison.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+#include <linux/kallsyms.h>
+#include <linux/interrupt.h>
+#include <linux/debug_locks.h>
+
+#include "mutex-debug.h"
+
+/*
+ * Must be called with lock->wait_lock held.
+ */
+void debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter)
+{
+	memset(waiter, MUTEX_DEBUG_INIT, sizeof(*waiter));
+	waiter->magic = waiter;
+	INIT_LIST_HEAD(&waiter->list);
+}
+
+void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter)
+{
+	SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
+	DEBUG_LOCKS_WARN_ON(list_empty(&lock->wait_list));
+	DEBUG_LOCKS_WARN_ON(waiter->magic != waiter);
+	DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
+}
+
+void debug_mutex_free_waiter(struct mutex_waiter *waiter)
+{
+	DEBUG_LOCKS_WARN_ON(!list_empty(&waiter->list));
+	memset(waiter, MUTEX_DEBUG_FREE, sizeof(*waiter));
+}
+
+void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,
+			    struct thread_info *ti)
+{
+	SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
+
+	/* Mark the current thread as blocked on the lock: */
+	ti->task->blocked_on = waiter;
+}
+
+void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
+			 struct thread_info *ti)
+{
+	DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
+	DEBUG_LOCKS_WARN_ON(waiter->task != ti->task);
+	DEBUG_LOCKS_WARN_ON(ti->task->blocked_on != waiter);
+	ti->task->blocked_on = NULL;
+
+	list_del_init(&waiter->list);
+	waiter->task = NULL;
+}
+
+void debug_mutex_unlock(struct mutex *lock)
+{
+	if (likely(debug_locks)) {
+		DEBUG_LOCKS_WARN_ON(lock->magic != lock);
+
+		if (!lock->owner)
+			DEBUG_LOCKS_WARN_ON(!lock->owner);
+		else
+			DEBUG_LOCKS_WARN_ON(lock->owner != current);
+
+		DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
+	}
+
+	/*
+	 * __mutex_slowpath_needs_to_unlock() is explicitly 0 for debug
+	 * mutexes so that we can do it here after we've verified state.
+	 */
+	mutex_clear_owner(lock);
+	atomic_set(&lock->count, 1);
+}
+
+void debug_mutex_init(struct mutex *lock, const char *name,
+		      struct lock_class_key *key)
+{
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	/*
+	 * Make sure we are not reinitializing a held lock:
+	 */
+	debug_check_no_locks_freed((void *)lock, sizeof(*lock));
+	lockdep_init_map(&lock->dep_map, name, key, 0);
+#endif
+	lock->magic = lock;
+}
+
+/***
+ * mutex_destroy - mark a mutex unusable
+ * @lock: the mutex to be destroyed
+ *
+ * This function marks the mutex uninitialized, and any subsequent
+ * use of the mutex is forbidden. The mutex must not be locked when
+ * this function is called.
+ */
+void mutex_destroy(struct mutex *lock)
+{
+	DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));
+	lock->magic = NULL;
+}
+
+EXPORT_SYMBOL_GPL(mutex_destroy);
diff --git a/kernel/locking/mutex-debug.h b/kernel/locking/mutex-debug.h
new file mode 100644
index 000000000..0799fd3e4
--- /dev/null
+++ b/kernel/locking/mutex-debug.h
@@ -0,0 +1,55 @@
+/*
+ * Mutexes: blocking mutual exclusion locks
+ *
+ * started by Ingo Molnar:
+ *
+ *  Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *
+ * This file contains mutex debugging related internal declarations,
+ * prototypes and inline functions, for the CONFIG_DEBUG_MUTEXES case.
+ * More details are in kernel/mutex-debug.c.
+ */
+
+/*
+ * This must be called with lock->wait_lock held.
+ */
+extern void debug_mutex_lock_common(struct mutex *lock,
+				    struct mutex_waiter *waiter);
+extern void debug_mutex_wake_waiter(struct mutex *lock,
+				    struct mutex_waiter *waiter);
+extern void debug_mutex_free_waiter(struct mutex_waiter *waiter);
+extern void debug_mutex_add_waiter(struct mutex *lock,
+				   struct mutex_waiter *waiter,
+				   struct thread_info *ti);
+extern void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
+				struct thread_info *ti);
+extern void debug_mutex_unlock(struct mutex *lock);
+extern void debug_mutex_init(struct mutex *lock, const char *name,
+			     struct lock_class_key *key);
+
+static inline void mutex_set_owner(struct mutex *lock)
+{
+	lock->owner = current;
+}
+
+static inline void mutex_clear_owner(struct mutex *lock)
+{
+	lock->owner = NULL;
+}
+
+#define spin_lock_mutex(lock, flags)			\
+	do {						\
+		struct mutex *l = container_of(lock, struct mutex, wait_lock); \
+							\
+		DEBUG_LOCKS_WARN_ON(in_interrupt());	\
+		local_irq_save(flags);			\
+		arch_spin_lock(&(lock)->rlock.raw_lock);\
+		DEBUG_LOCKS_WARN_ON(l->magic != l);	\
+	} while (0)
+
+#define spin_unlock_mutex(lock, flags)				\
+	do {							\
+		arch_spin_unlock(&(lock)->rlock.raw_lock);	\
+		local_irq_restore(flags);			\
+		preempt_check_resched();			\
+	} while (0)
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
new file mode 100644
index 000000000..4cccea6b8
--- /dev/null
+++ b/kernel/locking/mutex.c
@@ -0,0 +1,972 @@
+/*
+ * kernel/locking/mutex.c
+ *
+ * Mutexes: blocking mutual exclusion locks
+ *
+ * Started by Ingo Molnar:
+ *
+ *  Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *
+ * Many thanks to Arjan van de Ven, Thomas Gleixner, Steven Rostedt and
+ * David Howells for suggestions and improvements.
+ *
+ *  - Adaptive spinning for mutexes by Peter Zijlstra. (Ported to mainline
+ *    from the -rt tree, where it was originally implemented for rtmutexes
+ *    by Steven Rostedt, based on work by Gregory Haskins, Peter Morreale
+ *    and Sven Dietrich.
+ *
+ * Also see Documentation/locking/mutex-design.txt.
+ */
+#include <linux/mutex.h>
+#include <linux/ww_mutex.h>
+#include <linux/sched.h>
+#include <linux/sched/rt.h>
+#include <linux/export.h>
+#include <linux/spinlock.h>
+#include <linux/interrupt.h>
+#include <linux/debug_locks.h>
+#include <linux/osq_lock.h>
+
+/*
+ * In the DEBUG case we are using the "NULL fastpath" for mutexes,
+ * which forces all calls into the slowpath:
+ */
+#ifdef CONFIG_DEBUG_MUTEXES
+# include "mutex-debug.h"
+# include <asm-generic/mutex-null.h>
+/*
+ * Must be 0 for the debug case so we do not do the unlock outside of the
+ * wait_lock region. debug_mutex_unlock() will do the actual unlock in this
+ * case.
+ */
+# undef __mutex_slowpath_needs_to_unlock
+# define  __mutex_slowpath_needs_to_unlock()	0
+#else
+# include "mutex.h"
+# include <asm/mutex.h>
+#endif
+
+void
+__mutex_init(struct mutex *lock, const char *name, struct lock_class_key *key)
+{
+	atomic_set(&lock->count, 1);
+	spin_lock_init(&lock->wait_lock);
+	INIT_LIST_HEAD(&lock->wait_list);
+	mutex_clear_owner(lock);
+#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
+	osq_lock_init(&lock->osq);
+#endif
+
+	debug_mutex_init(lock, name, key);
+}
+
+EXPORT_SYMBOL(__mutex_init);
+
+#ifndef CONFIG_DEBUG_LOCK_ALLOC
+/*
+ * We split the mutex lock/unlock logic into separate fastpath and
+ * slowpath functions, to reduce the register pressure on the fastpath.
+ * We also put the fastpath first in the kernel image, to make sure the
+ * branch is predicted by the CPU as default-untaken.
+ */
+__visible void __sched __mutex_lock_slowpath(atomic_t *lock_count);
+
+/**
+ * mutex_lock - acquire the mutex
+ * @lock: the mutex to be acquired
+ *
+ * Lock the mutex exclusively for this task. If the mutex is not
+ * available right now, it will sleep until it can get it.
+ *
+ * The mutex must later on be released by the same task that
+ * acquired it. Recursive locking is not allowed. The task
+ * may not exit without first unlocking the mutex. Also, kernel
+ * memory where the mutex resides must not be freed with
+ * the mutex still locked. The mutex must first be initialized
+ * (or statically defined) before it can be locked. memset()-ing
+ * the mutex to 0 is not allowed.
+ *
+ * ( The CONFIG_DEBUG_MUTEXES .config option turns on debugging
+ *   checks that will enforce the restrictions and will also do
+ *   deadlock debugging. )
+ *
+ * This function is similar to (but not equivalent to) down().
+ */
+void __sched mutex_lock(struct mutex *lock)
+{
+	might_sleep();
+	/*
+	 * The locking fastpath is the 1->0 transition from
+	 * 'unlocked' into 'locked' state.
+	 */
+	__mutex_fastpath_lock(&lock->count, __mutex_lock_slowpath);
+	mutex_set_owner(lock);
+}
+
+EXPORT_SYMBOL(mutex_lock);
+#endif
+
+static __always_inline void ww_mutex_lock_acquired(struct ww_mutex *ww,
+						   struct ww_acquire_ctx *ww_ctx)
+{
+#ifdef CONFIG_DEBUG_MUTEXES
+	/*
+	 * If this WARN_ON triggers, you used ww_mutex_lock to acquire,
+	 * but released with a normal mutex_unlock in this call.
+	 *
+	 * This should never happen, always use ww_mutex_unlock.
+	 */
+	DEBUG_LOCKS_WARN_ON(ww->ctx);
+
+	/*
+	 * Not quite done after calling ww_acquire_done() ?
+	 */
+	DEBUG_LOCKS_WARN_ON(ww_ctx->done_acquire);
+
+	if (ww_ctx->contending_lock) {
+		/*
+		 * After -EDEADLK you tried to
+		 * acquire a different ww_mutex? Bad!
+		 */
+		DEBUG_LOCKS_WARN_ON(ww_ctx->contending_lock != ww);
+
+		/*
+		 * You called ww_mutex_lock after receiving -EDEADLK,
+		 * but 'forgot' to unlock everything else first?
+		 */
+		DEBUG_LOCKS_WARN_ON(ww_ctx->acquired > 0);
+		ww_ctx->contending_lock = NULL;
+	}
+
+	/*
+	 * Naughty, using a different class will lead to undefined behavior!
+	 */
+	DEBUG_LOCKS_WARN_ON(ww_ctx->ww_class != ww->ww_class);
+#endif
+	ww_ctx->acquired++;
+}
+
+/*
+ * After acquiring lock with fastpath or when we lost out in contested
+ * slowpath, set ctx and wake up any waiters so they can recheck.
+ *
+ * This function is never called when CONFIG_DEBUG_LOCK_ALLOC is set,
+ * as the fastpath and opportunistic spinning are disabled in that case.
+ */
+static __always_inline void
+ww_mutex_set_context_fastpath(struct ww_mutex *lock,
+			       struct ww_acquire_ctx *ctx)
+{
+	unsigned long flags;
+	struct mutex_waiter *cur;
+
+	ww_mutex_lock_acquired(lock, ctx);
+
+	lock->ctx = ctx;
+
+	/*
+	 * The lock->ctx update should be visible on all cores before
+	 * the atomic read is done, otherwise contended waiters might be
+	 * missed. The contended waiters will either see ww_ctx == NULL
+	 * and keep spinning, or it will acquire wait_lock, add itself
+	 * to waiter list and sleep.
+	 */
+	smp_mb(); /* ^^^ */
+
+	/*
+	 * Check if lock is contended, if not there is nobody to wake up
+	 */
+	if (likely(atomic_read(&lock->base.count) == 0))
+		return;
+
+	/*
+	 * Uh oh, we raced in fastpath, wake up everyone in this case,
+	 * so they can see the new lock->ctx.
+	 */
+	spin_lock_mutex(&lock->base.wait_lock, flags);
+	list_for_each_entry(cur, &lock->base.wait_list, list) {
+		debug_mutex_wake_waiter(&lock->base, cur);
+		wake_up_process(cur->task);
+	}
+	spin_unlock_mutex(&lock->base.wait_lock, flags);
+}
+
+/*
+ * After acquiring lock in the slowpath set ctx and wake up any
+ * waiters so they can recheck.
+ *
+ * Callers must hold the mutex wait_lock.
+ */
+static __always_inline void
+ww_mutex_set_context_slowpath(struct ww_mutex *lock,
+			      struct ww_acquire_ctx *ctx)
+{
+	struct mutex_waiter *cur;
+
+	ww_mutex_lock_acquired(lock, ctx);
+	lock->ctx = ctx;
+
+	/*
+	 * Give any possible sleeping processes the chance to wake up,
+	 * so they can recheck if they have to back off.
+	 */
+	list_for_each_entry(cur, &lock->base.wait_list, list) {
+		debug_mutex_wake_waiter(&lock->base, cur);
+		wake_up_process(cur->task);
+	}
+}
+
+#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
+/*
+ * Look out! "owner" is an entirely speculative pointer
+ * access and not reliable.
+ */
+static noinline
+bool mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner)
+{
+	bool ret = true;
+
+	rcu_read_lock();
+	while (lock->owner == owner) {
+		/*
+		 * Ensure we emit the owner->on_cpu, dereference _after_
+		 * checking lock->owner still matches owner. If that fails,
+		 * owner might point to freed memory. If it still matches,
+		 * the rcu_read_lock() ensures the memory stays valid.
+		 */
+		barrier();
+
+		if (!owner->on_cpu || need_resched()) {
+			ret = false;
+			break;
+		}
+
+		cpu_relax_lowlatency();
+	}
+	rcu_read_unlock();
+
+	return ret;
+}
+
+/*
+ * Initial check for entering the mutex spinning loop
+ */
+static inline int mutex_can_spin_on_owner(struct mutex *lock)
+{
+	struct task_struct *owner;
+	int retval = 1;
+
+	if (need_resched())
+		return 0;
+
+	rcu_read_lock();
+	owner = READ_ONCE(lock->owner);
+	if (owner)
+		retval = owner->on_cpu;
+	rcu_read_unlock();
+	/*
+	 * if lock->owner is not set, the mutex owner may have just acquired
+	 * it and not set the owner yet or the mutex has been released.
+	 */
+	return retval;
+}
+
+/*
+ * Atomically try to take the lock when it is available
+ */
+static inline bool mutex_try_to_acquire(struct mutex *lock)
+{
+	return !mutex_is_locked(lock) &&
+		(atomic_cmpxchg(&lock->count, 1, 0) == 1);
+}
+
+/*
+ * Optimistic spinning.
+ *
+ * We try to spin for acquisition when we find that the lock owner
+ * is currently running on a (different) CPU and while we don't
+ * need to reschedule. The rationale is that if the lock owner is
+ * running, it is likely to release the lock soon.
+ *
+ * Since this needs the lock owner, and this mutex implementation
+ * doesn't track the owner atomically in the lock field, we need to
+ * track it non-atomically.
+ *
+ * We can't do this for DEBUG_MUTEXES because that relies on wait_lock
+ * to serialize everything.
+ *
+ * The mutex spinners are queued up using MCS lock so that only one
+ * spinner can compete for the mutex. However, if mutex spinning isn't
+ * going to happen, there is no point in going through the lock/unlock
+ * overhead.
+ *
+ * Returns true when the lock was taken, otherwise false, indicating
+ * that we need to jump to the slowpath and sleep.
+ */
+static bool mutex_optimistic_spin(struct mutex *lock,
+				  struct ww_acquire_ctx *ww_ctx, const bool use_ww_ctx)
+{
+	struct task_struct *task = current;
+
+	if (!mutex_can_spin_on_owner(lock))
+		goto done;
+
+	/*
+	 * In order to avoid a stampede of mutex spinners trying to
+	 * acquire the mutex all at once, the spinners need to take a
+	 * MCS (queued) lock first before spinning on the owner field.
+	 */
+	if (!osq_lock(&lock->osq))
+		goto done;
+
+	while (true) {
+		struct task_struct *owner;
+
+		if (use_ww_ctx && ww_ctx->acquired > 0) {
+			struct ww_mutex *ww;
+
+			ww = container_of(lock, struct ww_mutex, base);
+			/*
+			 * If ww->ctx is set the contents are undefined, only
+			 * by acquiring wait_lock there is a guarantee that
+			 * they are not invalid when reading.
+			 *
+			 * As such, when deadlock detection needs to be
+			 * performed the optimistic spinning cannot be done.
+			 */
+			if (READ_ONCE(ww->ctx))
+				break;
+		}
+
+		/*
+		 * If there's an owner, wait for it to either
+		 * release the lock or go to sleep.
+		 */
+		owner = READ_ONCE(lock->owner);
+		if (owner && !mutex_spin_on_owner(lock, owner))
+			break;
+
+		/* Try to acquire the mutex if it is unlocked. */
+		if (mutex_try_to_acquire(lock)) {
+			lock_acquired(&lock->dep_map, ip);
+
+			if (use_ww_ctx) {
+				struct ww_mutex *ww;
+				ww = container_of(lock, struct ww_mutex, base);
+
+				ww_mutex_set_context_fastpath(ww, ww_ctx);
+			}
+
+			mutex_set_owner(lock);
+			osq_unlock(&lock->osq);
+			return true;
+		}
+
+		/*
+		 * When there's no owner, we might have preempted between the
+		 * owner acquiring the lock and setting the owner field. If
+		 * we're an RT task that will live-lock because we won't let
+		 * the owner complete.
+		 */
+		if (!owner && (need_resched() || rt_task(task)))
+			break;
+
+		/*
+		 * The cpu_relax() call is a compiler barrier which forces
+		 * everything in this loop to be re-loaded. We don't need
+		 * memory barriers as we'll eventually observe the right
+		 * values at the cost of a few extra spins.
+		 */
+		cpu_relax_lowlatency();
+	}
+
+	osq_unlock(&lock->osq);
+done:
+	/*
+	 * If we fell out of the spin path because of need_resched(),
+	 * reschedule now, before we try-lock the mutex. This avoids getting
+	 * scheduled out right after we obtained the mutex.
+	 */
+	if (need_resched()) {
+		/*
+		 * We _should_ have TASK_RUNNING here, but just in case
+		 * we do not, make it so, otherwise we might get stuck.
+		 */
+		__set_current_state(TASK_RUNNING);
+		schedule_preempt_disabled();
+	}
+
+	return false;
+}
+#else
+static bool mutex_optimistic_spin(struct mutex *lock,
+				  struct ww_acquire_ctx *ww_ctx, const bool use_ww_ctx)
+{
+	return false;
+}
+#endif
+
+__visible __used noinline
+void __sched __mutex_unlock_slowpath(atomic_t *lock_count);
+
+/**
+ * mutex_unlock - release the mutex
+ * @lock: the mutex to be released
+ *
+ * Unlock a mutex that has been locked by this task previously.
+ *
+ * This function must not be used in interrupt context. Unlocking
+ * of a not locked mutex is not allowed.
+ *
+ * This function is similar to (but not equivalent to) up().
+ */
+void __sched mutex_unlock(struct mutex *lock)
+{
+	/*
+	 * The unlocking fastpath is the 0->1 transition from 'locked'
+	 * into 'unlocked' state:
+	 */
+#ifndef CONFIG_DEBUG_MUTEXES
+	/*
+	 * When debugging is enabled we must not clear the owner before time,
+	 * the slow path will always be taken, and that clears the owner field
+	 * after verifying that it was indeed current.
+	 */
+	mutex_clear_owner(lock);
+#endif
+	__mutex_fastpath_unlock(&lock->count, __mutex_unlock_slowpath);
+}
+
+EXPORT_SYMBOL(mutex_unlock);
+
+/**
+ * ww_mutex_unlock - release the w/w mutex
+ * @lock: the mutex to be released
+ *
+ * Unlock a mutex that has been locked by this task previously with any of the
+ * ww_mutex_lock* functions (with or without an acquire context). It is
+ * forbidden to release the locks after releasing the acquire context.
+ *
+ * This function must not be used in interrupt context. Unlocking
+ * of a unlocked mutex is not allowed.
+ */
+void __sched ww_mutex_unlock(struct ww_mutex *lock)
+{
+	/*
+	 * The unlocking fastpath is the 0->1 transition from 'locked'
+	 * into 'unlocked' state:
+	 */
+	if (lock->ctx) {
+#ifdef CONFIG_DEBUG_MUTEXES
+		DEBUG_LOCKS_WARN_ON(!lock->ctx->acquired);
+#endif
+		if (lock->ctx->acquired > 0)
+			lock->ctx->acquired--;
+		lock->ctx = NULL;
+	}
+
+#ifndef CONFIG_DEBUG_MUTEXES
+	/*
+	 * When debugging is enabled we must not clear the owner before time,
+	 * the slow path will always be taken, and that clears the owner field
+	 * after verifying that it was indeed current.
+	 */
+	mutex_clear_owner(&lock->base);
+#endif
+	__mutex_fastpath_unlock(&lock->base.count, __mutex_unlock_slowpath);
+}
+EXPORT_SYMBOL(ww_mutex_unlock);
+
+static inline int __sched
+__ww_mutex_lock_check_stamp(struct mutex *lock, struct ww_acquire_ctx *ctx)
+{
+	struct ww_mutex *ww = container_of(lock, struct ww_mutex, base);
+	struct ww_acquire_ctx *hold_ctx = READ_ONCE(ww->ctx);
+
+	if (!hold_ctx)
+		return 0;
+
+	if (unlikely(ctx == hold_ctx))
+		return -EALREADY;
+
+	if (ctx->stamp - hold_ctx->stamp <= LONG_MAX &&
+	    (ctx->stamp != hold_ctx->stamp || ctx > hold_ctx)) {
+#ifdef CONFIG_DEBUG_MUTEXES
+		DEBUG_LOCKS_WARN_ON(ctx->contending_lock);
+		ctx->contending_lock = ww;
+#endif
+		return -EDEADLK;
+	}
+
+	return 0;
+}
+
+/*
+ * Lock a mutex (possibly interruptible), slowpath:
+ */
+static __always_inline int __sched
+__mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
+		    struct lockdep_map *nest_lock, unsigned long ip,
+		    struct ww_acquire_ctx *ww_ctx, const bool use_ww_ctx)
+{
+	struct task_struct *task = current;
+	struct mutex_waiter waiter;
+	unsigned long flags;
+	int ret;
+
+	preempt_disable();
+	mutex_acquire_nest(&lock->dep_map, subclass, 0, nest_lock, ip);
+
+	if (mutex_optimistic_spin(lock, ww_ctx, use_ww_ctx)) {
+		/* got the lock, yay! */
+		preempt_enable();
+		return 0;
+	}
+
+	spin_lock_mutex(&lock->wait_lock, flags);
+
+	/*
+	 * Once more, try to acquire the lock. Only try-lock the mutex if
+	 * it is unlocked to reduce unnecessary xchg() operations.
+	 */
+	if (!mutex_is_locked(lock) && (atomic_xchg(&lock->count, 0) == 1))
+		goto skip_wait;
+
+	debug_mutex_lock_common(lock, &waiter);
+	debug_mutex_add_waiter(lock, &waiter, task_thread_info(task));
+
+	/* add waiting tasks to the end of the waitqueue (FIFO): */
+	list_add_tail(&waiter.list, &lock->wait_list);
+	waiter.task = task;
+
+	lock_contended(&lock->dep_map, ip);
+
+	for (;;) {
+		/*
+		 * Lets try to take the lock again - this is needed even if
+		 * we get here for the first time (shortly after failing to
+		 * acquire the lock), to make sure that we get a wakeup once
+		 * it's unlocked. Later on, if we sleep, this is the
+		 * operation that gives us the lock. We xchg it to -1, so
+		 * that when we release the lock, we properly wake up the
+		 * other waiters. We only attempt the xchg if the count is
+		 * non-negative in order to avoid unnecessary xchg operations:
+		 */
+		if (atomic_read(&lock->count) >= 0 &&
+		    (atomic_xchg(&lock->count, -1) == 1))
+			break;
+
+		/*
+		 * got a signal? (This code gets eliminated in the
+		 * TASK_UNINTERRUPTIBLE case.)
+		 */
+		if (unlikely(signal_pending_state(state, task))) {
+			ret = -EINTR;
+			goto err;
+		}
+
+		if (use_ww_ctx && ww_ctx->acquired > 0) {
+			ret = __ww_mutex_lock_check_stamp(lock, ww_ctx);
+			if (ret)
+				goto err;
+		}
+
+		__set_task_state(task, state);
+
+		/* didn't get the lock, go to sleep: */
+		spin_unlock_mutex(&lock->wait_lock, flags);
+		schedule_preempt_disabled();
+		spin_lock_mutex(&lock->wait_lock, flags);
+	}
+	__set_task_state(task, TASK_RUNNING);
+
+	mutex_remove_waiter(lock, &waiter, current_thread_info());
+	/* set it to 0 if there are no waiters left: */
+	if (likely(list_empty(&lock->wait_list)))
+		atomic_set(&lock->count, 0);
+	debug_mutex_free_waiter(&waiter);
+
+skip_wait:
+	/* got the lock - cleanup and rejoice! */
+	lock_acquired(&lock->dep_map, ip);
+	mutex_set_owner(lock);
+
+	if (use_ww_ctx) {
+		struct ww_mutex *ww = container_of(lock, struct ww_mutex, base);
+		ww_mutex_set_context_slowpath(ww, ww_ctx);
+	}
+
+	spin_unlock_mutex(&lock->wait_lock, flags);
+	preempt_enable();
+	return 0;
+
+err:
+	mutex_remove_waiter(lock, &waiter, task_thread_info(task));
+	spin_unlock_mutex(&lock->wait_lock, flags);
+	debug_mutex_free_waiter(&waiter);
+	mutex_release(&lock->dep_map, 1, ip);
+	preempt_enable();
+	return ret;
+}
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+void __sched
+mutex_lock_nested(struct mutex *lock, unsigned int subclass)
+{
+	might_sleep();
+	__mutex_lock_common(lock, TASK_UNINTERRUPTIBLE,
+			    subclass, NULL, _RET_IP_, NULL, 0);
+}
+
+EXPORT_SYMBOL_GPL(mutex_lock_nested);
+
+void __sched
+_mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest)
+{
+	might_sleep();
+	__mutex_lock_common(lock, TASK_UNINTERRUPTIBLE,
+			    0, nest, _RET_IP_, NULL, 0);
+}
+
+EXPORT_SYMBOL_GPL(_mutex_lock_nest_lock);
+
+int __sched
+mutex_lock_killable_nested(struct mutex *lock, unsigned int subclass)
+{
+	might_sleep();
+	return __mutex_lock_common(lock, TASK_KILLABLE,
+				   subclass, NULL, _RET_IP_, NULL, 0);
+}
+EXPORT_SYMBOL_GPL(mutex_lock_killable_nested);
+
+int __sched
+mutex_lock_interruptible_nested(struct mutex *lock, unsigned int subclass)
+{
+	might_sleep();
+	return __mutex_lock_common(lock, TASK_INTERRUPTIBLE,
+				   subclass, NULL, _RET_IP_, NULL, 0);
+}
+
+EXPORT_SYMBOL_GPL(mutex_lock_interruptible_nested);
+
+static inline int
+ww_mutex_deadlock_injection(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
+{
+#ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH
+	unsigned tmp;
+
+	if (ctx->deadlock_inject_countdown-- == 0) {
+		tmp = ctx->deadlock_inject_interval;
+		if (tmp > UINT_MAX/4)
+			tmp = UINT_MAX;
+		else
+			tmp = tmp*2 + tmp + tmp/2;
+
+		ctx->deadlock_inject_interval = tmp;
+		ctx->deadlock_inject_countdown = tmp;
+		ctx->contending_lock = lock;
+
+		ww_mutex_unlock(lock);
+
+		return -EDEADLK;
+	}
+#endif
+
+	return 0;
+}
+
+int __sched
+__ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
+{
+	int ret;
+
+	might_sleep();
+	ret =  __mutex_lock_common(&lock->base, TASK_UNINTERRUPTIBLE,
+				   0, &ctx->dep_map, _RET_IP_, ctx, 1);
+	if (!ret && ctx->acquired > 1)
+		return ww_mutex_deadlock_injection(lock, ctx);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(__ww_mutex_lock);
+
+int __sched
+__ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
+{
+	int ret;
+
+	might_sleep();
+	ret = __mutex_lock_common(&lock->base, TASK_INTERRUPTIBLE,
+				  0, &ctx->dep_map, _RET_IP_, ctx, 1);
+
+	if (!ret && ctx->acquired > 1)
+		return ww_mutex_deadlock_injection(lock, ctx);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(__ww_mutex_lock_interruptible);
+
+#endif
+
+/*
+ * Release the lock, slowpath:
+ */
+static inline void
+__mutex_unlock_common_slowpath(struct mutex *lock, int nested)
+{
+	unsigned long flags;
+
+	/*
+	 * As a performance measurement, release the lock before doing other
+	 * wakeup related duties to follow. This allows other tasks to acquire
+	 * the lock sooner, while still handling cleanups in past unlock calls.
+	 * This can be done as we do not enforce strict equivalence between the
+	 * mutex counter and wait_list.
+	 *
+	 *
+	 * Some architectures leave the lock unlocked in the fastpath failure
+	 * case, others need to leave it locked. In the later case we have to
+	 * unlock it here - as the lock counter is currently 0 or negative.
+	 */
+	if (__mutex_slowpath_needs_to_unlock())
+		atomic_set(&lock->count, 1);
+
+	spin_lock_mutex(&lock->wait_lock, flags);
+	mutex_release(&lock->dep_map, nested, _RET_IP_);
+	debug_mutex_unlock(lock);
+
+	if (!list_empty(&lock->wait_list)) {
+		/* get the first entry from the wait-list: */
+		struct mutex_waiter *waiter =
+				list_entry(lock->wait_list.next,
+					   struct mutex_waiter, list);
+
+		debug_mutex_wake_waiter(lock, waiter);
+
+		wake_up_process(waiter->task);
+	}
+
+	spin_unlock_mutex(&lock->wait_lock, flags);
+}
+
+/*
+ * Release the lock, slowpath:
+ */
+__visible void
+__mutex_unlock_slowpath(atomic_t *lock_count)
+{
+	struct mutex *lock = container_of(lock_count, struct mutex, count);
+
+	__mutex_unlock_common_slowpath(lock, 1);
+}
+
+#ifndef CONFIG_DEBUG_LOCK_ALLOC
+/*
+ * Here come the less common (and hence less performance-critical) APIs:
+ * mutex_lock_interruptible() and mutex_trylock().
+ */
+static noinline int __sched
+__mutex_lock_killable_slowpath(struct mutex *lock);
+
+static noinline int __sched
+__mutex_lock_interruptible_slowpath(struct mutex *lock);
+
+/**
+ * mutex_lock_interruptible - acquire the mutex, interruptible
+ * @lock: the mutex to be acquired
+ *
+ * Lock the mutex like mutex_lock(), and return 0 if the mutex has
+ * been acquired or sleep until the mutex becomes available. If a
+ * signal arrives while waiting for the lock then this function
+ * returns -EINTR.
+ *
+ * This function is similar to (but not equivalent to) down_interruptible().
+ */
+int __sched mutex_lock_interruptible(struct mutex *lock)
+{
+	int ret;
+
+	might_sleep();
+	ret =  __mutex_fastpath_lock_retval(&lock->count);
+	if (likely(!ret)) {
+		mutex_set_owner(lock);
+		return 0;
+	} else
+		return __mutex_lock_interruptible_slowpath(lock);
+}
+
+EXPORT_SYMBOL(mutex_lock_interruptible);
+
+int __sched mutex_lock_killable(struct mutex *lock)
+{
+	int ret;
+
+	might_sleep();
+	ret = __mutex_fastpath_lock_retval(&lock->count);
+	if (likely(!ret)) {
+		mutex_set_owner(lock);
+		return 0;
+	} else
+		return __mutex_lock_killable_slowpath(lock);
+}
+EXPORT_SYMBOL(mutex_lock_killable);
+
+__visible void __sched
+__mutex_lock_slowpath(atomic_t *lock_count)
+{
+	struct mutex *lock = container_of(lock_count, struct mutex, count);
+
+	__mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0,
+			    NULL, _RET_IP_, NULL, 0);
+}
+
+static noinline int __sched
+__mutex_lock_killable_slowpath(struct mutex *lock)
+{
+	return __mutex_lock_common(lock, TASK_KILLABLE, 0,
+				   NULL, _RET_IP_, NULL, 0);
+}
+
+static noinline int __sched
+__mutex_lock_interruptible_slowpath(struct mutex *lock)
+{
+	return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, 0,
+				   NULL, _RET_IP_, NULL, 0);
+}
+
+static noinline int __sched
+__ww_mutex_lock_slowpath(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
+{
+	return __mutex_lock_common(&lock->base, TASK_UNINTERRUPTIBLE, 0,
+				   NULL, _RET_IP_, ctx, 1);
+}
+
+static noinline int __sched
+__ww_mutex_lock_interruptible_slowpath(struct ww_mutex *lock,
+					    struct ww_acquire_ctx *ctx)
+{
+	return __mutex_lock_common(&lock->base, TASK_INTERRUPTIBLE, 0,
+				   NULL, _RET_IP_, ctx, 1);
+}
+
+#endif
+
+/*
+ * Spinlock based trylock, we take the spinlock and check whether we
+ * can get the lock:
+ */
+static inline int __mutex_trylock_slowpath(atomic_t *lock_count)
+{
+	struct mutex *lock = container_of(lock_count, struct mutex, count);
+	unsigned long flags;
+	int prev;
+
+	/* No need to trylock if the mutex is locked. */
+	if (mutex_is_locked(lock))
+		return 0;
+
+	spin_lock_mutex(&lock->wait_lock, flags);
+
+	prev = atomic_xchg(&lock->count, -1);
+	if (likely(prev == 1)) {
+		mutex_set_owner(lock);
+		mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_);
+	}
+
+	/* Set it back to 0 if there are no waiters: */
+	if (likely(list_empty(&lock->wait_list)))
+		atomic_set(&lock->count, 0);
+
+	spin_unlock_mutex(&lock->wait_lock, flags);
+
+	return prev == 1;
+}
+
+/**
+ * mutex_trylock - try to acquire the mutex, without waiting
+ * @lock: the mutex to be acquired
+ *
+ * Try to acquire the mutex atomically. Returns 1 if the mutex
+ * has been acquired successfully, and 0 on contention.
+ *
+ * NOTE: this function follows the spin_trylock() convention, so
+ * it is negated from the down_trylock() return values! Be careful
+ * about this when converting semaphore users to mutexes.
+ *
+ * This function must not be used in interrupt context. The
+ * mutex must be released by the same task that acquired it.
+ */
+int __sched mutex_trylock(struct mutex *lock)
+{
+	int ret;
+
+	ret = __mutex_fastpath_trylock(&lock->count, __mutex_trylock_slowpath);
+	if (ret)
+		mutex_set_owner(lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(mutex_trylock);
+
+#ifndef CONFIG_DEBUG_LOCK_ALLOC
+int __sched
+__ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
+{
+	int ret;
+
+	might_sleep();
+
+	ret = __mutex_fastpath_lock_retval(&lock->base.count);
+
+	if (likely(!ret)) {
+		ww_mutex_set_context_fastpath(lock, ctx);
+		mutex_set_owner(&lock->base);
+	} else
+		ret = __ww_mutex_lock_slowpath(lock, ctx);
+	return ret;
+}
+EXPORT_SYMBOL(__ww_mutex_lock);
+
+int __sched
+__ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
+{
+	int ret;
+
+	might_sleep();
+
+	ret = __mutex_fastpath_lock_retval(&lock->base.count);
+
+	if (likely(!ret)) {
+		ww_mutex_set_context_fastpath(lock, ctx);
+		mutex_set_owner(&lock->base);
+	} else
+		ret = __ww_mutex_lock_interruptible_slowpath(lock, ctx);
+	return ret;
+}
+EXPORT_SYMBOL(__ww_mutex_lock_interruptible);
+
+#endif
+
+/**
+ * atomic_dec_and_mutex_lock - return holding mutex if we dec to 0
+ * @cnt: the atomic which we are to dec
+ * @lock: the mutex to return holding if we dec to 0
+ *
+ * return true and hold lock if we dec to 0, return false otherwise
+ */
+int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock)
+{
+	/* dec if we can't possibly hit 0 */
+	if (atomic_add_unless(cnt, -1, 1))
+		return 0;
+	/* we might hit 0, so take the lock */
+	mutex_lock(lock);
+	if (!atomic_dec_and_test(cnt)) {
+		/* when we actually did the dec, we didn't hit 0 */
+		mutex_unlock(lock);
+		return 0;
+	}
+	/* we hit 0, and we hold the lock */
+	return 1;
+}
+EXPORT_SYMBOL(atomic_dec_and_mutex_lock);
diff --git a/kernel/locking/mutex.h b/kernel/locking/mutex.h
new file mode 100644
index 000000000..5cda39760
--- /dev/null
+++ b/kernel/locking/mutex.h
@@ -0,0 +1,48 @@
+/*
+ * Mutexes: blocking mutual exclusion locks
+ *
+ * started by Ingo Molnar:
+ *
+ *  Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *
+ * This file contains mutex debugging related internal prototypes, for the
+ * !CONFIG_DEBUG_MUTEXES case. Most of them are NOPs:
+ */
+
+#define spin_lock_mutex(lock, flags) \
+		do { spin_lock(lock); (void)(flags); } while (0)
+#define spin_unlock_mutex(lock, flags) \
+		do { spin_unlock(lock); (void)(flags); } while (0)
+#define mutex_remove_waiter(lock, waiter, ti) \
+		__list_del((waiter)->list.prev, (waiter)->list.next)
+
+#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
+static inline void mutex_set_owner(struct mutex *lock)
+{
+	lock->owner = current;
+}
+
+static inline void mutex_clear_owner(struct mutex *lock)
+{
+	lock->owner = NULL;
+}
+#else
+static inline void mutex_set_owner(struct mutex *lock)
+{
+}
+
+static inline void mutex_clear_owner(struct mutex *lock)
+{
+}
+#endif
+
+#define debug_mutex_wake_waiter(lock, waiter)		do { } while (0)
+#define debug_mutex_free_waiter(waiter)			do { } while (0)
+#define debug_mutex_add_waiter(lock, waiter, ti)	do { } while (0)
+#define debug_mutex_unlock(lock)			do { } while (0)
+#define debug_mutex_init(lock, name, key)		do { } while (0)
+
+static inline void
+debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter)
+{
+}
diff --git a/kernel/locking/osq_lock.c b/kernel/locking/osq_lock.c
new file mode 100644
index 000000000..dc85ee23a
--- /dev/null
+++ b/kernel/locking/osq_lock.c
@@ -0,0 +1,203 @@
+#include <linux/percpu.h>
+#include <linux/sched.h>
+#include <linux/osq_lock.h>
+
+/*
+ * An MCS like lock especially tailored for optimistic spinning for sleeping
+ * lock implementations (mutex, rwsem, etc).
+ *
+ * Using a single mcs node per CPU is safe because sleeping locks should not be
+ * called from interrupt context and we have preemption disabled while
+ * spinning.
+ */
+static DEFINE_PER_CPU_SHARED_ALIGNED(struct optimistic_spin_node, osq_node);
+
+/*
+ * We use the value 0 to represent "no CPU", thus the encoded value
+ * will be the CPU number incremented by 1.
+ */
+static inline int encode_cpu(int cpu_nr)
+{
+	return cpu_nr + 1;
+}
+
+static inline struct optimistic_spin_node *decode_cpu(int encoded_cpu_val)
+{
+	int cpu_nr = encoded_cpu_val - 1;
+
+	return per_cpu_ptr(&osq_node, cpu_nr);
+}
+
+/*
+ * Get a stable @node->next pointer, either for unlock() or unqueue() purposes.
+ * Can return NULL in case we were the last queued and we updated @lock instead.
+ */
+static inline struct optimistic_spin_node *
+osq_wait_next(struct optimistic_spin_queue *lock,
+	      struct optimistic_spin_node *node,
+	      struct optimistic_spin_node *prev)
+{
+	struct optimistic_spin_node *next = NULL;
+	int curr = encode_cpu(smp_processor_id());
+	int old;
+
+	/*
+	 * If there is a prev node in queue, then the 'old' value will be
+	 * the prev node's CPU #, else it's set to OSQ_UNLOCKED_VAL since if
+	 * we're currently last in queue, then the queue will then become empty.
+	 */
+	old = prev ? prev->cpu : OSQ_UNLOCKED_VAL;
+
+	for (;;) {
+		if (atomic_read(&lock->tail) == curr &&
+		    atomic_cmpxchg(&lock->tail, curr, old) == curr) {
+			/*
+			 * We were the last queued, we moved @lock back. @prev
+			 * will now observe @lock and will complete its
+			 * unlock()/unqueue().
+			 */
+			break;
+		}
+
+		/*
+		 * We must xchg() the @node->next value, because if we were to
+		 * leave it in, a concurrent unlock()/unqueue() from
+		 * @node->next might complete Step-A and think its @prev is
+		 * still valid.
+		 *
+		 * If the concurrent unlock()/unqueue() wins the race, we'll
+		 * wait for either @lock to point to us, through its Step-B, or
+		 * wait for a new @node->next from its Step-C.
+		 */
+		if (node->next) {
+			next = xchg(&node->next, NULL);
+			if (next)
+				break;
+		}
+
+		cpu_relax_lowlatency();
+	}
+
+	return next;
+}
+
+bool osq_lock(struct optimistic_spin_queue *lock)
+{
+	struct optimistic_spin_node *node = this_cpu_ptr(&osq_node);
+	struct optimistic_spin_node *prev, *next;
+	int curr = encode_cpu(smp_processor_id());
+	int old;
+
+	node->locked = 0;
+	node->next = NULL;
+	node->cpu = curr;
+
+	old = atomic_xchg(&lock->tail, curr);
+	if (old == OSQ_UNLOCKED_VAL)
+		return true;
+
+	prev = decode_cpu(old);
+	node->prev = prev;
+	WRITE_ONCE(prev->next, node);
+
+	/*
+	 * Normally @prev is untouchable after the above store; because at that
+	 * moment unlock can proceed and wipe the node element from stack.
+	 *
+	 * However, since our nodes are static per-cpu storage, we're
+	 * guaranteed their existence -- this allows us to apply
+	 * cmpxchg in an attempt to undo our queueing.
+	 */
+
+	while (!READ_ONCE(node->locked)) {
+		/*
+		 * If we need to reschedule bail... so we can block.
+		 */
+		if (need_resched())
+			goto unqueue;
+
+		cpu_relax_lowlatency();
+	}
+	return true;
+
+unqueue:
+	/*
+	 * Step - A  -- stabilize @prev
+	 *
+	 * Undo our @prev->next assignment; this will make @prev's
+	 * unlock()/unqueue() wait for a next pointer since @lock points to us
+	 * (or later).
+	 */
+
+	for (;;) {
+		if (prev->next == node &&
+		    cmpxchg(&prev->next, node, NULL) == node)
+			break;
+
+		/*
+		 * We can only fail the cmpxchg() racing against an unlock(),
+		 * in which case we should observe @node->locked becomming
+		 * true.
+		 */
+		if (smp_load_acquire(&node->locked))
+			return true;
+
+		cpu_relax_lowlatency();
+
+		/*
+		 * Or we race against a concurrent unqueue()'s step-B, in which
+		 * case its step-C will write us a new @node->prev pointer.
+		 */
+		prev = READ_ONCE(node->prev);
+	}
+
+	/*
+	 * Step - B -- stabilize @next
+	 *
+	 * Similar to unlock(), wait for @node->next or move @lock from @node
+	 * back to @prev.
+	 */
+
+	next = osq_wait_next(lock, node, prev);
+	if (!next)
+		return false;
+
+	/*
+	 * Step - C -- unlink
+	 *
+	 * @prev is stable because its still waiting for a new @prev->next
+	 * pointer, @next is stable because our @node->next pointer is NULL and
+	 * it will wait in Step-A.
+	 */
+
+	WRITE_ONCE(next->prev, prev);
+	WRITE_ONCE(prev->next, next);
+
+	return false;
+}
+
+void osq_unlock(struct optimistic_spin_queue *lock)
+{
+	struct optimistic_spin_node *node, *next;
+	int curr = encode_cpu(smp_processor_id());
+
+	/*
+	 * Fast path for the uncontended case.
+	 */
+	if (likely(atomic_cmpxchg(&lock->tail, curr, OSQ_UNLOCKED_VAL) == curr))
+		return;
+
+	/*
+	 * Second most likely case.
+	 */
+	node = this_cpu_ptr(&osq_node);
+	next = xchg(&node->next, NULL);
+	if (next) {
+		WRITE_ONCE(next->locked, 1);
+		return;
+	}
+
+	next = osq_wait_next(lock, node, NULL);
+	if (next)
+		WRITE_ONCE(next->locked, 1);
+}
diff --git a/kernel/locking/percpu-rwsem.c b/kernel/locking/percpu-rwsem.c
new file mode 100644
index 000000000..652a8ee8e
--- /dev/null
+++ b/kernel/locking/percpu-rwsem.c
@@ -0,0 +1,165 @@
+#include <linux/atomic.h>
+#include <linux/rwsem.h>
+#include <linux/percpu.h>
+#include <linux/wait.h>
+#include <linux/lockdep.h>
+#include <linux/percpu-rwsem.h>
+#include <linux/rcupdate.h>
+#include <linux/sched.h>
+#include <linux/errno.h>
+
+int __percpu_init_rwsem(struct percpu_rw_semaphore *brw,
+			const char *name, struct lock_class_key *rwsem_key)
+{
+	brw->fast_read_ctr = alloc_percpu(int);
+	if (unlikely(!brw->fast_read_ctr))
+		return -ENOMEM;
+
+	/* ->rw_sem represents the whole percpu_rw_semaphore for lockdep */
+	__init_rwsem(&brw->rw_sem, name, rwsem_key);
+	atomic_set(&brw->write_ctr, 0);
+	atomic_set(&brw->slow_read_ctr, 0);
+	init_waitqueue_head(&brw->write_waitq);
+	return 0;
+}
+
+void percpu_free_rwsem(struct percpu_rw_semaphore *brw)
+{
+	free_percpu(brw->fast_read_ctr);
+	brw->fast_read_ctr = NULL; /* catch use after free bugs */
+}
+
+/*
+ * This is the fast-path for down_read/up_read, it only needs to ensure
+ * there is no pending writer (atomic_read(write_ctr) == 0) and inc/dec the
+ * fast per-cpu counter. The writer uses synchronize_sched_expedited() to
+ * serialize with the preempt-disabled section below.
+ *
+ * The nontrivial part is that we should guarantee acquire/release semantics
+ * in case when
+ *
+ *	R_W: down_write() comes after up_read(), the writer should see all
+ *	     changes done by the reader
+ * or
+ *	W_R: down_read() comes after up_write(), the reader should see all
+ *	     changes done by the writer
+ *
+ * If this helper fails the callers rely on the normal rw_semaphore and
+ * atomic_dec_and_test(), so in this case we have the necessary barriers.
+ *
+ * But if it succeeds we do not have any barriers, atomic_read(write_ctr) or
+ * __this_cpu_add() below can be reordered with any LOAD/STORE done by the
+ * reader inside the critical section. See the comments in down_write and
+ * up_write below.
+ */
+static bool update_fast_ctr(struct percpu_rw_semaphore *brw, unsigned int val)
+{
+	bool success = false;
+
+	preempt_disable();
+	if (likely(!atomic_read(&brw->write_ctr))) {
+		__this_cpu_add(*brw->fast_read_ctr, val);
+		success = true;
+	}
+	preempt_enable();
+
+	return success;
+}
+
+/*
+ * Like the normal down_read() this is not recursive, the writer can
+ * come after the first percpu_down_read() and create the deadlock.
+ *
+ * Note: returns with lock_is_held(brw->rw_sem) == T for lockdep,
+ * percpu_up_read() does rwsem_release(). This pairs with the usage
+ * of ->rw_sem in percpu_down/up_write().
+ */
+void percpu_down_read(struct percpu_rw_semaphore *brw)
+{
+	might_sleep();
+	if (likely(update_fast_ctr(brw, +1))) {
+		rwsem_acquire_read(&brw->rw_sem.dep_map, 0, 0, _RET_IP_);
+		return;
+	}
+
+	down_read(&brw->rw_sem);
+	atomic_inc(&brw->slow_read_ctr);
+	/* avoid up_read()->rwsem_release() */
+	__up_read(&brw->rw_sem);
+}
+
+void percpu_up_read(struct percpu_rw_semaphore *brw)
+{
+	rwsem_release(&brw->rw_sem.dep_map, 1, _RET_IP_);
+
+	if (likely(update_fast_ctr(brw, -1)))
+		return;
+
+	/* false-positive is possible but harmless */
+	if (atomic_dec_and_test(&brw->slow_read_ctr))
+		wake_up_all(&brw->write_waitq);
+}
+
+static int clear_fast_ctr(struct percpu_rw_semaphore *brw)
+{
+	unsigned int sum = 0;
+	int cpu;
+
+	for_each_possible_cpu(cpu) {
+		sum += per_cpu(*brw->fast_read_ctr, cpu);
+		per_cpu(*brw->fast_read_ctr, cpu) = 0;
+	}
+
+	return sum;
+}
+
+/*
+ * A writer increments ->write_ctr to force the readers to switch to the
+ * slow mode, note the atomic_read() check in update_fast_ctr().
+ *
+ * After that the readers can only inc/dec the slow ->slow_read_ctr counter,
+ * ->fast_read_ctr is stable. Once the writer moves its sum into the slow
+ * counter it represents the number of active readers.
+ *
+ * Finally the writer takes ->rw_sem for writing and blocks the new readers,
+ * then waits until the slow counter becomes zero.
+ */
+void percpu_down_write(struct percpu_rw_semaphore *brw)
+{
+	/* tell update_fast_ctr() there is a pending writer */
+	atomic_inc(&brw->write_ctr);
+	/*
+	 * 1. Ensures that write_ctr != 0 is visible to any down_read/up_read
+	 *    so that update_fast_ctr() can't succeed.
+	 *
+	 * 2. Ensures we see the result of every previous this_cpu_add() in
+	 *    update_fast_ctr().
+	 *
+	 * 3. Ensures that if any reader has exited its critical section via
+	 *    fast-path, it executes a full memory barrier before we return.
+	 *    See R_W case in the comment above update_fast_ctr().
+	 */
+	synchronize_sched_expedited();
+
+	/* exclude other writers, and block the new readers completely */
+	down_write(&brw->rw_sem);
+
+	/* nobody can use fast_read_ctr, move its sum into slow_read_ctr */
+	atomic_add(clear_fast_ctr(brw), &brw->slow_read_ctr);
+
+	/* wait for all readers to complete their percpu_up_read() */
+	wait_event(brw->write_waitq, !atomic_read(&brw->slow_read_ctr));
+}
+
+void percpu_up_write(struct percpu_rw_semaphore *brw)
+{
+	/* release the lock, but the readers can't use the fast-path */
+	up_write(&brw->rw_sem);
+	/*
+	 * Insert the barrier before the next fast-path in down_read,
+	 * see W_R case in the comment above update_fast_ctr().
+	 */
+	synchronize_sched_expedited();
+	/* the last writer unblocks update_fast_ctr() */
+	atomic_dec(&brw->write_ctr);
+}
diff --git a/kernel/locking/qrwlock.c b/kernel/locking/qrwlock.c
new file mode 100644
index 000000000..f956ede7f
--- /dev/null
+++ b/kernel/locking/qrwlock.c
@@ -0,0 +1,132 @@
+/*
+ * Queue read/write lock
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * (C) Copyright 2013-2014 Hewlett-Packard Development Company, L.P.
+ *
+ * Authors: Waiman Long <waiman.long@hp.com>
+ */
+#include <linux/smp.h>
+#include <linux/bug.h>
+#include <linux/cpumask.h>
+#include <linux/percpu.h>
+#include <linux/hardirq.h>
+#include <asm/qrwlock.h>
+
+/**
+ * rspin_until_writer_unlock - inc reader count & spin until writer is gone
+ * @lock  : Pointer to queue rwlock structure
+ * @writer: Current queue rwlock writer status byte
+ *
+ * In interrupt context or at the head of the queue, the reader will just
+ * increment the reader count & wait until the writer releases the lock.
+ */
+static __always_inline void
+rspin_until_writer_unlock(struct qrwlock *lock, u32 cnts)
+{
+	while ((cnts & _QW_WMASK) == _QW_LOCKED) {
+		cpu_relax_lowlatency();
+		cnts = smp_load_acquire((u32 *)&lock->cnts);
+	}
+}
+
+/**
+ * queue_read_lock_slowpath - acquire read lock of a queue rwlock
+ * @lock: Pointer to queue rwlock structure
+ */
+void queue_read_lock_slowpath(struct qrwlock *lock)
+{
+	u32 cnts;
+
+	/*
+	 * Readers come here when they cannot get the lock without waiting
+	 */
+	if (unlikely(in_interrupt())) {
+		/*
+		 * Readers in interrupt context will spin until the lock is
+		 * available without waiting in the queue.
+		 */
+		cnts = smp_load_acquire((u32 *)&lock->cnts);
+		rspin_until_writer_unlock(lock, cnts);
+		return;
+	}
+	atomic_sub(_QR_BIAS, &lock->cnts);
+
+	/*
+	 * Put the reader into the wait queue
+	 */
+	arch_spin_lock(&lock->lock);
+
+	/*
+	 * At the head of the wait queue now, wait until the writer state
+	 * goes to 0 and then try to increment the reader count and get
+	 * the lock. It is possible that an incoming writer may steal the
+	 * lock in the interim, so it is necessary to check the writer byte
+	 * to make sure that the write lock isn't taken.
+	 */
+	while (atomic_read(&lock->cnts) & _QW_WMASK)
+		cpu_relax_lowlatency();
+
+	cnts = atomic_add_return(_QR_BIAS, &lock->cnts) - _QR_BIAS;
+	rspin_until_writer_unlock(lock, cnts);
+
+	/*
+	 * Signal the next one in queue to become queue head
+	 */
+	arch_spin_unlock(&lock->lock);
+}
+EXPORT_SYMBOL(queue_read_lock_slowpath);
+
+/**
+ * queue_write_lock_slowpath - acquire write lock of a queue rwlock
+ * @lock : Pointer to queue rwlock structure
+ */
+void queue_write_lock_slowpath(struct qrwlock *lock)
+{
+	u32 cnts;
+
+	/* Put the writer into the wait queue */
+	arch_spin_lock(&lock->lock);
+
+	/* Try to acquire the lock directly if no reader is present */
+	if (!atomic_read(&lock->cnts) &&
+	    (atomic_cmpxchg(&lock->cnts, 0, _QW_LOCKED) == 0))
+		goto unlock;
+
+	/*
+	 * Set the waiting flag to notify readers that a writer is pending,
+	 * or wait for a previous writer to go away.
+	 */
+	for (;;) {
+		cnts = atomic_read(&lock->cnts);
+		if (!(cnts & _QW_WMASK) &&
+		    (atomic_cmpxchg(&lock->cnts, cnts,
+				    cnts | _QW_WAITING) == cnts))
+			break;
+
+		cpu_relax_lowlatency();
+	}
+
+	/* When no more readers, set the locked flag */
+	for (;;) {
+		cnts = atomic_read(&lock->cnts);
+		if ((cnts == _QW_WAITING) &&
+		    (atomic_cmpxchg(&lock->cnts, _QW_WAITING,
+				    _QW_LOCKED) == _QW_WAITING))
+			break;
+
+		cpu_relax_lowlatency();
+	}
+unlock:
+	arch_spin_unlock(&lock->lock);
+}
+EXPORT_SYMBOL(queue_write_lock_slowpath);
diff --git a/kernel/locking/rtmutex-debug.c b/kernel/locking/rtmutex-debug.c
new file mode 100644
index 000000000..62b6cee8e
--- /dev/null
+++ b/kernel/locking/rtmutex-debug.c
@@ -0,0 +1,184 @@
+/*
+ * RT-Mutexes: blocking mutual exclusion locks with PI support
+ *
+ * started by Ingo Molnar and Thomas Gleixner:
+ *
+ *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *  Copyright (C) 2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com>
+ *
+ * This code is based on the rt.c implementation in the preempt-rt tree.
+ * Portions of said code are
+ *
+ *  Copyright (C) 2004  LynuxWorks, Inc., Igor Manyilov, Bill Huey
+ *  Copyright (C) 2006  Esben Nielsen
+ *  Copyright (C) 2006  Kihon Technologies Inc.,
+ *			Steven Rostedt <rostedt@goodmis.org>
+ *
+ * See rt.c in preempt-rt for proper credits and further information
+ */
+#include <linux/sched.h>
+#include <linux/sched/rt.h>
+#include <linux/delay.h>
+#include <linux/export.h>
+#include <linux/spinlock.h>
+#include <linux/kallsyms.h>
+#include <linux/syscalls.h>
+#include <linux/interrupt.h>
+#include <linux/rbtree.h>
+#include <linux/fs.h>
+#include <linux/debug_locks.h>
+
+#include "rtmutex_common.h"
+
+static void printk_task(struct task_struct *p)
+{
+	if (p)
+		printk("%16s:%5d [%p, %3d]", p->comm, task_pid_nr(p), p, p->prio);
+	else
+		printk("<none>");
+}
+
+static void printk_lock(struct rt_mutex *lock, int print_owner)
+{
+	if (lock->name)
+		printk(" [%p] {%s}\n",
+			lock, lock->name);
+	else
+		printk(" [%p] {%s:%d}\n",
+			lock, lock->file, lock->line);
+
+	if (print_owner && rt_mutex_owner(lock)) {
+		printk(".. ->owner: %p\n", lock->owner);
+		printk(".. held by:  ");
+		printk_task(rt_mutex_owner(lock));
+		printk("\n");
+	}
+}
+
+void rt_mutex_debug_task_free(struct task_struct *task)
+{
+	DEBUG_LOCKS_WARN_ON(!RB_EMPTY_ROOT(&task->pi_waiters));
+	DEBUG_LOCKS_WARN_ON(task->pi_blocked_on);
+}
+
+/*
+ * We fill out the fields in the waiter to store the information about
+ * the deadlock. We print when we return. act_waiter can be NULL in
+ * case of a remove waiter operation.
+ */
+void debug_rt_mutex_deadlock(enum rtmutex_chainwalk chwalk,
+			     struct rt_mutex_waiter *act_waiter,
+			     struct rt_mutex *lock)
+{
+	struct task_struct *task;
+
+	if (!debug_locks || chwalk == RT_MUTEX_FULL_CHAINWALK || !act_waiter)
+		return;
+
+	task = rt_mutex_owner(act_waiter->lock);
+	if (task && task != current) {
+		act_waiter->deadlock_task_pid = get_pid(task_pid(task));
+		act_waiter->deadlock_lock = lock;
+	}
+}
+
+void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter)
+{
+	struct task_struct *task;
+
+	if (!waiter->deadlock_lock || !debug_locks)
+		return;
+
+	rcu_read_lock();
+	task = pid_task(waiter->deadlock_task_pid, PIDTYPE_PID);
+	if (!task) {
+		rcu_read_unlock();
+		return;
+	}
+
+	if (!debug_locks_off()) {
+		rcu_read_unlock();
+		return;
+	}
+
+	printk("\n============================================\n");
+	printk(  "[ BUG: circular locking deadlock detected! ]\n");
+	printk("%s\n", print_tainted());
+	printk(  "--------------------------------------------\n");
+	printk("%s/%d is deadlocking current task %s/%d\n\n",
+	       task->comm, task_pid_nr(task),
+	       current->comm, task_pid_nr(current));
+
+	printk("\n1) %s/%d is trying to acquire this lock:\n",
+	       current->comm, task_pid_nr(current));
+	printk_lock(waiter->lock, 1);
+
+	printk("\n2) %s/%d is blocked on this lock:\n",
+		task->comm, task_pid_nr(task));
+	printk_lock(waiter->deadlock_lock, 1);
+
+	debug_show_held_locks(current);
+	debug_show_held_locks(task);
+
+	printk("\n%s/%d's [blocked] stackdump:\n\n",
+		task->comm, task_pid_nr(task));
+	show_stack(task, NULL);
+	printk("\n%s/%d's [current] stackdump:\n\n",
+		current->comm, task_pid_nr(current));
+	dump_stack();
+	debug_show_all_locks();
+	rcu_read_unlock();
+
+	printk("[ turning off deadlock detection."
+	       "Please report this trace. ]\n\n");
+}
+
+void debug_rt_mutex_lock(struct rt_mutex *lock)
+{
+}
+
+void debug_rt_mutex_unlock(struct rt_mutex *lock)
+{
+	DEBUG_LOCKS_WARN_ON(rt_mutex_owner(lock) != current);
+}
+
+void
+debug_rt_mutex_proxy_lock(struct rt_mutex *lock, struct task_struct *powner)
+{
+}
+
+void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock)
+{
+	DEBUG_LOCKS_WARN_ON(!rt_mutex_owner(lock));
+}
+
+void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
+{
+	memset(waiter, 0x11, sizeof(*waiter));
+	waiter->deadlock_task_pid = NULL;
+}
+
+void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
+{
+	put_pid(waiter->deadlock_task_pid);
+	memset(waiter, 0x22, sizeof(*waiter));
+}
+
+void debug_rt_mutex_init(struct rt_mutex *lock, const char *name)
+{
+	/*
+	 * Make sure we are not reinitializing a held lock:
+	 */
+	debug_check_no_locks_freed((void *)lock, sizeof(*lock));
+	lock->name = name;
+}
+
+void
+rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task)
+{
+}
+
+void rt_mutex_deadlock_account_unlock(struct task_struct *task)
+{
+}
+
diff --git a/kernel/locking/rtmutex-debug.h b/kernel/locking/rtmutex-debug.h
new file mode 100644
index 000000000..d0519c343
--- /dev/null
+++ b/kernel/locking/rtmutex-debug.h
@@ -0,0 +1,39 @@
+/*
+ * RT-Mutexes: blocking mutual exclusion locks with PI support
+ *
+ * started by Ingo Molnar and Thomas Gleixner:
+ *
+ *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *  Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
+ *
+ * This file contains macros used solely by rtmutex.c. Debug version.
+ */
+
+extern void
+rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task);
+extern void rt_mutex_deadlock_account_unlock(struct task_struct *task);
+extern void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter);
+extern void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter);
+extern void debug_rt_mutex_init(struct rt_mutex *lock, const char *name);
+extern void debug_rt_mutex_lock(struct rt_mutex *lock);
+extern void debug_rt_mutex_unlock(struct rt_mutex *lock);
+extern void debug_rt_mutex_proxy_lock(struct rt_mutex *lock,
+				      struct task_struct *powner);
+extern void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock);
+extern void debug_rt_mutex_deadlock(enum rtmutex_chainwalk chwalk,
+				    struct rt_mutex_waiter *waiter,
+				    struct rt_mutex *lock);
+extern void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter);
+# define debug_rt_mutex_reset_waiter(w)			\
+	do { (w)->deadlock_lock = NULL; } while (0)
+
+static inline bool debug_rt_mutex_detect_deadlock(struct rt_mutex_waiter *waiter,
+						  enum rtmutex_chainwalk walk)
+{
+	return (waiter != NULL);
+}
+
+static inline void rt_mutex_print_deadlock(struct rt_mutex_waiter *w)
+{
+	debug_rt_mutex_print_deadlock(w);
+}
diff --git a/kernel/locking/rtmutex-tester.c b/kernel/locking/rtmutex-tester.c
new file mode 100644
index 000000000..1d96dd0d9
--- /dev/null
+++ b/kernel/locking/rtmutex-tester.c
@@ -0,0 +1,420 @@
+/*
+ * RT-Mutex-tester: scriptable tester for rt mutexes
+ *
+ * started by Thomas Gleixner:
+ *
+ *  Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
+ *
+ */
+#include <linux/device.h>
+#include <linux/kthread.h>
+#include <linux/export.h>
+#include <linux/sched.h>
+#include <linux/sched/rt.h>
+#include <linux/spinlock.h>
+#include <linux/timer.h>
+#include <linux/freezer.h>
+#include <linux/stat.h>
+
+#include "rtmutex.h"
+
+#define MAX_RT_TEST_THREADS	8
+#define MAX_RT_TEST_MUTEXES	8
+
+static spinlock_t rttest_lock;
+static atomic_t rttest_event;
+
+struct test_thread_data {
+	int			opcode;
+	int			opdata;
+	int			mutexes[MAX_RT_TEST_MUTEXES];
+	int			event;
+	struct device		dev;
+};
+
+static struct test_thread_data thread_data[MAX_RT_TEST_THREADS];
+static struct task_struct *threads[MAX_RT_TEST_THREADS];
+static struct rt_mutex mutexes[MAX_RT_TEST_MUTEXES];
+
+enum test_opcodes {
+	RTTEST_NOP = 0,
+	RTTEST_SCHEDOT,		/* 1 Sched other, data = nice */
+	RTTEST_SCHEDRT,		/* 2 Sched fifo, data = prio */
+	RTTEST_LOCK,		/* 3 Lock uninterruptible, data = lockindex */
+	RTTEST_LOCKNOWAIT,	/* 4 Lock uninterruptible no wait in wakeup, data = lockindex */
+	RTTEST_LOCKINT,		/* 5 Lock interruptible, data = lockindex */
+	RTTEST_LOCKINTNOWAIT,	/* 6 Lock interruptible no wait in wakeup, data = lockindex */
+	RTTEST_LOCKCONT,	/* 7 Continue locking after the wakeup delay */
+	RTTEST_UNLOCK,		/* 8 Unlock, data = lockindex */
+	/* 9, 10 - reserved for BKL commemoration */
+	RTTEST_SIGNAL = 11,	/* 11 Signal other test thread, data = thread id */
+	RTTEST_RESETEVENT = 98,	/* 98 Reset event counter */
+	RTTEST_RESET = 99,	/* 99 Reset all pending operations */
+};
+
+static int handle_op(struct test_thread_data *td, int lockwakeup)
+{
+	int i, id, ret = -EINVAL;
+
+	switch(td->opcode) {
+
+	case RTTEST_NOP:
+		return 0;
+
+	case RTTEST_LOCKCONT:
+		td->mutexes[td->opdata] = 1;
+		td->event = atomic_add_return(1, &rttest_event);
+		return 0;
+
+	case RTTEST_RESET:
+		for (i = 0; i < MAX_RT_TEST_MUTEXES; i++) {
+			if (td->mutexes[i] == 4) {
+				rt_mutex_unlock(&mutexes[i]);
+				td->mutexes[i] = 0;
+			}
+		}
+		return 0;
+
+	case RTTEST_RESETEVENT:
+		atomic_set(&rttest_event, 0);
+		return 0;
+
+	default:
+		if (lockwakeup)
+			return ret;
+	}
+
+	switch(td->opcode) {
+
+	case RTTEST_LOCK:
+	case RTTEST_LOCKNOWAIT:
+		id = td->opdata;
+		if (id < 0 || id >= MAX_RT_TEST_MUTEXES)
+			return ret;
+
+		td->mutexes[id] = 1;
+		td->event = atomic_add_return(1, &rttest_event);
+		rt_mutex_lock(&mutexes[id]);
+		td->event = atomic_add_return(1, &rttest_event);
+		td->mutexes[id] = 4;
+		return 0;
+
+	case RTTEST_LOCKINT:
+	case RTTEST_LOCKINTNOWAIT:
+		id = td->opdata;
+		if (id < 0 || id >= MAX_RT_TEST_MUTEXES)
+			return ret;
+
+		td->mutexes[id] = 1;
+		td->event = atomic_add_return(1, &rttest_event);
+		ret = rt_mutex_lock_interruptible(&mutexes[id], 0);
+		td->event = atomic_add_return(1, &rttest_event);
+		td->mutexes[id] = ret ? 0 : 4;
+		return ret ? -EINTR : 0;
+
+	case RTTEST_UNLOCK:
+		id = td->opdata;
+		if (id < 0 || id >= MAX_RT_TEST_MUTEXES || td->mutexes[id] != 4)
+			return ret;
+
+		td->event = atomic_add_return(1, &rttest_event);
+		rt_mutex_unlock(&mutexes[id]);
+		td->event = atomic_add_return(1, &rttest_event);
+		td->mutexes[id] = 0;
+		return 0;
+
+	default:
+		break;
+	}
+	return ret;
+}
+
+/*
+ * Schedule replacement for rtsem_down(). Only called for threads with
+ * PF_MUTEX_TESTER set.
+ *
+ * This allows us to have finegrained control over the event flow.
+ *
+ */
+void schedule_rt_mutex_test(struct rt_mutex *mutex)
+{
+	int tid, op, dat;
+	struct test_thread_data *td;
+
+	/* We have to lookup the task */
+	for (tid = 0; tid < MAX_RT_TEST_THREADS; tid++) {
+		if (threads[tid] == current)
+			break;
+	}
+
+	BUG_ON(tid == MAX_RT_TEST_THREADS);
+
+	td = &thread_data[tid];
+
+	op = td->opcode;
+	dat = td->opdata;
+
+	switch (op) {
+	case RTTEST_LOCK:
+	case RTTEST_LOCKINT:
+	case RTTEST_LOCKNOWAIT:
+	case RTTEST_LOCKINTNOWAIT:
+		if (mutex != &mutexes[dat])
+			break;
+
+		if (td->mutexes[dat] != 1)
+			break;
+
+		td->mutexes[dat] = 2;
+		td->event = atomic_add_return(1, &rttest_event);
+		break;
+
+	default:
+		break;
+	}
+
+	schedule();
+
+
+	switch (op) {
+	case RTTEST_LOCK:
+	case RTTEST_LOCKINT:
+		if (mutex != &mutexes[dat])
+			return;
+
+		if (td->mutexes[dat] != 2)
+			return;
+
+		td->mutexes[dat] = 3;
+		td->event = atomic_add_return(1, &rttest_event);
+		break;
+
+	case RTTEST_LOCKNOWAIT:
+	case RTTEST_LOCKINTNOWAIT:
+		if (mutex != &mutexes[dat])
+			return;
+
+		if (td->mutexes[dat] != 2)
+			return;
+
+		td->mutexes[dat] = 1;
+		td->event = atomic_add_return(1, &rttest_event);
+		return;
+
+	default:
+		return;
+	}
+
+	td->opcode = 0;
+
+	for (;;) {
+		set_current_state(TASK_INTERRUPTIBLE);
+
+		if (td->opcode > 0) {
+			int ret;
+
+			set_current_state(TASK_RUNNING);
+			ret = handle_op(td, 1);
+			set_current_state(TASK_INTERRUPTIBLE);
+			if (td->opcode == RTTEST_LOCKCONT)
+				break;
+			td->opcode = ret;
+		}
+
+		/* Wait for the next command to be executed */
+		schedule();
+	}
+
+	/* Restore previous command and data */
+	td->opcode = op;
+	td->opdata = dat;
+}
+
+static int test_func(void *data)
+{
+	struct test_thread_data *td = data;
+	int ret;
+
+	current->flags |= PF_MUTEX_TESTER;
+	set_freezable();
+	allow_signal(SIGHUP);
+
+	for(;;) {
+
+		set_current_state(TASK_INTERRUPTIBLE);
+
+		if (td->opcode > 0) {
+			set_current_state(TASK_RUNNING);
+			ret = handle_op(td, 0);
+			set_current_state(TASK_INTERRUPTIBLE);
+			td->opcode = ret;
+		}
+
+		/* Wait for the next command to be executed */
+		schedule();
+		try_to_freeze();
+
+		if (signal_pending(current))
+			flush_signals(current);
+
+		if(kthread_should_stop())
+			break;
+	}
+	return 0;
+}
+
+/**
+ * sysfs_test_command - interface for test commands
+ * @dev:	thread reference
+ * @buf:	command for actual step
+ * @count:	length of buffer
+ *
+ * command syntax:
+ *
+ * opcode:data
+ */
+static ssize_t sysfs_test_command(struct device *dev, struct device_attribute *attr,
+				  const char *buf, size_t count)
+{
+	struct sched_param schedpar;
+	struct test_thread_data *td;
+	char cmdbuf[32];
+	int op, dat, tid, ret;
+
+	td = container_of(dev, struct test_thread_data, dev);
+	tid = td->dev.id;
+
+	/* strings from sysfs write are not 0 terminated! */
+	if (count >= sizeof(cmdbuf))
+		return -EINVAL;
+
+	/* strip of \n: */
+	if (buf[count-1] == '\n')
+		count--;
+	if (count < 1)
+		return -EINVAL;
+
+	memcpy(cmdbuf, buf, count);
+	cmdbuf[count] = 0;
+
+	if (sscanf(cmdbuf, "%d:%d", &op, &dat) != 2)
+		return -EINVAL;
+
+	switch (op) {
+	case RTTEST_SCHEDOT:
+		schedpar.sched_priority = 0;
+		ret = sched_setscheduler(threads[tid], SCHED_NORMAL, &schedpar);
+		if (ret)
+			return ret;
+		set_user_nice(current, 0);
+		break;
+
+	case RTTEST_SCHEDRT:
+		schedpar.sched_priority = dat;
+		ret = sched_setscheduler(threads[tid], SCHED_FIFO, &schedpar);
+		if (ret)
+			return ret;
+		break;
+
+	case RTTEST_SIGNAL:
+		send_sig(SIGHUP, threads[tid], 0);
+		break;
+
+	default:
+		if (td->opcode > 0)
+			return -EBUSY;
+		td->opdata = dat;
+		td->opcode = op;
+		wake_up_process(threads[tid]);
+	}
+
+	return count;
+}
+
+/**
+ * sysfs_test_status - sysfs interface for rt tester
+ * @dev:	thread to query
+ * @buf:	char buffer to be filled with thread status info
+ */
+static ssize_t sysfs_test_status(struct device *dev, struct device_attribute *attr,
+				 char *buf)
+{
+	struct test_thread_data *td;
+	struct task_struct *tsk;
+	char *curr = buf;
+	int i;
+
+	td = container_of(dev, struct test_thread_data, dev);
+	tsk = threads[td->dev.id];
+
+	spin_lock(&rttest_lock);
+
+	curr += sprintf(curr,
+		"O: %4d, E:%8d, S: 0x%08lx, P: %4d, N: %4d, B: %p, M:",
+		td->opcode, td->event, tsk->state,
+			(MAX_RT_PRIO - 1) - tsk->prio,
+			(MAX_RT_PRIO - 1) - tsk->normal_prio,
+		tsk->pi_blocked_on);
+
+	for (i = MAX_RT_TEST_MUTEXES - 1; i >=0 ; i--)
+		curr += sprintf(curr, "%d", td->mutexes[i]);
+
+	spin_unlock(&rttest_lock);
+
+	curr += sprintf(curr, ", T: %p, R: %p\n", tsk,
+			mutexes[td->dev.id].owner);
+
+	return curr - buf;
+}
+
+static DEVICE_ATTR(status, S_IRUSR, sysfs_test_status, NULL);
+static DEVICE_ATTR(command, S_IWUSR, NULL, sysfs_test_command);
+
+static struct bus_type rttest_subsys = {
+	.name = "rttest",
+	.dev_name = "rttest",
+};
+
+static int init_test_thread(int id)
+{
+	thread_data[id].dev.bus = &rttest_subsys;
+	thread_data[id].dev.id = id;
+
+	threads[id] = kthread_run(test_func, &thread_data[id], "rt-test-%d", id);
+	if (IS_ERR(threads[id]))
+		return PTR_ERR(threads[id]);
+
+	return device_register(&thread_data[id].dev);
+}
+
+static int init_rttest(void)
+{
+	int ret, i;
+
+	spin_lock_init(&rttest_lock);
+
+	for (i = 0; i < MAX_RT_TEST_MUTEXES; i++)
+		rt_mutex_init(&mutexes[i]);
+
+	ret = subsys_system_register(&rttest_subsys, NULL);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < MAX_RT_TEST_THREADS; i++) {
+		ret = init_test_thread(i);
+		if (ret)
+			break;
+		ret = device_create_file(&thread_data[i].dev, &dev_attr_status);
+		if (ret)
+			break;
+		ret = device_create_file(&thread_data[i].dev, &dev_attr_command);
+		if (ret)
+			break;
+	}
+
+	printk("Initializing RT-Tester: %s\n", ret ? "Failed" : "OK" );
+
+	return ret;
+}
+
+device_initcall(init_rttest);
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
new file mode 100644
index 000000000..b025295f4
--- /dev/null
+++ b/kernel/locking/rtmutex.c
@@ -0,0 +1,1648 @@
+/*
+ * RT-Mutexes: simple blocking mutual exclusion locks with PI support
+ *
+ * started by Ingo Molnar and Thomas Gleixner.
+ *
+ *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *  Copyright (C) 2005-2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com>
+ *  Copyright (C) 2005 Kihon Technologies Inc., Steven Rostedt
+ *  Copyright (C) 2006 Esben Nielsen
+ *
+ *  See Documentation/locking/rt-mutex-design.txt for details.
+ */
+#include <linux/spinlock.h>
+#include <linux/export.h>
+#include <linux/sched.h>
+#include <linux/sched/rt.h>
+#include <linux/sched/deadline.h>
+#include <linux/timer.h>
+
+#include "rtmutex_common.h"
+
+/*
+ * lock->owner state tracking:
+ *
+ * lock->owner holds the task_struct pointer of the owner. Bit 0
+ * is used to keep track of the "lock has waiters" state.
+ *
+ * owner	bit0
+ * NULL		0	lock is free (fast acquire possible)
+ * NULL		1	lock is free and has waiters and the top waiter
+ *				is going to take the lock*
+ * taskpointer	0	lock is held (fast release possible)
+ * taskpointer	1	lock is held and has waiters**
+ *
+ * The fast atomic compare exchange based acquire and release is only
+ * possible when bit 0 of lock->owner is 0.
+ *
+ * (*) It also can be a transitional state when grabbing the lock
+ * with ->wait_lock is held. To prevent any fast path cmpxchg to the lock,
+ * we need to set the bit0 before looking at the lock, and the owner may be
+ * NULL in this small time, hence this can be a transitional state.
+ *
+ * (**) There is a small time when bit 0 is set but there are no
+ * waiters. This can happen when grabbing the lock in the slow path.
+ * To prevent a cmpxchg of the owner releasing the lock, we need to
+ * set this bit before looking at the lock.
+ */
+
+static void
+rt_mutex_set_owner(struct rt_mutex *lock, struct task_struct *owner)
+{
+	unsigned long val = (unsigned long)owner;
+
+	if (rt_mutex_has_waiters(lock))
+		val |= RT_MUTEX_HAS_WAITERS;
+
+	lock->owner = (struct task_struct *)val;
+}
+
+static inline void clear_rt_mutex_waiters(struct rt_mutex *lock)
+{
+	lock->owner = (struct task_struct *)
+			((unsigned long)lock->owner & ~RT_MUTEX_HAS_WAITERS);
+}
+
+static void fixup_rt_mutex_waiters(struct rt_mutex *lock)
+{
+	if (!rt_mutex_has_waiters(lock))
+		clear_rt_mutex_waiters(lock);
+}
+
+/*
+ * We can speed up the acquire/release, if the architecture
+ * supports cmpxchg and if there's no debugging state to be set up
+ */
+#if defined(__HAVE_ARCH_CMPXCHG) && !defined(CONFIG_DEBUG_RT_MUTEXES)
+# define rt_mutex_cmpxchg(l,c,n)	(cmpxchg(&l->owner, c, n) == c)
+static inline void mark_rt_mutex_waiters(struct rt_mutex *lock)
+{
+	unsigned long owner, *p = (unsigned long *) &lock->owner;
+
+	do {
+		owner = *p;
+	} while (cmpxchg(p, owner, owner | RT_MUTEX_HAS_WAITERS) != owner);
+}
+
+/*
+ * Safe fastpath aware unlock:
+ * 1) Clear the waiters bit
+ * 2) Drop lock->wait_lock
+ * 3) Try to unlock the lock with cmpxchg
+ */
+static inline bool unlock_rt_mutex_safe(struct rt_mutex *lock)
+	__releases(lock->wait_lock)
+{
+	struct task_struct *owner = rt_mutex_owner(lock);
+
+	clear_rt_mutex_waiters(lock);
+	raw_spin_unlock(&lock->wait_lock);
+	/*
+	 * If a new waiter comes in between the unlock and the cmpxchg
+	 * we have two situations:
+	 *
+	 * unlock(wait_lock);
+	 *					lock(wait_lock);
+	 * cmpxchg(p, owner, 0) == owner
+	 *					mark_rt_mutex_waiters(lock);
+	 *					acquire(lock);
+	 * or:
+	 *
+	 * unlock(wait_lock);
+	 *					lock(wait_lock);
+	 *					mark_rt_mutex_waiters(lock);
+	 *
+	 * cmpxchg(p, owner, 0) != owner
+	 *					enqueue_waiter();
+	 *					unlock(wait_lock);
+	 * lock(wait_lock);
+	 * wake waiter();
+	 * unlock(wait_lock);
+	 *					lock(wait_lock);
+	 *					acquire(lock);
+	 */
+	return rt_mutex_cmpxchg(lock, owner, NULL);
+}
+
+#else
+# define rt_mutex_cmpxchg(l,c,n)	(0)
+static inline void mark_rt_mutex_waiters(struct rt_mutex *lock)
+{
+	lock->owner = (struct task_struct *)
+			((unsigned long)lock->owner | RT_MUTEX_HAS_WAITERS);
+}
+
+/*
+ * Simple slow path only version: lock->owner is protected by lock->wait_lock.
+ */
+static inline bool unlock_rt_mutex_safe(struct rt_mutex *lock)
+	__releases(lock->wait_lock)
+{
+	lock->owner = NULL;
+	raw_spin_unlock(&lock->wait_lock);
+	return true;
+}
+#endif
+
+static inline int
+rt_mutex_waiter_less(struct rt_mutex_waiter *left,
+		     struct rt_mutex_waiter *right)
+{
+	if (left->prio < right->prio)
+		return 1;
+
+	/*
+	 * If both waiters have dl_prio(), we check the deadlines of the
+	 * associated tasks.
+	 * If left waiter has a dl_prio(), and we didn't return 1 above,
+	 * then right waiter has a dl_prio() too.
+	 */
+	if (dl_prio(left->prio))
+		return (left->task->dl.deadline < right->task->dl.deadline);
+
+	return 0;
+}
+
+static void
+rt_mutex_enqueue(struct rt_mutex *lock, struct rt_mutex_waiter *waiter)
+{
+	struct rb_node **link = &lock->waiters.rb_node;
+	struct rb_node *parent = NULL;
+	struct rt_mutex_waiter *entry;
+	int leftmost = 1;
+
+	while (*link) {
+		parent = *link;
+		entry = rb_entry(parent, struct rt_mutex_waiter, tree_entry);
+		if (rt_mutex_waiter_less(waiter, entry)) {
+			link = &parent->rb_left;
+		} else {
+			link = &parent->rb_right;
+			leftmost = 0;
+		}
+	}
+
+	if (leftmost)
+		lock->waiters_leftmost = &waiter->tree_entry;
+
+	rb_link_node(&waiter->tree_entry, parent, link);
+	rb_insert_color(&waiter->tree_entry, &lock->waiters);
+}
+
+static void
+rt_mutex_dequeue(struct rt_mutex *lock, struct rt_mutex_waiter *waiter)
+{
+	if (RB_EMPTY_NODE(&waiter->tree_entry))
+		return;
+
+	if (lock->waiters_leftmost == &waiter->tree_entry)
+		lock->waiters_leftmost = rb_next(&waiter->tree_entry);
+
+	rb_erase(&waiter->tree_entry, &lock->waiters);
+	RB_CLEAR_NODE(&waiter->tree_entry);
+}
+
+static void
+rt_mutex_enqueue_pi(struct task_struct *task, struct rt_mutex_waiter *waiter)
+{
+	struct rb_node **link = &task->pi_waiters.rb_node;
+	struct rb_node *parent = NULL;
+	struct rt_mutex_waiter *entry;
+	int leftmost = 1;
+
+	while (*link) {
+		parent = *link;
+		entry = rb_entry(parent, struct rt_mutex_waiter, pi_tree_entry);
+		if (rt_mutex_waiter_less(waiter, entry)) {
+			link = &parent->rb_left;
+		} else {
+			link = &parent->rb_right;
+			leftmost = 0;
+		}
+	}
+
+	if (leftmost)
+		task->pi_waiters_leftmost = &waiter->pi_tree_entry;
+
+	rb_link_node(&waiter->pi_tree_entry, parent, link);
+	rb_insert_color(&waiter->pi_tree_entry, &task->pi_waiters);
+}
+
+static void
+rt_mutex_dequeue_pi(struct task_struct *task, struct rt_mutex_waiter *waiter)
+{
+	if (RB_EMPTY_NODE(&waiter->pi_tree_entry))
+		return;
+
+	if (task->pi_waiters_leftmost == &waiter->pi_tree_entry)
+		task->pi_waiters_leftmost = rb_next(&waiter->pi_tree_entry);
+
+	rb_erase(&waiter->pi_tree_entry, &task->pi_waiters);
+	RB_CLEAR_NODE(&waiter->pi_tree_entry);
+}
+
+/*
+ * Calculate task priority from the waiter tree priority
+ *
+ * Return task->normal_prio when the waiter tree is empty or when
+ * the waiter is not allowed to do priority boosting
+ */
+int rt_mutex_getprio(struct task_struct *task)
+{
+	if (likely(!task_has_pi_waiters(task)))
+		return task->normal_prio;
+
+	return min(task_top_pi_waiter(task)->prio,
+		   task->normal_prio);
+}
+
+struct task_struct *rt_mutex_get_top_task(struct task_struct *task)
+{
+	if (likely(!task_has_pi_waiters(task)))
+		return NULL;
+
+	return task_top_pi_waiter(task)->task;
+}
+
+/*
+ * Called by sched_setscheduler() to get the priority which will be
+ * effective after the change.
+ */
+int rt_mutex_get_effective_prio(struct task_struct *task, int newprio)
+{
+	if (!task_has_pi_waiters(task))
+		return newprio;
+
+	if (task_top_pi_waiter(task)->task->prio <= newprio)
+		return task_top_pi_waiter(task)->task->prio;
+	return newprio;
+}
+
+/*
+ * Adjust the priority of a task, after its pi_waiters got modified.
+ *
+ * This can be both boosting and unboosting. task->pi_lock must be held.
+ */
+static void __rt_mutex_adjust_prio(struct task_struct *task)
+{
+	int prio = rt_mutex_getprio(task);
+
+	if (task->prio != prio || dl_prio(prio))
+		rt_mutex_setprio(task, prio);
+}
+
+/*
+ * Adjust task priority (undo boosting). Called from the exit path of
+ * rt_mutex_slowunlock() and rt_mutex_slowlock().
+ *
+ * (Note: We do this outside of the protection of lock->wait_lock to
+ * allow the lock to be taken while or before we readjust the priority
+ * of task. We do not use the spin_xx_mutex() variants here as we are
+ * outside of the debug path.)
+ */
+static void rt_mutex_adjust_prio(struct task_struct *task)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&task->pi_lock, flags);
+	__rt_mutex_adjust_prio(task);
+	raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+}
+
+/*
+ * Deadlock detection is conditional:
+ *
+ * If CONFIG_DEBUG_RT_MUTEXES=n, deadlock detection is only conducted
+ * if the detect argument is == RT_MUTEX_FULL_CHAINWALK.
+ *
+ * If CONFIG_DEBUG_RT_MUTEXES=y, deadlock detection is always
+ * conducted independent of the detect argument.
+ *
+ * If the waiter argument is NULL this indicates the deboost path and
+ * deadlock detection is disabled independent of the detect argument
+ * and the config settings.
+ */
+static bool rt_mutex_cond_detect_deadlock(struct rt_mutex_waiter *waiter,
+					  enum rtmutex_chainwalk chwalk)
+{
+	/*
+	 * This is just a wrapper function for the following call,
+	 * because debug_rt_mutex_detect_deadlock() smells like a magic
+	 * debug feature and I wanted to keep the cond function in the
+	 * main source file along with the comments instead of having
+	 * two of the same in the headers.
+	 */
+	return debug_rt_mutex_detect_deadlock(waiter, chwalk);
+}
+
+/*
+ * Max number of times we'll walk the boosting chain:
+ */
+int max_lock_depth = 1024;
+
+static inline struct rt_mutex *task_blocked_on_lock(struct task_struct *p)
+{
+	return p->pi_blocked_on ? p->pi_blocked_on->lock : NULL;
+}
+
+/*
+ * Adjust the priority chain. Also used for deadlock detection.
+ * Decreases task's usage by one - may thus free the task.
+ *
+ * @task:	the task owning the mutex (owner) for which a chain walk is
+ *		probably needed
+ * @chwalk:	do we have to carry out deadlock detection?
+ * @orig_lock:	the mutex (can be NULL if we are walking the chain to recheck
+ *		things for a task that has just got its priority adjusted, and
+ *		is waiting on a mutex)
+ * @next_lock:	the mutex on which the owner of @orig_lock was blocked before
+ *		we dropped its pi_lock. Is never dereferenced, only used for
+ *		comparison to detect lock chain changes.
+ * @orig_waiter: rt_mutex_waiter struct for the task that has just donated
+ *		its priority to the mutex owner (can be NULL in the case
+ *		depicted above or if the top waiter is gone away and we are
+ *		actually deboosting the owner)
+ * @top_task:	the current top waiter
+ *
+ * Returns 0 or -EDEADLK.
+ *
+ * Chain walk basics and protection scope
+ *
+ * [R] refcount on task
+ * [P] task->pi_lock held
+ * [L] rtmutex->wait_lock held
+ *
+ * Step	Description				Protected by
+ *	function arguments:
+ *	@task					[R]
+ *	@orig_lock if != NULL			@top_task is blocked on it
+ *	@next_lock				Unprotected. Cannot be
+ *						dereferenced. Only used for
+ *						comparison.
+ *	@orig_waiter if != NULL			@top_task is blocked on it
+ *	@top_task				current, or in case of proxy
+ *						locking protected by calling
+ *						code
+ *	again:
+ *	  loop_sanity_check();
+ *	retry:
+ * [1]	  lock(task->pi_lock);			[R] acquire [P]
+ * [2]	  waiter = task->pi_blocked_on;		[P]
+ * [3]	  check_exit_conditions_1();		[P]
+ * [4]	  lock = waiter->lock;			[P]
+ * [5]	  if (!try_lock(lock->wait_lock)) {	[P] try to acquire [L]
+ *	    unlock(task->pi_lock);		release [P]
+ *	    goto retry;
+ *	  }
+ * [6]	  check_exit_conditions_2();		[P] + [L]
+ * [7]	  requeue_lock_waiter(lock, waiter);	[P] + [L]
+ * [8]	  unlock(task->pi_lock);		release [P]
+ *	  put_task_struct(task);		release [R]
+ * [9]	  check_exit_conditions_3();		[L]
+ * [10]	  task = owner(lock);			[L]
+ *	  get_task_struct(task);		[L] acquire [R]
+ *	  lock(task->pi_lock);			[L] acquire [P]
+ * [11]	  requeue_pi_waiter(tsk, waiters(lock));[P] + [L]
+ * [12]	  check_exit_conditions_4();		[P] + [L]
+ * [13]	  unlock(task->pi_lock);		release [P]
+ *	  unlock(lock->wait_lock);		release [L]
+ *	  goto again;
+ */
+static int rt_mutex_adjust_prio_chain(struct task_struct *task,
+				      enum rtmutex_chainwalk chwalk,
+				      struct rt_mutex *orig_lock,
+				      struct rt_mutex *next_lock,
+				      struct rt_mutex_waiter *orig_waiter,
+				      struct task_struct *top_task)
+{
+	struct rt_mutex_waiter *waiter, *top_waiter = orig_waiter;
+	struct rt_mutex_waiter *prerequeue_top_waiter;
+	int ret = 0, depth = 0;
+	struct rt_mutex *lock;
+	bool detect_deadlock;
+	unsigned long flags;
+	bool requeue = true;
+
+	detect_deadlock = rt_mutex_cond_detect_deadlock(orig_waiter, chwalk);
+
+	/*
+	 * The (de)boosting is a step by step approach with a lot of
+	 * pitfalls. We want this to be preemptible and we want hold a
+	 * maximum of two locks per step. So we have to check
+	 * carefully whether things change under us.
+	 */
+ again:
+	/*
+	 * We limit the lock chain length for each invocation.
+	 */
+	if (++depth > max_lock_depth) {
+		static int prev_max;
+
+		/*
+		 * Print this only once. If the admin changes the limit,
+		 * print a new message when reaching the limit again.
+		 */
+		if (prev_max != max_lock_depth) {
+			prev_max = max_lock_depth;
+			printk(KERN_WARNING "Maximum lock depth %d reached "
+			       "task: %s (%d)\n", max_lock_depth,
+			       top_task->comm, task_pid_nr(top_task));
+		}
+		put_task_struct(task);
+
+		return -EDEADLK;
+	}
+
+	/*
+	 * We are fully preemptible here and only hold the refcount on
+	 * @task. So everything can have changed under us since the
+	 * caller or our own code below (goto retry/again) dropped all
+	 * locks.
+	 */
+ retry:
+	/*
+	 * [1] Task cannot go away as we did a get_task() before !
+	 */
+	raw_spin_lock_irqsave(&task->pi_lock, flags);
+
+	/*
+	 * [2] Get the waiter on which @task is blocked on.
+	 */
+	waiter = task->pi_blocked_on;
+
+	/*
+	 * [3] check_exit_conditions_1() protected by task->pi_lock.
+	 */
+
+	/*
+	 * Check whether the end of the boosting chain has been
+	 * reached or the state of the chain has changed while we
+	 * dropped the locks.
+	 */
+	if (!waiter)
+		goto out_unlock_pi;
+
+	/*
+	 * Check the orig_waiter state. After we dropped the locks,
+	 * the previous owner of the lock might have released the lock.
+	 */
+	if (orig_waiter && !rt_mutex_owner(orig_lock))
+		goto out_unlock_pi;
+
+	/*
+	 * We dropped all locks after taking a refcount on @task, so
+	 * the task might have moved on in the lock chain or even left
+	 * the chain completely and blocks now on an unrelated lock or
+	 * on @orig_lock.
+	 *
+	 * We stored the lock on which @task was blocked in @next_lock,
+	 * so we can detect the chain change.
+	 */
+	if (next_lock != waiter->lock)
+		goto out_unlock_pi;
+
+	/*
+	 * Drop out, when the task has no waiters. Note,
+	 * top_waiter can be NULL, when we are in the deboosting
+	 * mode!
+	 */
+	if (top_waiter) {
+		if (!task_has_pi_waiters(task))
+			goto out_unlock_pi;
+		/*
+		 * If deadlock detection is off, we stop here if we
+		 * are not the top pi waiter of the task. If deadlock
+		 * detection is enabled we continue, but stop the
+		 * requeueing in the chain walk.
+		 */
+		if (top_waiter != task_top_pi_waiter(task)) {
+			if (!detect_deadlock)
+				goto out_unlock_pi;
+			else
+				requeue = false;
+		}
+	}
+
+	/*
+	 * If the waiter priority is the same as the task priority
+	 * then there is no further priority adjustment necessary.  If
+	 * deadlock detection is off, we stop the chain walk. If its
+	 * enabled we continue, but stop the requeueing in the chain
+	 * walk.
+	 */
+	if (waiter->prio == task->prio) {
+		if (!detect_deadlock)
+			goto out_unlock_pi;
+		else
+			requeue = false;
+	}
+
+	/*
+	 * [4] Get the next lock
+	 */
+	lock = waiter->lock;
+	/*
+	 * [5] We need to trylock here as we are holding task->pi_lock,
+	 * which is the reverse lock order versus the other rtmutex
+	 * operations.
+	 */
+	if (!raw_spin_trylock(&lock->wait_lock)) {
+		raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+		cpu_relax();
+		goto retry;
+	}
+
+	/*
+	 * [6] check_exit_conditions_2() protected by task->pi_lock and
+	 * lock->wait_lock.
+	 *
+	 * Deadlock detection. If the lock is the same as the original
+	 * lock which caused us to walk the lock chain or if the
+	 * current lock is owned by the task which initiated the chain
+	 * walk, we detected a deadlock.
+	 */
+	if (lock == orig_lock || rt_mutex_owner(lock) == top_task) {
+		debug_rt_mutex_deadlock(chwalk, orig_waiter, lock);
+		raw_spin_unlock(&lock->wait_lock);
+		ret = -EDEADLK;
+		goto out_unlock_pi;
+	}
+
+	/*
+	 * If we just follow the lock chain for deadlock detection, no
+	 * need to do all the requeue operations. To avoid a truckload
+	 * of conditionals around the various places below, just do the
+	 * minimum chain walk checks.
+	 */
+	if (!requeue) {
+		/*
+		 * No requeue[7] here. Just release @task [8]
+		 */
+		raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+		put_task_struct(task);
+
+		/*
+		 * [9] check_exit_conditions_3 protected by lock->wait_lock.
+		 * If there is no owner of the lock, end of chain.
+		 */
+		if (!rt_mutex_owner(lock)) {
+			raw_spin_unlock(&lock->wait_lock);
+			return 0;
+		}
+
+		/* [10] Grab the next task, i.e. owner of @lock */
+		task = rt_mutex_owner(lock);
+		get_task_struct(task);
+		raw_spin_lock_irqsave(&task->pi_lock, flags);
+
+		/*
+		 * No requeue [11] here. We just do deadlock detection.
+		 *
+		 * [12] Store whether owner is blocked
+		 * itself. Decision is made after dropping the locks
+		 */
+		next_lock = task_blocked_on_lock(task);
+		/*
+		 * Get the top waiter for the next iteration
+		 */
+		top_waiter = rt_mutex_top_waiter(lock);
+
+		/* [13] Drop locks */
+		raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+		raw_spin_unlock(&lock->wait_lock);
+
+		/* If owner is not blocked, end of chain. */
+		if (!next_lock)
+			goto out_put_task;
+		goto again;
+	}
+
+	/*
+	 * Store the current top waiter before doing the requeue
+	 * operation on @lock. We need it for the boost/deboost
+	 * decision below.
+	 */
+	prerequeue_top_waiter = rt_mutex_top_waiter(lock);
+
+	/* [7] Requeue the waiter in the lock waiter list. */
+	rt_mutex_dequeue(lock, waiter);
+	waiter->prio = task->prio;
+	rt_mutex_enqueue(lock, waiter);
+
+	/* [8] Release the task */
+	raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+	put_task_struct(task);
+
+	/*
+	 * [9] check_exit_conditions_3 protected by lock->wait_lock.
+	 *
+	 * We must abort the chain walk if there is no lock owner even
+	 * in the dead lock detection case, as we have nothing to
+	 * follow here. This is the end of the chain we are walking.
+	 */
+	if (!rt_mutex_owner(lock)) {
+		/*
+		 * If the requeue [7] above changed the top waiter,
+		 * then we need to wake the new top waiter up to try
+		 * to get the lock.
+		 */
+		if (prerequeue_top_waiter != rt_mutex_top_waiter(lock))
+			wake_up_process(rt_mutex_top_waiter(lock)->task);
+		raw_spin_unlock(&lock->wait_lock);
+		return 0;
+	}
+
+	/* [10] Grab the next task, i.e. the owner of @lock */
+	task = rt_mutex_owner(lock);
+	get_task_struct(task);
+	raw_spin_lock_irqsave(&task->pi_lock, flags);
+
+	/* [11] requeue the pi waiters if necessary */
+	if (waiter == rt_mutex_top_waiter(lock)) {
+		/*
+		 * The waiter became the new top (highest priority)
+		 * waiter on the lock. Replace the previous top waiter
+		 * in the owner tasks pi waiters list with this waiter
+		 * and adjust the priority of the owner.
+		 */
+		rt_mutex_dequeue_pi(task, prerequeue_top_waiter);
+		rt_mutex_enqueue_pi(task, waiter);
+		__rt_mutex_adjust_prio(task);
+
+	} else if (prerequeue_top_waiter == waiter) {
+		/*
+		 * The waiter was the top waiter on the lock, but is
+		 * no longer the top prority waiter. Replace waiter in
+		 * the owner tasks pi waiters list with the new top
+		 * (highest priority) waiter and adjust the priority
+		 * of the owner.
+		 * The new top waiter is stored in @waiter so that
+		 * @waiter == @top_waiter evaluates to true below and
+		 * we continue to deboost the rest of the chain.
+		 */
+		rt_mutex_dequeue_pi(task, waiter);
+		waiter = rt_mutex_top_waiter(lock);
+		rt_mutex_enqueue_pi(task, waiter);
+		__rt_mutex_adjust_prio(task);
+	} else {
+		/*
+		 * Nothing changed. No need to do any priority
+		 * adjustment.
+		 */
+	}
+
+	/*
+	 * [12] check_exit_conditions_4() protected by task->pi_lock
+	 * and lock->wait_lock. The actual decisions are made after we
+	 * dropped the locks.
+	 *
+	 * Check whether the task which owns the current lock is pi
+	 * blocked itself. If yes we store a pointer to the lock for
+	 * the lock chain change detection above. After we dropped
+	 * task->pi_lock next_lock cannot be dereferenced anymore.
+	 */
+	next_lock = task_blocked_on_lock(task);
+	/*
+	 * Store the top waiter of @lock for the end of chain walk
+	 * decision below.
+	 */
+	top_waiter = rt_mutex_top_waiter(lock);
+
+	/* [13] Drop the locks */
+	raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+	raw_spin_unlock(&lock->wait_lock);
+
+	/*
+	 * Make the actual exit decisions [12], based on the stored
+	 * values.
+	 *
+	 * We reached the end of the lock chain. Stop right here. No
+	 * point to go back just to figure that out.
+	 */
+	if (!next_lock)
+		goto out_put_task;
+
+	/*
+	 * If the current waiter is not the top waiter on the lock,
+	 * then we can stop the chain walk here if we are not in full
+	 * deadlock detection mode.
+	 */
+	if (!detect_deadlock && waiter != top_waiter)
+		goto out_put_task;
+
+	goto again;
+
+ out_unlock_pi:
+	raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+ out_put_task:
+	put_task_struct(task);
+
+	return ret;
+}
+
+/*
+ * Try to take an rt-mutex
+ *
+ * Must be called with lock->wait_lock held.
+ *
+ * @lock:   The lock to be acquired.
+ * @task:   The task which wants to acquire the lock
+ * @waiter: The waiter that is queued to the lock's wait list if the
+ *	    callsite called task_blocked_on_lock(), otherwise NULL
+ */
+static int try_to_take_rt_mutex(struct rt_mutex *lock, struct task_struct *task,
+				struct rt_mutex_waiter *waiter)
+{
+	unsigned long flags;
+
+	/*
+	 * Before testing whether we can acquire @lock, we set the
+	 * RT_MUTEX_HAS_WAITERS bit in @lock->owner. This forces all
+	 * other tasks which try to modify @lock into the slow path
+	 * and they serialize on @lock->wait_lock.
+	 *
+	 * The RT_MUTEX_HAS_WAITERS bit can have a transitional state
+	 * as explained at the top of this file if and only if:
+	 *
+	 * - There is a lock owner. The caller must fixup the
+	 *   transient state if it does a trylock or leaves the lock
+	 *   function due to a signal or timeout.
+	 *
+	 * - @task acquires the lock and there are no other
+	 *   waiters. This is undone in rt_mutex_set_owner(@task) at
+	 *   the end of this function.
+	 */
+	mark_rt_mutex_waiters(lock);
+
+	/*
+	 * If @lock has an owner, give up.
+	 */
+	if (rt_mutex_owner(lock))
+		return 0;
+
+	/*
+	 * If @waiter != NULL, @task has already enqueued the waiter
+	 * into @lock waiter list. If @waiter == NULL then this is a
+	 * trylock attempt.
+	 */
+	if (waiter) {
+		/*
+		 * If waiter is not the highest priority waiter of
+		 * @lock, give up.
+		 */
+		if (waiter != rt_mutex_top_waiter(lock))
+			return 0;
+
+		/*
+		 * We can acquire the lock. Remove the waiter from the
+		 * lock waiters list.
+		 */
+		rt_mutex_dequeue(lock, waiter);
+
+	} else {
+		/*
+		 * If the lock has waiters already we check whether @task is
+		 * eligible to take over the lock.
+		 *
+		 * If there are no other waiters, @task can acquire
+		 * the lock.  @task->pi_blocked_on is NULL, so it does
+		 * not need to be dequeued.
+		 */
+		if (rt_mutex_has_waiters(lock)) {
+			/*
+			 * If @task->prio is greater than or equal to
+			 * the top waiter priority (kernel view),
+			 * @task lost.
+			 */
+			if (task->prio >= rt_mutex_top_waiter(lock)->prio)
+				return 0;
+
+			/*
+			 * The current top waiter stays enqueued. We
+			 * don't have to change anything in the lock
+			 * waiters order.
+			 */
+		} else {
+			/*
+			 * No waiters. Take the lock without the
+			 * pi_lock dance.@task->pi_blocked_on is NULL
+			 * and we have no waiters to enqueue in @task
+			 * pi waiters list.
+			 */
+			goto takeit;
+		}
+	}
+
+	/*
+	 * Clear @task->pi_blocked_on. Requires protection by
+	 * @task->pi_lock. Redundant operation for the @waiter == NULL
+	 * case, but conditionals are more expensive than a redundant
+	 * store.
+	 */
+	raw_spin_lock_irqsave(&task->pi_lock, flags);
+	task->pi_blocked_on = NULL;
+	/*
+	 * Finish the lock acquisition. @task is the new owner. If
+	 * other waiters exist we have to insert the highest priority
+	 * waiter into @task->pi_waiters list.
+	 */
+	if (rt_mutex_has_waiters(lock))
+		rt_mutex_enqueue_pi(task, rt_mutex_top_waiter(lock));
+	raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+
+takeit:
+	/* We got the lock. */
+	debug_rt_mutex_lock(lock);
+
+	/*
+	 * This either preserves the RT_MUTEX_HAS_WAITERS bit if there
+	 * are still waiters or clears it.
+	 */
+	rt_mutex_set_owner(lock, task);
+
+	rt_mutex_deadlock_account_lock(lock, task);
+
+	return 1;
+}
+
+/*
+ * Task blocks on lock.
+ *
+ * Prepare waiter and propagate pi chain
+ *
+ * This must be called with lock->wait_lock held.
+ */
+static int task_blocks_on_rt_mutex(struct rt_mutex *lock,
+				   struct rt_mutex_waiter *waiter,
+				   struct task_struct *task,
+				   enum rtmutex_chainwalk chwalk)
+{
+	struct task_struct *owner = rt_mutex_owner(lock);
+	struct rt_mutex_waiter *top_waiter = waiter;
+	struct rt_mutex *next_lock;
+	int chain_walk = 0, res;
+	unsigned long flags;
+
+	/*
+	 * Early deadlock detection. We really don't want the task to
+	 * enqueue on itself just to untangle the mess later. It's not
+	 * only an optimization. We drop the locks, so another waiter
+	 * can come in before the chain walk detects the deadlock. So
+	 * the other will detect the deadlock and return -EDEADLOCK,
+	 * which is wrong, as the other waiter is not in a deadlock
+	 * situation.
+	 */
+	if (owner == task)
+		return -EDEADLK;
+
+	raw_spin_lock_irqsave(&task->pi_lock, flags);
+	__rt_mutex_adjust_prio(task);
+	waiter->task = task;
+	waiter->lock = lock;
+	waiter->prio = task->prio;
+
+	/* Get the top priority waiter on the lock */
+	if (rt_mutex_has_waiters(lock))
+		top_waiter = rt_mutex_top_waiter(lock);
+	rt_mutex_enqueue(lock, waiter);
+
+	task->pi_blocked_on = waiter;
+
+	raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+
+	if (!owner)
+		return 0;
+
+	raw_spin_lock_irqsave(&owner->pi_lock, flags);
+	if (waiter == rt_mutex_top_waiter(lock)) {
+		rt_mutex_dequeue_pi(owner, top_waiter);
+		rt_mutex_enqueue_pi(owner, waiter);
+
+		__rt_mutex_adjust_prio(owner);
+		if (owner->pi_blocked_on)
+			chain_walk = 1;
+	} else if (rt_mutex_cond_detect_deadlock(waiter, chwalk)) {
+		chain_walk = 1;
+	}
+
+	/* Store the lock on which owner is blocked or NULL */
+	next_lock = task_blocked_on_lock(owner);
+
+	raw_spin_unlock_irqrestore(&owner->pi_lock, flags);
+	/*
+	 * Even if full deadlock detection is on, if the owner is not
+	 * blocked itself, we can avoid finding this out in the chain
+	 * walk.
+	 */
+	if (!chain_walk || !next_lock)
+		return 0;
+
+	/*
+	 * The owner can't disappear while holding a lock,
+	 * so the owner struct is protected by wait_lock.
+	 * Gets dropped in rt_mutex_adjust_prio_chain()!
+	 */
+	get_task_struct(owner);
+
+	raw_spin_unlock(&lock->wait_lock);
+
+	res = rt_mutex_adjust_prio_chain(owner, chwalk, lock,
+					 next_lock, waiter, task);
+
+	raw_spin_lock(&lock->wait_lock);
+
+	return res;
+}
+
+/*
+ * Wake up the next waiter on the lock.
+ *
+ * Remove the top waiter from the current tasks pi waiter list and
+ * wake it up.
+ *
+ * Called with lock->wait_lock held.
+ */
+static void wakeup_next_waiter(struct rt_mutex *lock)
+{
+	struct rt_mutex_waiter *waiter;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&current->pi_lock, flags);
+
+	waiter = rt_mutex_top_waiter(lock);
+
+	/*
+	 * Remove it from current->pi_waiters. We do not adjust a
+	 * possible priority boost right now. We execute wakeup in the
+	 * boosted mode and go back to normal after releasing
+	 * lock->wait_lock.
+	 */
+	rt_mutex_dequeue_pi(current, waiter);
+
+	/*
+	 * As we are waking up the top waiter, and the waiter stays
+	 * queued on the lock until it gets the lock, this lock
+	 * obviously has waiters. Just set the bit here and this has
+	 * the added benefit of forcing all new tasks into the
+	 * slow path making sure no task of lower priority than
+	 * the top waiter can steal this lock.
+	 */
+	lock->owner = (void *) RT_MUTEX_HAS_WAITERS;
+
+	raw_spin_unlock_irqrestore(&current->pi_lock, flags);
+
+	/*
+	 * It's safe to dereference waiter as it cannot go away as
+	 * long as we hold lock->wait_lock. The waiter task needs to
+	 * acquire it in order to dequeue the waiter.
+	 */
+	wake_up_process(waiter->task);
+}
+
+/*
+ * Remove a waiter from a lock and give up
+ *
+ * Must be called with lock->wait_lock held and
+ * have just failed to try_to_take_rt_mutex().
+ */
+static void remove_waiter(struct rt_mutex *lock,
+			  struct rt_mutex_waiter *waiter)
+{
+	bool is_top_waiter = (waiter == rt_mutex_top_waiter(lock));
+	struct task_struct *owner = rt_mutex_owner(lock);
+	struct rt_mutex *next_lock;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&current->pi_lock, flags);
+	rt_mutex_dequeue(lock, waiter);
+	current->pi_blocked_on = NULL;
+	raw_spin_unlock_irqrestore(&current->pi_lock, flags);
+
+	/*
+	 * Only update priority if the waiter was the highest priority
+	 * waiter of the lock and there is an owner to update.
+	 */
+	if (!owner || !is_top_waiter)
+		return;
+
+	raw_spin_lock_irqsave(&owner->pi_lock, flags);
+
+	rt_mutex_dequeue_pi(owner, waiter);
+
+	if (rt_mutex_has_waiters(lock))
+		rt_mutex_enqueue_pi(owner, rt_mutex_top_waiter(lock));
+
+	__rt_mutex_adjust_prio(owner);
+
+	/* Store the lock on which owner is blocked or NULL */
+	next_lock = task_blocked_on_lock(owner);
+
+	raw_spin_unlock_irqrestore(&owner->pi_lock, flags);
+
+	/*
+	 * Don't walk the chain, if the owner task is not blocked
+	 * itself.
+	 */
+	if (!next_lock)
+		return;
+
+	/* gets dropped in rt_mutex_adjust_prio_chain()! */
+	get_task_struct(owner);
+
+	raw_spin_unlock(&lock->wait_lock);
+
+	rt_mutex_adjust_prio_chain(owner, RT_MUTEX_MIN_CHAINWALK, lock,
+				   next_lock, NULL, current);
+
+	raw_spin_lock(&lock->wait_lock);
+}
+
+/*
+ * Recheck the pi chain, in case we got a priority setting
+ *
+ * Called from sched_setscheduler
+ */
+void rt_mutex_adjust_pi(struct task_struct *task)
+{
+	struct rt_mutex_waiter *waiter;
+	struct rt_mutex *next_lock;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&task->pi_lock, flags);
+
+	waiter = task->pi_blocked_on;
+	if (!waiter || (waiter->prio == task->prio &&
+			!dl_prio(task->prio))) {
+		raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+		return;
+	}
+	next_lock = waiter->lock;
+	raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+
+	/* gets dropped in rt_mutex_adjust_prio_chain()! */
+	get_task_struct(task);
+
+	rt_mutex_adjust_prio_chain(task, RT_MUTEX_MIN_CHAINWALK, NULL,
+				   next_lock, NULL, task);
+}
+
+/**
+ * __rt_mutex_slowlock() - Perform the wait-wake-try-to-take loop
+ * @lock:		 the rt_mutex to take
+ * @state:		 the state the task should block in (TASK_INTERRUPTIBLE
+ * 			 or TASK_UNINTERRUPTIBLE)
+ * @timeout:		 the pre-initialized and started timer, or NULL for none
+ * @waiter:		 the pre-initialized rt_mutex_waiter
+ *
+ * lock->wait_lock must be held by the caller.
+ */
+static int __sched
+__rt_mutex_slowlock(struct rt_mutex *lock, int state,
+		    struct hrtimer_sleeper *timeout,
+		    struct rt_mutex_waiter *waiter)
+{
+	int ret = 0;
+
+	for (;;) {
+		/* Try to acquire the lock: */
+		if (try_to_take_rt_mutex(lock, current, waiter))
+			break;
+
+		/*
+		 * TASK_INTERRUPTIBLE checks for signals and
+		 * timeout. Ignored otherwise.
+		 */
+		if (unlikely(state == TASK_INTERRUPTIBLE)) {
+			/* Signal pending? */
+			if (signal_pending(current))
+				ret = -EINTR;
+			if (timeout && !timeout->task)
+				ret = -ETIMEDOUT;
+			if (ret)
+				break;
+		}
+
+		raw_spin_unlock(&lock->wait_lock);
+
+		debug_rt_mutex_print_deadlock(waiter);
+
+		schedule_rt_mutex(lock);
+
+		raw_spin_lock(&lock->wait_lock);
+		set_current_state(state);
+	}
+
+	__set_current_state(TASK_RUNNING);
+	return ret;
+}
+
+static void rt_mutex_handle_deadlock(int res, int detect_deadlock,
+				     struct rt_mutex_waiter *w)
+{
+	/*
+	 * If the result is not -EDEADLOCK or the caller requested
+	 * deadlock detection, nothing to do here.
+	 */
+	if (res != -EDEADLOCK || detect_deadlock)
+		return;
+
+	/*
+	 * Yell lowdly and stop the task right here.
+	 */
+	rt_mutex_print_deadlock(w);
+	while (1) {
+		set_current_state(TASK_INTERRUPTIBLE);
+		schedule();
+	}
+}
+
+/*
+ * Slow path lock function:
+ */
+static int __sched
+rt_mutex_slowlock(struct rt_mutex *lock, int state,
+		  struct hrtimer_sleeper *timeout,
+		  enum rtmutex_chainwalk chwalk)
+{
+	struct rt_mutex_waiter waiter;
+	int ret = 0;
+
+	debug_rt_mutex_init_waiter(&waiter);
+	RB_CLEAR_NODE(&waiter.pi_tree_entry);
+	RB_CLEAR_NODE(&waiter.tree_entry);
+
+	raw_spin_lock(&lock->wait_lock);
+
+	/* Try to acquire the lock again: */
+	if (try_to_take_rt_mutex(lock, current, NULL)) {
+		raw_spin_unlock(&lock->wait_lock);
+		return 0;
+	}
+
+	set_current_state(state);
+
+	/* Setup the timer, when timeout != NULL */
+	if (unlikely(timeout)) {
+		hrtimer_start_expires(&timeout->timer, HRTIMER_MODE_ABS);
+		if (!hrtimer_active(&timeout->timer))
+			timeout->task = NULL;
+	}
+
+	ret = task_blocks_on_rt_mutex(lock, &waiter, current, chwalk);
+
+	if (likely(!ret))
+		/* sleep on the mutex */
+		ret = __rt_mutex_slowlock(lock, state, timeout, &waiter);
+
+	if (unlikely(ret)) {
+		__set_current_state(TASK_RUNNING);
+		if (rt_mutex_has_waiters(lock))
+			remove_waiter(lock, &waiter);
+		rt_mutex_handle_deadlock(ret, chwalk, &waiter);
+	}
+
+	/*
+	 * try_to_take_rt_mutex() sets the waiter bit
+	 * unconditionally. We might have to fix that up.
+	 */
+	fixup_rt_mutex_waiters(lock);
+
+	raw_spin_unlock(&lock->wait_lock);
+
+	/* Remove pending timer: */
+	if (unlikely(timeout))
+		hrtimer_cancel(&timeout->timer);
+
+	debug_rt_mutex_free_waiter(&waiter);
+
+	return ret;
+}
+
+/*
+ * Slow path try-lock function:
+ */
+static inline int rt_mutex_slowtrylock(struct rt_mutex *lock)
+{
+	int ret;
+
+	/*
+	 * If the lock already has an owner we fail to get the lock.
+	 * This can be done without taking the @lock->wait_lock as
+	 * it is only being read, and this is a trylock anyway.
+	 */
+	if (rt_mutex_owner(lock))
+		return 0;
+
+	/*
+	 * The mutex has currently no owner. Lock the wait lock and
+	 * try to acquire the lock.
+	 */
+	raw_spin_lock(&lock->wait_lock);
+
+	ret = try_to_take_rt_mutex(lock, current, NULL);
+
+	/*
+	 * try_to_take_rt_mutex() sets the lock waiters bit
+	 * unconditionally. Clean this up.
+	 */
+	fixup_rt_mutex_waiters(lock);
+
+	raw_spin_unlock(&lock->wait_lock);
+
+	return ret;
+}
+
+/*
+ * Slow path to release a rt-mutex:
+ */
+static void __sched
+rt_mutex_slowunlock(struct rt_mutex *lock)
+{
+	raw_spin_lock(&lock->wait_lock);
+
+	debug_rt_mutex_unlock(lock);
+
+	rt_mutex_deadlock_account_unlock(current);
+
+	/*
+	 * We must be careful here if the fast path is enabled. If we
+	 * have no waiters queued we cannot set owner to NULL here
+	 * because of:
+	 *
+	 * foo->lock->owner = NULL;
+	 *			rtmutex_lock(foo->lock);   <- fast path
+	 *			free = atomic_dec_and_test(foo->refcnt);
+	 *			rtmutex_unlock(foo->lock); <- fast path
+	 *			if (free)
+	 *				kfree(foo);
+	 * raw_spin_unlock(foo->lock->wait_lock);
+	 *
+	 * So for the fastpath enabled kernel:
+	 *
+	 * Nothing can set the waiters bit as long as we hold
+	 * lock->wait_lock. So we do the following sequence:
+	 *
+	 *	owner = rt_mutex_owner(lock);
+	 *	clear_rt_mutex_waiters(lock);
+	 *	raw_spin_unlock(&lock->wait_lock);
+	 *	if (cmpxchg(&lock->owner, owner, 0) == owner)
+	 *		return;
+	 *	goto retry;
+	 *
+	 * The fastpath disabled variant is simple as all access to
+	 * lock->owner is serialized by lock->wait_lock:
+	 *
+	 *	lock->owner = NULL;
+	 *	raw_spin_unlock(&lock->wait_lock);
+	 */
+	while (!rt_mutex_has_waiters(lock)) {
+		/* Drops lock->wait_lock ! */
+		if (unlock_rt_mutex_safe(lock) == true)
+			return;
+		/* Relock the rtmutex and try again */
+		raw_spin_lock(&lock->wait_lock);
+	}
+
+	/*
+	 * The wakeup next waiter path does not suffer from the above
+	 * race. See the comments there.
+	 */
+	wakeup_next_waiter(lock);
+
+	raw_spin_unlock(&lock->wait_lock);
+
+	/* Undo pi boosting if necessary: */
+	rt_mutex_adjust_prio(current);
+}
+
+/*
+ * debug aware fast / slowpath lock,trylock,unlock
+ *
+ * The atomic acquire/release ops are compiled away, when either the
+ * architecture does not support cmpxchg or when debugging is enabled.
+ */
+static inline int
+rt_mutex_fastlock(struct rt_mutex *lock, int state,
+		  int (*slowfn)(struct rt_mutex *lock, int state,
+				struct hrtimer_sleeper *timeout,
+				enum rtmutex_chainwalk chwalk))
+{
+	if (likely(rt_mutex_cmpxchg(lock, NULL, current))) {
+		rt_mutex_deadlock_account_lock(lock, current);
+		return 0;
+	} else
+		return slowfn(lock, state, NULL, RT_MUTEX_MIN_CHAINWALK);
+}
+
+static inline int
+rt_mutex_timed_fastlock(struct rt_mutex *lock, int state,
+			struct hrtimer_sleeper *timeout,
+			enum rtmutex_chainwalk chwalk,
+			int (*slowfn)(struct rt_mutex *lock, int state,
+				      struct hrtimer_sleeper *timeout,
+				      enum rtmutex_chainwalk chwalk))
+{
+	if (chwalk == RT_MUTEX_MIN_CHAINWALK &&
+	    likely(rt_mutex_cmpxchg(lock, NULL, current))) {
+		rt_mutex_deadlock_account_lock(lock, current);
+		return 0;
+	} else
+		return slowfn(lock, state, timeout, chwalk);
+}
+
+static inline int
+rt_mutex_fasttrylock(struct rt_mutex *lock,
+		     int (*slowfn)(struct rt_mutex *lock))
+{
+	if (likely(rt_mutex_cmpxchg(lock, NULL, current))) {
+		rt_mutex_deadlock_account_lock(lock, current);
+		return 1;
+	}
+	return slowfn(lock);
+}
+
+static inline void
+rt_mutex_fastunlock(struct rt_mutex *lock,
+		    void (*slowfn)(struct rt_mutex *lock))
+{
+	if (likely(rt_mutex_cmpxchg(lock, current, NULL)))
+		rt_mutex_deadlock_account_unlock(current);
+	else
+		slowfn(lock);
+}
+
+/**
+ * rt_mutex_lock - lock a rt_mutex
+ *
+ * @lock: the rt_mutex to be locked
+ */
+void __sched rt_mutex_lock(struct rt_mutex *lock)
+{
+	might_sleep();
+
+	rt_mutex_fastlock(lock, TASK_UNINTERRUPTIBLE, rt_mutex_slowlock);
+}
+EXPORT_SYMBOL_GPL(rt_mutex_lock);
+
+/**
+ * rt_mutex_lock_interruptible - lock a rt_mutex interruptible
+ *
+ * @lock:		the rt_mutex to be locked
+ *
+ * Returns:
+ *  0		on success
+ * -EINTR	when interrupted by a signal
+ */
+int __sched rt_mutex_lock_interruptible(struct rt_mutex *lock)
+{
+	might_sleep();
+
+	return rt_mutex_fastlock(lock, TASK_INTERRUPTIBLE, rt_mutex_slowlock);
+}
+EXPORT_SYMBOL_GPL(rt_mutex_lock_interruptible);
+
+/*
+ * Futex variant with full deadlock detection.
+ */
+int rt_mutex_timed_futex_lock(struct rt_mutex *lock,
+			      struct hrtimer_sleeper *timeout)
+{
+	might_sleep();
+
+	return rt_mutex_timed_fastlock(lock, TASK_INTERRUPTIBLE, timeout,
+				       RT_MUTEX_FULL_CHAINWALK,
+				       rt_mutex_slowlock);
+}
+
+/**
+ * rt_mutex_timed_lock - lock a rt_mutex interruptible
+ *			the timeout structure is provided
+ *			by the caller
+ *
+ * @lock:		the rt_mutex to be locked
+ * @timeout:		timeout structure or NULL (no timeout)
+ *
+ * Returns:
+ *  0		on success
+ * -EINTR	when interrupted by a signal
+ * -ETIMEDOUT	when the timeout expired
+ */
+int
+rt_mutex_timed_lock(struct rt_mutex *lock, struct hrtimer_sleeper *timeout)
+{
+	might_sleep();
+
+	return rt_mutex_timed_fastlock(lock, TASK_INTERRUPTIBLE, timeout,
+				       RT_MUTEX_MIN_CHAINWALK,
+				       rt_mutex_slowlock);
+}
+EXPORT_SYMBOL_GPL(rt_mutex_timed_lock);
+
+/**
+ * rt_mutex_trylock - try to lock a rt_mutex
+ *
+ * @lock:	the rt_mutex to be locked
+ *
+ * Returns 1 on success and 0 on contention
+ */
+int __sched rt_mutex_trylock(struct rt_mutex *lock)
+{
+	return rt_mutex_fasttrylock(lock, rt_mutex_slowtrylock);
+}
+EXPORT_SYMBOL_GPL(rt_mutex_trylock);
+
+/**
+ * rt_mutex_unlock - unlock a rt_mutex
+ *
+ * @lock: the rt_mutex to be unlocked
+ */
+void __sched rt_mutex_unlock(struct rt_mutex *lock)
+{
+	rt_mutex_fastunlock(lock, rt_mutex_slowunlock);
+}
+EXPORT_SYMBOL_GPL(rt_mutex_unlock);
+
+/**
+ * rt_mutex_destroy - mark a mutex unusable
+ * @lock: the mutex to be destroyed
+ *
+ * This function marks the mutex uninitialized, and any subsequent
+ * use of the mutex is forbidden. The mutex must not be locked when
+ * this function is called.
+ */
+void rt_mutex_destroy(struct rt_mutex *lock)
+{
+	WARN_ON(rt_mutex_is_locked(lock));
+#ifdef CONFIG_DEBUG_RT_MUTEXES
+	lock->magic = NULL;
+#endif
+}
+
+EXPORT_SYMBOL_GPL(rt_mutex_destroy);
+
+/**
+ * __rt_mutex_init - initialize the rt lock
+ *
+ * @lock: the rt lock to be initialized
+ *
+ * Initialize the rt lock to unlocked state.
+ *
+ * Initializing of a locked rt lock is not allowed
+ */
+void __rt_mutex_init(struct rt_mutex *lock, const char *name)
+{
+	lock->owner = NULL;
+	raw_spin_lock_init(&lock->wait_lock);
+	lock->waiters = RB_ROOT;
+	lock->waiters_leftmost = NULL;
+
+	debug_rt_mutex_init(lock, name);
+}
+EXPORT_SYMBOL_GPL(__rt_mutex_init);
+
+/**
+ * rt_mutex_init_proxy_locked - initialize and lock a rt_mutex on behalf of a
+ *				proxy owner
+ *
+ * @lock: 	the rt_mutex to be locked
+ * @proxy_owner:the task to set as owner
+ *
+ * No locking. Caller has to do serializing itself
+ * Special API call for PI-futex support
+ */
+void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
+				struct task_struct *proxy_owner)
+{
+	__rt_mutex_init(lock, NULL);
+	debug_rt_mutex_proxy_lock(lock, proxy_owner);
+	rt_mutex_set_owner(lock, proxy_owner);
+	rt_mutex_deadlock_account_lock(lock, proxy_owner);
+}
+
+/**
+ * rt_mutex_proxy_unlock - release a lock on behalf of owner
+ *
+ * @lock: 	the rt_mutex to be locked
+ *
+ * No locking. Caller has to do serializing itself
+ * Special API call for PI-futex support
+ */
+void rt_mutex_proxy_unlock(struct rt_mutex *lock,
+			   struct task_struct *proxy_owner)
+{
+	debug_rt_mutex_proxy_unlock(lock);
+	rt_mutex_set_owner(lock, NULL);
+	rt_mutex_deadlock_account_unlock(proxy_owner);
+}
+
+/**
+ * rt_mutex_start_proxy_lock() - Start lock acquisition for another task
+ * @lock:		the rt_mutex to take
+ * @waiter:		the pre-initialized rt_mutex_waiter
+ * @task:		the task to prepare
+ *
+ * Returns:
+ *  0 - task blocked on lock
+ *  1 - acquired the lock for task, caller should wake it up
+ * <0 - error
+ *
+ * Special API call for FUTEX_REQUEUE_PI support.
+ */
+int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
+			      struct rt_mutex_waiter *waiter,
+			      struct task_struct *task)
+{
+	int ret;
+
+	raw_spin_lock(&lock->wait_lock);
+
+	if (try_to_take_rt_mutex(lock, task, NULL)) {
+		raw_spin_unlock(&lock->wait_lock);
+		return 1;
+	}
+
+	/* We enforce deadlock detection for futexes */
+	ret = task_blocks_on_rt_mutex(lock, waiter, task,
+				      RT_MUTEX_FULL_CHAINWALK);
+
+	if (ret && !rt_mutex_owner(lock)) {
+		/*
+		 * Reset the return value. We might have
+		 * returned with -EDEADLK and the owner
+		 * released the lock while we were walking the
+		 * pi chain.  Let the waiter sort it out.
+		 */
+		ret = 0;
+	}
+
+	if (unlikely(ret))
+		remove_waiter(lock, waiter);
+
+	raw_spin_unlock(&lock->wait_lock);
+
+	debug_rt_mutex_print_deadlock(waiter);
+
+	return ret;
+}
+
+/**
+ * rt_mutex_next_owner - return the next owner of the lock
+ *
+ * @lock: the rt lock query
+ *
+ * Returns the next owner of the lock or NULL
+ *
+ * Caller has to serialize against other accessors to the lock
+ * itself.
+ *
+ * Special API call for PI-futex support
+ */
+struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock)
+{
+	if (!rt_mutex_has_waiters(lock))
+		return NULL;
+
+	return rt_mutex_top_waiter(lock)->task;
+}
+
+/**
+ * rt_mutex_finish_proxy_lock() - Complete lock acquisition
+ * @lock:		the rt_mutex we were woken on
+ * @to:			the timeout, null if none. hrtimer should already have
+ *			been started.
+ * @waiter:		the pre-initialized rt_mutex_waiter
+ *
+ * Complete the lock acquisition started our behalf by another thread.
+ *
+ * Returns:
+ *  0 - success
+ * <0 - error, one of -EINTR, -ETIMEDOUT
+ *
+ * Special API call for PI-futex requeue support
+ */
+int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
+			       struct hrtimer_sleeper *to,
+			       struct rt_mutex_waiter *waiter)
+{
+	int ret;
+
+	raw_spin_lock(&lock->wait_lock);
+
+	set_current_state(TASK_INTERRUPTIBLE);
+
+	/* sleep on the mutex */
+	ret = __rt_mutex_slowlock(lock, TASK_INTERRUPTIBLE, to, waiter);
+
+	if (unlikely(ret))
+		remove_waiter(lock, waiter);
+
+	/*
+	 * try_to_take_rt_mutex() sets the waiter bit unconditionally. We might
+	 * have to fix that up.
+	 */
+	fixup_rt_mutex_waiters(lock);
+
+	raw_spin_unlock(&lock->wait_lock);
+
+	return ret;
+}
diff --git a/kernel/locking/rtmutex.h b/kernel/locking/rtmutex.h
new file mode 100644
index 000000000..c4060584c
--- /dev/null
+++ b/kernel/locking/rtmutex.h
@@ -0,0 +1,36 @@
+/*
+ * RT-Mutexes: blocking mutual exclusion locks with PI support
+ *
+ * started by Ingo Molnar and Thomas Gleixner:
+ *
+ *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *  Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
+ *
+ * This file contains macros used solely by rtmutex.c.
+ * Non-debug version.
+ */
+
+#define rt_mutex_deadlock_check(l)			(0)
+#define rt_mutex_deadlock_account_lock(m, t)		do { } while (0)
+#define rt_mutex_deadlock_account_unlock(l)		do { } while (0)
+#define debug_rt_mutex_init_waiter(w)			do { } while (0)
+#define debug_rt_mutex_free_waiter(w)			do { } while (0)
+#define debug_rt_mutex_lock(l)				do { } while (0)
+#define debug_rt_mutex_proxy_lock(l,p)			do { } while (0)
+#define debug_rt_mutex_proxy_unlock(l)			do { } while (0)
+#define debug_rt_mutex_unlock(l)			do { } while (0)
+#define debug_rt_mutex_init(m, n)			do { } while (0)
+#define debug_rt_mutex_deadlock(d, a ,l)		do { } while (0)
+#define debug_rt_mutex_print_deadlock(w)		do { } while (0)
+#define debug_rt_mutex_reset_waiter(w)			do { } while (0)
+
+static inline void rt_mutex_print_deadlock(struct rt_mutex_waiter *w)
+{
+	WARN(1, "rtmutex deadlock detected\n");
+}
+
+static inline bool debug_rt_mutex_detect_deadlock(struct rt_mutex_waiter *w,
+						  enum rtmutex_chainwalk walk)
+{
+	return walk == RT_MUTEX_FULL_CHAINWALK;
+}
diff --git a/kernel/locking/rtmutex_common.h b/kernel/locking/rtmutex_common.h
new file mode 100644
index 000000000..855212501
--- /dev/null
+++ b/kernel/locking/rtmutex_common.h
@@ -0,0 +1,141 @@
+/*
+ * RT Mutexes: blocking mutual exclusion locks with PI support
+ *
+ * started by Ingo Molnar and Thomas Gleixner:
+ *
+ *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *  Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
+ *
+ * This file contains the private data structure and API definitions.
+ */
+
+#ifndef __KERNEL_RTMUTEX_COMMON_H
+#define __KERNEL_RTMUTEX_COMMON_H
+
+#include <linux/rtmutex.h>
+
+/*
+ * The rtmutex in kernel tester is independent of rtmutex debugging. We
+ * call schedule_rt_mutex_test() instead of schedule() for the tasks which
+ * belong to the tester. That way we can delay the wakeup path of those
+ * threads to provoke lock stealing and testing of  complex boosting scenarios.
+ */
+#ifdef CONFIG_RT_MUTEX_TESTER
+
+extern void schedule_rt_mutex_test(struct rt_mutex *lock);
+
+#define schedule_rt_mutex(_lock)				\
+  do {								\
+	if (!(current->flags & PF_MUTEX_TESTER))		\
+		schedule();					\
+	else							\
+		schedule_rt_mutex_test(_lock);			\
+  } while (0)
+
+#else
+# define schedule_rt_mutex(_lock)			schedule()
+#endif
+
+/*
+ * This is the control structure for tasks blocked on a rt_mutex,
+ * which is allocated on the kernel stack on of the blocked task.
+ *
+ * @tree_entry:		pi node to enqueue into the mutex waiters tree
+ * @pi_tree_entry:	pi node to enqueue into the mutex owner waiters tree
+ * @task:		task reference to the blocked task
+ */
+struct rt_mutex_waiter {
+	struct rb_node          tree_entry;
+	struct rb_node          pi_tree_entry;
+	struct task_struct	*task;
+	struct rt_mutex		*lock;
+#ifdef CONFIG_DEBUG_RT_MUTEXES
+	unsigned long		ip;
+	struct pid		*deadlock_task_pid;
+	struct rt_mutex		*deadlock_lock;
+#endif
+	int prio;
+};
+
+/*
+ * Various helpers to access the waiters-tree:
+ */
+static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
+{
+	return !RB_EMPTY_ROOT(&lock->waiters);
+}
+
+static inline struct rt_mutex_waiter *
+rt_mutex_top_waiter(struct rt_mutex *lock)
+{
+	struct rt_mutex_waiter *w;
+
+	w = rb_entry(lock->waiters_leftmost, struct rt_mutex_waiter,
+		     tree_entry);
+	BUG_ON(w->lock != lock);
+
+	return w;
+}
+
+static inline int task_has_pi_waiters(struct task_struct *p)
+{
+	return !RB_EMPTY_ROOT(&p->pi_waiters);
+}
+
+static inline struct rt_mutex_waiter *
+task_top_pi_waiter(struct task_struct *p)
+{
+	return rb_entry(p->pi_waiters_leftmost, struct rt_mutex_waiter,
+			pi_tree_entry);
+}
+
+/*
+ * lock->owner state tracking:
+ */
+#define RT_MUTEX_HAS_WAITERS	1UL
+#define RT_MUTEX_OWNER_MASKALL	1UL
+
+static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
+{
+	return (struct task_struct *)
+		((unsigned long)lock->owner & ~RT_MUTEX_OWNER_MASKALL);
+}
+
+/*
+ * Constants for rt mutex functions which have a selectable deadlock
+ * detection.
+ *
+ * RT_MUTEX_MIN_CHAINWALK:	Stops the lock chain walk when there are
+ *				no further PI adjustments to be made.
+ *
+ * RT_MUTEX_FULL_CHAINWALK:	Invoke deadlock detection with a full
+ *				walk of the lock chain.
+ */
+enum rtmutex_chainwalk {
+	RT_MUTEX_MIN_CHAINWALK,
+	RT_MUTEX_FULL_CHAINWALK,
+};
+
+/*
+ * PI-futex support (proxy locking functions, etc.):
+ */
+extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
+extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
+				       struct task_struct *proxy_owner);
+extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
+				  struct task_struct *proxy_owner);
+extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
+				     struct rt_mutex_waiter *waiter,
+				     struct task_struct *task);
+extern int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
+				      struct hrtimer_sleeper *to,
+				      struct rt_mutex_waiter *waiter);
+extern int rt_mutex_timed_futex_lock(struct rt_mutex *l, struct hrtimer_sleeper *to);
+
+#ifdef CONFIG_DEBUG_RT_MUTEXES
+# include "rtmutex-debug.h"
+#else
+# include "rtmutex.h"
+#endif
+
+#endif
diff --git a/kernel/locking/rwsem-spinlock.c b/kernel/locking/rwsem-spinlock.c
new file mode 100644
index 000000000..3a5048572
--- /dev/null
+++ b/kernel/locking/rwsem-spinlock.c
@@ -0,0 +1,303 @@
+/* rwsem-spinlock.c: R/W semaphores: contention handling functions for
+ * generic spinlock implementation
+ *
+ * Copyright (c) 2001   David Howells (dhowells@redhat.com).
+ * - Derived partially from idea by Andrea Arcangeli <andrea@suse.de>
+ * - Derived also from comments by Linus
+ */
+#include <linux/rwsem.h>
+#include <linux/sched.h>
+#include <linux/export.h>
+
+enum rwsem_waiter_type {
+	RWSEM_WAITING_FOR_WRITE,
+	RWSEM_WAITING_FOR_READ
+};
+
+struct rwsem_waiter {
+	struct list_head list;
+	struct task_struct *task;
+	enum rwsem_waiter_type type;
+};
+
+int rwsem_is_locked(struct rw_semaphore *sem)
+{
+	int ret = 1;
+	unsigned long flags;
+
+	if (raw_spin_trylock_irqsave(&sem->wait_lock, flags)) {
+		ret = (sem->count != 0);
+		raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
+	}
+	return ret;
+}
+EXPORT_SYMBOL(rwsem_is_locked);
+
+/*
+ * initialise the semaphore
+ */
+void __init_rwsem(struct rw_semaphore *sem, const char *name,
+		  struct lock_class_key *key)
+{
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	/*
+	 * Make sure we are not reinitializing a held semaphore:
+	 */
+	debug_check_no_locks_freed((void *)sem, sizeof(*sem));
+	lockdep_init_map(&sem->dep_map, name, key, 0);
+#endif
+	sem->count = 0;
+	raw_spin_lock_init(&sem->wait_lock);
+	INIT_LIST_HEAD(&sem->wait_list);
+}
+EXPORT_SYMBOL(__init_rwsem);
+
+/*
+ * handle the lock release when processes blocked on it that can now run
+ * - if we come here, then:
+ *   - the 'active count' _reached_ zero
+ *   - the 'waiting count' is non-zero
+ * - the spinlock must be held by the caller
+ * - woken process blocks are discarded from the list after having task zeroed
+ * - writers are only woken if wakewrite is non-zero
+ */
+static inline struct rw_semaphore *
+__rwsem_do_wake(struct rw_semaphore *sem, int wakewrite)
+{
+	struct rwsem_waiter *waiter;
+	struct task_struct *tsk;
+	int woken;
+
+	waiter = list_entry(sem->wait_list.next, struct rwsem_waiter, list);
+
+	if (waiter->type == RWSEM_WAITING_FOR_WRITE) {
+		if (wakewrite)
+			/* Wake up a writer. Note that we do not grant it the
+			 * lock - it will have to acquire it when it runs. */
+			wake_up_process(waiter->task);
+		goto out;
+	}
+
+	/* grant an infinite number of read locks to the front of the queue */
+	woken = 0;
+	do {
+		struct list_head *next = waiter->list.next;
+
+		list_del(&waiter->list);
+		tsk = waiter->task;
+		/*
+		 * Make sure we do not wakeup the next reader before
+		 * setting the nil condition to grant the next reader;
+		 * otherwise we could miss the wakeup on the other
+		 * side and end up sleeping again. See the pairing
+		 * in rwsem_down_read_failed().
+		 */
+		smp_mb();
+		waiter->task = NULL;
+		wake_up_process(tsk);
+		put_task_struct(tsk);
+		woken++;
+		if (next == &sem->wait_list)
+			break;
+		waiter = list_entry(next, struct rwsem_waiter, list);
+	} while (waiter->type != RWSEM_WAITING_FOR_WRITE);
+
+	sem->count += woken;
+
+ out:
+	return sem;
+}
+
+/*
+ * wake a single writer
+ */
+static inline struct rw_semaphore *
+__rwsem_wake_one_writer(struct rw_semaphore *sem)
+{
+	struct rwsem_waiter *waiter;
+
+	waiter = list_entry(sem->wait_list.next, struct rwsem_waiter, list);
+	wake_up_process(waiter->task);
+
+	return sem;
+}
+
+/*
+ * get a read lock on the semaphore
+ */
+void __sched __down_read(struct rw_semaphore *sem)
+{
+	struct rwsem_waiter waiter;
+	struct task_struct *tsk;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&sem->wait_lock, flags);
+
+	if (sem->count >= 0 && list_empty(&sem->wait_list)) {
+		/* granted */
+		sem->count++;
+		raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
+		goto out;
+	}
+
+	tsk = current;
+	set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+
+	/* set up my own style of waitqueue */
+	waiter.task = tsk;
+	waiter.type = RWSEM_WAITING_FOR_READ;
+	get_task_struct(tsk);
+
+	list_add_tail(&waiter.list, &sem->wait_list);
+
+	/* we don't need to touch the semaphore struct anymore */
+	raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
+
+	/* wait to be given the lock */
+	for (;;) {
+		if (!waiter.task)
+			break;
+		schedule();
+		set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+	}
+
+	__set_task_state(tsk, TASK_RUNNING);
+ out:
+	;
+}
+
+/*
+ * trylock for reading -- returns 1 if successful, 0 if contention
+ */
+int __down_read_trylock(struct rw_semaphore *sem)
+{
+	unsigned long flags;
+	int ret = 0;
+
+
+	raw_spin_lock_irqsave(&sem->wait_lock, flags);
+
+	if (sem->count >= 0 && list_empty(&sem->wait_list)) {
+		/* granted */
+		sem->count++;
+		ret = 1;
+	}
+
+	raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
+
+	return ret;
+}
+
+/*
+ * get a write lock on the semaphore
+ */
+void __sched __down_write_nested(struct rw_semaphore *sem, int subclass)
+{
+	struct rwsem_waiter waiter;
+	struct task_struct *tsk;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&sem->wait_lock, flags);
+
+	/* set up my own style of waitqueue */
+	tsk = current;
+	waiter.task = tsk;
+	waiter.type = RWSEM_WAITING_FOR_WRITE;
+	list_add_tail(&waiter.list, &sem->wait_list);
+
+	/* wait for someone to release the lock */
+	for (;;) {
+		/*
+		 * That is the key to support write lock stealing: allows the
+		 * task already on CPU to get the lock soon rather than put
+		 * itself into sleep and waiting for system woke it or someone
+		 * else in the head of the wait list up.
+		 */
+		if (sem->count == 0)
+			break;
+		set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+		raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
+		schedule();
+		raw_spin_lock_irqsave(&sem->wait_lock, flags);
+	}
+	/* got the lock */
+	sem->count = -1;
+	list_del(&waiter.list);
+
+	raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
+}
+
+void __sched __down_write(struct rw_semaphore *sem)
+{
+	__down_write_nested(sem, 0);
+}
+
+/*
+ * trylock for writing -- returns 1 if successful, 0 if contention
+ */
+int __down_write_trylock(struct rw_semaphore *sem)
+{
+	unsigned long flags;
+	int ret = 0;
+
+	raw_spin_lock_irqsave(&sem->wait_lock, flags);
+
+	if (sem->count == 0) {
+		/* got the lock */
+		sem->count = -1;
+		ret = 1;
+	}
+
+	raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
+
+	return ret;
+}
+
+/*
+ * release a read lock on the semaphore
+ */
+void __up_read(struct rw_semaphore *sem)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&sem->wait_lock, flags);
+
+	if (--sem->count == 0 && !list_empty(&sem->wait_list))
+		sem = __rwsem_wake_one_writer(sem);
+
+	raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
+}
+
+/*
+ * release a write lock on the semaphore
+ */
+void __up_write(struct rw_semaphore *sem)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&sem->wait_lock, flags);
+
+	sem->count = 0;
+	if (!list_empty(&sem->wait_list))
+		sem = __rwsem_do_wake(sem, 1);
+
+	raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
+}
+
+/*
+ * downgrade a write lock into a read lock
+ * - just wake up any readers at the front of the queue
+ */
+void __downgrade_write(struct rw_semaphore *sem)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&sem->wait_lock, flags);
+
+	sem->count = 1;
+	if (!list_empty(&sem->wait_list))
+		sem = __rwsem_do_wake(sem, 0);
+
+	raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
+}
+
diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c
new file mode 100644
index 000000000..3417d0172
--- /dev/null
+++ b/kernel/locking/rwsem-xadd.c
@@ -0,0 +1,531 @@
+/* rwsem.c: R/W semaphores: contention handling functions
+ *
+ * Written by David Howells (dhowells@redhat.com).
+ * Derived from arch/i386/kernel/semaphore.c
+ *
+ * Writer lock-stealing by Alex Shi <alex.shi@intel.com>
+ * and Michel Lespinasse <walken@google.com>
+ *
+ * Optimistic spinning by Tim Chen <tim.c.chen@intel.com>
+ * and Davidlohr Bueso <davidlohr@hp.com>. Based on mutexes.
+ */
+#include <linux/rwsem.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <linux/export.h>
+#include <linux/sched/rt.h>
+#include <linux/osq_lock.h>
+
+#include "rwsem.h"
+
+/*
+ * Guide to the rw_semaphore's count field for common values.
+ * (32-bit case illustrated, similar for 64-bit)
+ *
+ * 0x0000000X	(1) X readers active or attempting lock, no writer waiting
+ *		    X = #active_readers + #readers attempting to lock
+ *		    (X*ACTIVE_BIAS)
+ *
+ * 0x00000000	rwsem is unlocked, and no one is waiting for the lock or
+ *		attempting to read lock or write lock.
+ *
+ * 0xffff000X	(1) X readers active or attempting lock, with waiters for lock
+ *		    X = #active readers + # readers attempting lock
+ *		    (X*ACTIVE_BIAS + WAITING_BIAS)
+ *		(2) 1 writer attempting lock, no waiters for lock
+ *		    X-1 = #active readers + #readers attempting lock
+ *		    ((X-1)*ACTIVE_BIAS + ACTIVE_WRITE_BIAS)
+ *		(3) 1 writer active, no waiters for lock
+ *		    X-1 = #active readers + #readers attempting lock
+ *		    ((X-1)*ACTIVE_BIAS + ACTIVE_WRITE_BIAS)
+ *
+ * 0xffff0001	(1) 1 reader active or attempting lock, waiters for lock
+ *		    (WAITING_BIAS + ACTIVE_BIAS)
+ *		(2) 1 writer active or attempting lock, no waiters for lock
+ *		    (ACTIVE_WRITE_BIAS)
+ *
+ * 0xffff0000	(1) There are writers or readers queued but none active
+ *		    or in the process of attempting lock.
+ *		    (WAITING_BIAS)
+ *		Note: writer can attempt to steal lock for this count by adding
+ *		ACTIVE_WRITE_BIAS in cmpxchg and checking the old count
+ *
+ * 0xfffe0001	(1) 1 writer active, or attempting lock. Waiters on queue.
+ *		    (ACTIVE_WRITE_BIAS + WAITING_BIAS)
+ *
+ * Note: Readers attempt to lock by adding ACTIVE_BIAS in down_read and checking
+ *	 the count becomes more than 0 for successful lock acquisition,
+ *	 i.e. the case where there are only readers or nobody has lock.
+ *	 (1st and 2nd case above).
+ *
+ *	 Writers attempt to lock by adding ACTIVE_WRITE_BIAS in down_write and
+ *	 checking the count becomes ACTIVE_WRITE_BIAS for successful lock
+ *	 acquisition (i.e. nobody else has lock or attempts lock).  If
+ *	 unsuccessful, in rwsem_down_write_failed, we'll check to see if there
+ *	 are only waiters but none active (5th case above), and attempt to
+ *	 steal the lock.
+ *
+ */
+
+/*
+ * Initialize an rwsem:
+ */
+void __init_rwsem(struct rw_semaphore *sem, const char *name,
+		  struct lock_class_key *key)
+{
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	/*
+	 * Make sure we are not reinitializing a held semaphore:
+	 */
+	debug_check_no_locks_freed((void *)sem, sizeof(*sem));
+	lockdep_init_map(&sem->dep_map, name, key, 0);
+#endif
+	sem->count = RWSEM_UNLOCKED_VALUE;
+	raw_spin_lock_init(&sem->wait_lock);
+	INIT_LIST_HEAD(&sem->wait_list);
+#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
+	sem->owner = NULL;
+	osq_lock_init(&sem->osq);
+#endif
+}
+
+EXPORT_SYMBOL(__init_rwsem);
+
+enum rwsem_waiter_type {
+	RWSEM_WAITING_FOR_WRITE,
+	RWSEM_WAITING_FOR_READ
+};
+
+struct rwsem_waiter {
+	struct list_head list;
+	struct task_struct *task;
+	enum rwsem_waiter_type type;
+};
+
+enum rwsem_wake_type {
+	RWSEM_WAKE_ANY,		/* Wake whatever's at head of wait list */
+	RWSEM_WAKE_READERS,	/* Wake readers only */
+	RWSEM_WAKE_READ_OWNED	/* Waker thread holds the read lock */
+};
+
+/*
+ * handle the lock release when processes blocked on it that can now run
+ * - if we come here from up_xxxx(), then:
+ *   - the 'active part' of count (&0x0000ffff) reached 0 (but may have changed)
+ *   - the 'waiting part' of count (&0xffff0000) is -ve (and will still be so)
+ * - there must be someone on the queue
+ * - the spinlock must be held by the caller
+ * - woken process blocks are discarded from the list after having task zeroed
+ * - writers are only woken if downgrading is false
+ */
+static struct rw_semaphore *
+__rwsem_do_wake(struct rw_semaphore *sem, enum rwsem_wake_type wake_type)
+{
+	struct rwsem_waiter *waiter;
+	struct task_struct *tsk;
+	struct list_head *next;
+	long oldcount, woken, loop, adjustment;
+
+	waiter = list_entry(sem->wait_list.next, struct rwsem_waiter, list);
+	if (waiter->type == RWSEM_WAITING_FOR_WRITE) {
+		if (wake_type == RWSEM_WAKE_ANY)
+			/* Wake writer at the front of the queue, but do not
+			 * grant it the lock yet as we want other writers
+			 * to be able to steal it.  Readers, on the other hand,
+			 * will block as they will notice the queued writer.
+			 */
+			wake_up_process(waiter->task);
+		goto out;
+	}
+
+	/* Writers might steal the lock before we grant it to the next reader.
+	 * We prefer to do the first reader grant before counting readers
+	 * so we can bail out early if a writer stole the lock.
+	 */
+	adjustment = 0;
+	if (wake_type != RWSEM_WAKE_READ_OWNED) {
+		adjustment = RWSEM_ACTIVE_READ_BIAS;
+ try_reader_grant:
+		oldcount = rwsem_atomic_update(adjustment, sem) - adjustment;
+		if (unlikely(oldcount < RWSEM_WAITING_BIAS)) {
+			/* A writer stole the lock. Undo our reader grant. */
+			if (rwsem_atomic_update(-adjustment, sem) &
+						RWSEM_ACTIVE_MASK)
+				goto out;
+			/* Last active locker left. Retry waking readers. */
+			goto try_reader_grant;
+		}
+	}
+
+	/* Grant an infinite number of read locks to the readers at the front
+	 * of the queue.  Note we increment the 'active part' of the count by
+	 * the number of readers before waking any processes up.
+	 */
+	woken = 0;
+	do {
+		woken++;
+
+		if (waiter->list.next == &sem->wait_list)
+			break;
+
+		waiter = list_entry(waiter->list.next,
+					struct rwsem_waiter, list);
+
+	} while (waiter->type != RWSEM_WAITING_FOR_WRITE);
+
+	adjustment = woken * RWSEM_ACTIVE_READ_BIAS - adjustment;
+	if (waiter->type != RWSEM_WAITING_FOR_WRITE)
+		/* hit end of list above */
+		adjustment -= RWSEM_WAITING_BIAS;
+
+	if (adjustment)
+		rwsem_atomic_add(adjustment, sem);
+
+	next = sem->wait_list.next;
+	loop = woken;
+	do {
+		waiter = list_entry(next, struct rwsem_waiter, list);
+		next = waiter->list.next;
+		tsk = waiter->task;
+		/*
+		 * Make sure we do not wakeup the next reader before
+		 * setting the nil condition to grant the next reader;
+		 * otherwise we could miss the wakeup on the other
+		 * side and end up sleeping again. See the pairing
+		 * in rwsem_down_read_failed().
+		 */
+		smp_mb();
+		waiter->task = NULL;
+		wake_up_process(tsk);
+		put_task_struct(tsk);
+	} while (--loop);
+
+	sem->wait_list.next = next;
+	next->prev = &sem->wait_list;
+
+ out:
+	return sem;
+}
+
+/*
+ * Wait for the read lock to be granted
+ */
+__visible
+struct rw_semaphore __sched *rwsem_down_read_failed(struct rw_semaphore *sem)
+{
+	long count, adjustment = -RWSEM_ACTIVE_READ_BIAS;
+	struct rwsem_waiter waiter;
+	struct task_struct *tsk = current;
+
+	/* set up my own style of waitqueue */
+	waiter.task = tsk;
+	waiter.type = RWSEM_WAITING_FOR_READ;
+	get_task_struct(tsk);
+
+	raw_spin_lock_irq(&sem->wait_lock);
+	if (list_empty(&sem->wait_list))
+		adjustment += RWSEM_WAITING_BIAS;
+	list_add_tail(&waiter.list, &sem->wait_list);
+
+	/* we're now waiting on the lock, but no longer actively locking */
+	count = rwsem_atomic_update(adjustment, sem);
+
+	/* If there are no active locks, wake the front queued process(es).
+	 *
+	 * If there are no writers and we are first in the queue,
+	 * wake our own waiter to join the existing active readers !
+	 */
+	if (count == RWSEM_WAITING_BIAS ||
+	    (count > RWSEM_WAITING_BIAS &&
+	     adjustment != -RWSEM_ACTIVE_READ_BIAS))
+		sem = __rwsem_do_wake(sem, RWSEM_WAKE_ANY);
+
+	raw_spin_unlock_irq(&sem->wait_lock);
+
+	/* wait to be given the lock */
+	while (true) {
+		set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+		if (!waiter.task)
+			break;
+		schedule();
+	}
+
+	__set_task_state(tsk, TASK_RUNNING);
+	return sem;
+}
+EXPORT_SYMBOL(rwsem_down_read_failed);
+
+static inline bool rwsem_try_write_lock(long count, struct rw_semaphore *sem)
+{
+	/*
+	 * Try acquiring the write lock. Check count first in order
+	 * to reduce unnecessary expensive cmpxchg() operations.
+	 */
+	if (count == RWSEM_WAITING_BIAS &&
+	    cmpxchg(&sem->count, RWSEM_WAITING_BIAS,
+		    RWSEM_ACTIVE_WRITE_BIAS) == RWSEM_WAITING_BIAS) {
+		if (!list_is_singular(&sem->wait_list))
+			rwsem_atomic_update(RWSEM_WAITING_BIAS, sem);
+		rwsem_set_owner(sem);
+		return true;
+	}
+
+	return false;
+}
+
+#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
+/*
+ * Try to acquire write lock before the writer has been put on wait queue.
+ */
+static inline bool rwsem_try_write_lock_unqueued(struct rw_semaphore *sem)
+{
+	long old, count = READ_ONCE(sem->count);
+
+	while (true) {
+		if (!(count == 0 || count == RWSEM_WAITING_BIAS))
+			return false;
+
+		old = cmpxchg(&sem->count, count, count + RWSEM_ACTIVE_WRITE_BIAS);
+		if (old == count) {
+			rwsem_set_owner(sem);
+			return true;
+		}
+
+		count = old;
+	}
+}
+
+static inline bool rwsem_can_spin_on_owner(struct rw_semaphore *sem)
+{
+	struct task_struct *owner;
+	bool ret = true;
+
+	if (need_resched())
+		return false;
+
+	rcu_read_lock();
+	owner = READ_ONCE(sem->owner);
+	if (!owner) {
+		long count = READ_ONCE(sem->count);
+		/*
+		 * If sem->owner is not set, yet we have just recently entered the
+		 * slowpath with the lock being active, then there is a possibility
+		 * reader(s) may have the lock. To be safe, bail spinning in these
+		 * situations.
+		 */
+		if (count & RWSEM_ACTIVE_MASK)
+			ret = false;
+		goto done;
+	}
+
+	ret = owner->on_cpu;
+done:
+	rcu_read_unlock();
+	return ret;
+}
+
+static noinline
+bool rwsem_spin_on_owner(struct rw_semaphore *sem, struct task_struct *owner)
+{
+	long count;
+
+	rcu_read_lock();
+	while (sem->owner == owner) {
+		/*
+		 * Ensure we emit the owner->on_cpu, dereference _after_
+		 * checking sem->owner still matches owner, if that fails,
+		 * owner might point to free()d memory, if it still matches,
+		 * the rcu_read_lock() ensures the memory stays valid.
+		 */
+		barrier();
+
+		/* abort spinning when need_resched or owner is not running */
+		if (!owner->on_cpu || need_resched()) {
+			rcu_read_unlock();
+			return false;
+		}
+
+		cpu_relax_lowlatency();
+	}
+	rcu_read_unlock();
+
+	if (READ_ONCE(sem->owner))
+		return true; /* new owner, continue spinning */
+
+	/*
+	 * When the owner is not set, the lock could be free or
+	 * held by readers. Check the counter to verify the
+	 * state.
+	 */
+	count = READ_ONCE(sem->count);
+	return (count == 0 || count == RWSEM_WAITING_BIAS);
+}
+
+static bool rwsem_optimistic_spin(struct rw_semaphore *sem)
+{
+	struct task_struct *owner;
+	bool taken = false;
+
+	preempt_disable();
+
+	/* sem->wait_lock should not be held when doing optimistic spinning */
+	if (!rwsem_can_spin_on_owner(sem))
+		goto done;
+
+	if (!osq_lock(&sem->osq))
+		goto done;
+
+	while (true) {
+		owner = READ_ONCE(sem->owner);
+		if (owner && !rwsem_spin_on_owner(sem, owner))
+			break;
+
+		/* wait_lock will be acquired if write_lock is obtained */
+		if (rwsem_try_write_lock_unqueued(sem)) {
+			taken = true;
+			break;
+		}
+
+		/*
+		 * When there's no owner, we might have preempted between the
+		 * owner acquiring the lock and setting the owner field. If
+		 * we're an RT task that will live-lock because we won't let
+		 * the owner complete.
+		 */
+		if (!owner && (need_resched() || rt_task(current)))
+			break;
+
+		/*
+		 * The cpu_relax() call is a compiler barrier which forces
+		 * everything in this loop to be re-loaded. We don't need
+		 * memory barriers as we'll eventually observe the right
+		 * values at the cost of a few extra spins.
+		 */
+		cpu_relax_lowlatency();
+	}
+	osq_unlock(&sem->osq);
+done:
+	preempt_enable();
+	return taken;
+}
+
+#else
+static bool rwsem_optimistic_spin(struct rw_semaphore *sem)
+{
+	return false;
+}
+#endif
+
+/*
+ * Wait until we successfully acquire the write lock
+ */
+__visible
+struct rw_semaphore __sched *rwsem_down_write_failed(struct rw_semaphore *sem)
+{
+	long count;
+	bool waiting = true; /* any queued threads before us */
+	struct rwsem_waiter waiter;
+
+	/* undo write bias from down_write operation, stop active locking */
+	count = rwsem_atomic_update(-RWSEM_ACTIVE_WRITE_BIAS, sem);
+
+	/* do optimistic spinning and steal lock if possible */
+	if (rwsem_optimistic_spin(sem))
+		return sem;
+
+	/*
+	 * Optimistic spinning failed, proceed to the slowpath
+	 * and block until we can acquire the sem.
+	 */
+	waiter.task = current;
+	waiter.type = RWSEM_WAITING_FOR_WRITE;
+
+	raw_spin_lock_irq(&sem->wait_lock);
+
+	/* account for this before adding a new element to the list */
+	if (list_empty(&sem->wait_list))
+		waiting = false;
+
+	list_add_tail(&waiter.list, &sem->wait_list);
+
+	/* we're now waiting on the lock, but no longer actively locking */
+	if (waiting) {
+		count = READ_ONCE(sem->count);
+
+		/*
+		 * If there were already threads queued before us and there are
+		 * no active writers, the lock must be read owned; so we try to
+		 * wake any read locks that were queued ahead of us.
+		 */
+		if (count > RWSEM_WAITING_BIAS)
+			sem = __rwsem_do_wake(sem, RWSEM_WAKE_READERS);
+
+	} else
+		count = rwsem_atomic_update(RWSEM_WAITING_BIAS, sem);
+
+	/* wait until we successfully acquire the lock */
+	set_current_state(TASK_UNINTERRUPTIBLE);
+	while (true) {
+		if (rwsem_try_write_lock(count, sem))
+			break;
+		raw_spin_unlock_irq(&sem->wait_lock);
+
+		/* Block until there are no active lockers. */
+		do {
+			schedule();
+			set_current_state(TASK_UNINTERRUPTIBLE);
+		} while ((count = sem->count) & RWSEM_ACTIVE_MASK);
+
+		raw_spin_lock_irq(&sem->wait_lock);
+	}
+	__set_current_state(TASK_RUNNING);
+
+	list_del(&waiter.list);
+	raw_spin_unlock_irq(&sem->wait_lock);
+
+	return sem;
+}
+EXPORT_SYMBOL(rwsem_down_write_failed);
+
+/*
+ * handle waking up a waiter on the semaphore
+ * - up_read/up_write has decremented the active part of count if we come here
+ */
+__visible
+struct rw_semaphore *rwsem_wake(struct rw_semaphore *sem)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&sem->wait_lock, flags);
+
+	/* do nothing if list empty */
+	if (!list_empty(&sem->wait_list))
+		sem = __rwsem_do_wake(sem, RWSEM_WAKE_ANY);
+
+	raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
+
+	return sem;
+}
+EXPORT_SYMBOL(rwsem_wake);
+
+/*
+ * downgrade a write lock into a read lock
+ * - caller incremented waiting part of count and discovered it still negative
+ * - just wake up any readers at the front of the queue
+ */
+__visible
+struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&sem->wait_lock, flags);
+
+	/* do nothing if list empty */
+	if (!list_empty(&sem->wait_list))
+		sem = __rwsem_do_wake(sem, RWSEM_WAKE_READ_OWNED);
+
+	raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
+
+	return sem;
+}
+EXPORT_SYMBOL(rwsem_downgrade_wake);
diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
new file mode 100644
index 000000000..205be0ce3
--- /dev/null
+++ b/kernel/locking/rwsem.c
@@ -0,0 +1,166 @@
+/* kernel/rwsem.c: R/W semaphores, public implementation
+ *
+ * Written by David Howells (dhowells@redhat.com).
+ * Derived from asm-i386/semaphore.h
+ */
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/export.h>
+#include <linux/rwsem.h>
+#include <linux/atomic.h>
+
+#include "rwsem.h"
+
+/*
+ * lock for reading
+ */
+void __sched down_read(struct rw_semaphore *sem)
+{
+	might_sleep();
+	rwsem_acquire_read(&sem->dep_map, 0, 0, _RET_IP_);
+
+	LOCK_CONTENDED(sem, __down_read_trylock, __down_read);
+}
+
+EXPORT_SYMBOL(down_read);
+
+/*
+ * trylock for reading -- returns 1 if successful, 0 if contention
+ */
+int down_read_trylock(struct rw_semaphore *sem)
+{
+	int ret = __down_read_trylock(sem);
+
+	if (ret == 1)
+		rwsem_acquire_read(&sem->dep_map, 0, 1, _RET_IP_);
+	return ret;
+}
+
+EXPORT_SYMBOL(down_read_trylock);
+
+/*
+ * lock for writing
+ */
+void __sched down_write(struct rw_semaphore *sem)
+{
+	might_sleep();
+	rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_);
+
+	LOCK_CONTENDED(sem, __down_write_trylock, __down_write);
+	rwsem_set_owner(sem);
+}
+
+EXPORT_SYMBOL(down_write);
+
+/*
+ * trylock for writing -- returns 1 if successful, 0 if contention
+ */
+int down_write_trylock(struct rw_semaphore *sem)
+{
+	int ret = __down_write_trylock(sem);
+
+	if (ret == 1) {
+		rwsem_acquire(&sem->dep_map, 0, 1, _RET_IP_);
+		rwsem_set_owner(sem);
+	}
+
+	return ret;
+}
+
+EXPORT_SYMBOL(down_write_trylock);
+
+/*
+ * release a read lock
+ */
+void up_read(struct rw_semaphore *sem)
+{
+	rwsem_release(&sem->dep_map, 1, _RET_IP_);
+
+	__up_read(sem);
+}
+
+EXPORT_SYMBOL(up_read);
+
+/*
+ * release a write lock
+ */
+void up_write(struct rw_semaphore *sem)
+{
+	rwsem_release(&sem->dep_map, 1, _RET_IP_);
+
+	rwsem_clear_owner(sem);
+	__up_write(sem);
+}
+
+EXPORT_SYMBOL(up_write);
+
+/*
+ * downgrade write lock to read lock
+ */
+void downgrade_write(struct rw_semaphore *sem)
+{
+	/*
+	 * lockdep: a downgraded write will live on as a write
+	 * dependency.
+	 */
+	rwsem_clear_owner(sem);
+	__downgrade_write(sem);
+}
+
+EXPORT_SYMBOL(downgrade_write);
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+
+void down_read_nested(struct rw_semaphore *sem, int subclass)
+{
+	might_sleep();
+	rwsem_acquire_read(&sem->dep_map, subclass, 0, _RET_IP_);
+
+	LOCK_CONTENDED(sem, __down_read_trylock, __down_read);
+}
+
+EXPORT_SYMBOL(down_read_nested);
+
+void _down_write_nest_lock(struct rw_semaphore *sem, struct lockdep_map *nest)
+{
+	might_sleep();
+	rwsem_acquire_nest(&sem->dep_map, 0, 0, nest, _RET_IP_);
+
+	LOCK_CONTENDED(sem, __down_write_trylock, __down_write);
+	rwsem_set_owner(sem);
+}
+
+EXPORT_SYMBOL(_down_write_nest_lock);
+
+void down_read_non_owner(struct rw_semaphore *sem)
+{
+	might_sleep();
+
+	__down_read(sem);
+}
+
+EXPORT_SYMBOL(down_read_non_owner);
+
+void down_write_nested(struct rw_semaphore *sem, int subclass)
+{
+	might_sleep();
+	rwsem_acquire(&sem->dep_map, subclass, 0, _RET_IP_);
+
+	LOCK_CONTENDED(sem, __down_write_trylock, __down_write);
+	rwsem_set_owner(sem);
+}
+
+EXPORT_SYMBOL(down_write_nested);
+
+void up_read_non_owner(struct rw_semaphore *sem)
+{
+	__up_read(sem);
+}
+
+EXPORT_SYMBOL(up_read_non_owner);
+
+#endif
+
+
diff --git a/kernel/locking/rwsem.h b/kernel/locking/rwsem.h
new file mode 100644
index 000000000..870ed9a5b
--- /dev/null
+++ b/kernel/locking/rwsem.h
@@ -0,0 +1,20 @@
+#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
+static inline void rwsem_set_owner(struct rw_semaphore *sem)
+{
+	sem->owner = current;
+}
+
+static inline void rwsem_clear_owner(struct rw_semaphore *sem)
+{
+	sem->owner = NULL;
+}
+
+#else
+static inline void rwsem_set_owner(struct rw_semaphore *sem)
+{
+}
+
+static inline void rwsem_clear_owner(struct rw_semaphore *sem)
+{
+}
+#endif
diff --git a/kernel/locking/semaphore.c b/kernel/locking/semaphore.c
new file mode 100644
index 000000000..b8120abe5
--- /dev/null
+++ b/kernel/locking/semaphore.c
@@ -0,0 +1,263 @@
+/*
+ * Copyright (c) 2008 Intel Corporation
+ * Author: Matthew Wilcox <willy@linux.intel.com>
+ *
+ * Distributed under the terms of the GNU GPL, version 2
+ *
+ * This file implements counting semaphores.
+ * A counting semaphore may be acquired 'n' times before sleeping.
+ * See mutex.c for single-acquisition sleeping locks which enforce
+ * rules which allow code to be debugged more easily.
+ */
+
+/*
+ * Some notes on the implementation:
+ *
+ * The spinlock controls access to the other members of the semaphore.
+ * down_trylock() and up() can be called from interrupt context, so we
+ * have to disable interrupts when taking the lock.  It turns out various
+ * parts of the kernel expect to be able to use down() on a semaphore in
+ * interrupt context when they know it will succeed, so we have to use
+ * irqsave variants for down(), down_interruptible() and down_killable()
+ * too.
+ *
+ * The ->count variable represents how many more tasks can acquire this
+ * semaphore.  If it's zero, there may be tasks waiting on the wait_list.
+ */
+
+#include <linux/compiler.h>
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/sched.h>
+#include <linux/semaphore.h>
+#include <linux/spinlock.h>
+#include <linux/ftrace.h>
+
+static noinline void __down(struct semaphore *sem);
+static noinline int __down_interruptible(struct semaphore *sem);
+static noinline int __down_killable(struct semaphore *sem);
+static noinline int __down_timeout(struct semaphore *sem, long timeout);
+static noinline void __up(struct semaphore *sem);
+
+/**
+ * down - acquire the semaphore
+ * @sem: the semaphore to be acquired
+ *
+ * Acquires the semaphore.  If no more tasks are allowed to acquire the
+ * semaphore, calling this function will put the task to sleep until the
+ * semaphore is released.
+ *
+ * Use of this function is deprecated, please use down_interruptible() or
+ * down_killable() instead.
+ */
+void down(struct semaphore *sem)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&sem->lock, flags);
+	if (likely(sem->count > 0))
+		sem->count--;
+	else
+		__down(sem);
+	raw_spin_unlock_irqrestore(&sem->lock, flags);
+}
+EXPORT_SYMBOL(down);
+
+/**
+ * down_interruptible - acquire the semaphore unless interrupted
+ * @sem: the semaphore to be acquired
+ *
+ * Attempts to acquire the semaphore.  If no more tasks are allowed to
+ * acquire the semaphore, calling this function will put the task to sleep.
+ * If the sleep is interrupted by a signal, this function will return -EINTR.
+ * If the semaphore is successfully acquired, this function returns 0.
+ */
+int down_interruptible(struct semaphore *sem)
+{
+	unsigned long flags;
+	int result = 0;
+
+	raw_spin_lock_irqsave(&sem->lock, flags);
+	if (likely(sem->count > 0))
+		sem->count--;
+	else
+		result = __down_interruptible(sem);
+	raw_spin_unlock_irqrestore(&sem->lock, flags);
+
+	return result;
+}
+EXPORT_SYMBOL(down_interruptible);
+
+/**
+ * down_killable - acquire the semaphore unless killed
+ * @sem: the semaphore to be acquired
+ *
+ * Attempts to acquire the semaphore.  If no more tasks are allowed to
+ * acquire the semaphore, calling this function will put the task to sleep.
+ * If the sleep is interrupted by a fatal signal, this function will return
+ * -EINTR.  If the semaphore is successfully acquired, this function returns
+ * 0.
+ */
+int down_killable(struct semaphore *sem)
+{
+	unsigned long flags;
+	int result = 0;
+
+	raw_spin_lock_irqsave(&sem->lock, flags);
+	if (likely(sem->count > 0))
+		sem->count--;
+	else
+		result = __down_killable(sem);
+	raw_spin_unlock_irqrestore(&sem->lock, flags);
+
+	return result;
+}
+EXPORT_SYMBOL(down_killable);
+
+/**
+ * down_trylock - try to acquire the semaphore, without waiting
+ * @sem: the semaphore to be acquired
+ *
+ * Try to acquire the semaphore atomically.  Returns 0 if the semaphore has
+ * been acquired successfully or 1 if it it cannot be acquired.
+ *
+ * NOTE: This return value is inverted from both spin_trylock and
+ * mutex_trylock!  Be careful about this when converting code.
+ *
+ * Unlike mutex_trylock, this function can be used from interrupt context,
+ * and the semaphore can be released by any task or interrupt.
+ */
+int down_trylock(struct semaphore *sem)
+{
+	unsigned long flags;
+	int count;
+
+	raw_spin_lock_irqsave(&sem->lock, flags);
+	count = sem->count - 1;
+	if (likely(count >= 0))
+		sem->count = count;
+	raw_spin_unlock_irqrestore(&sem->lock, flags);
+
+	return (count < 0);
+}
+EXPORT_SYMBOL(down_trylock);
+
+/**
+ * down_timeout - acquire the semaphore within a specified time
+ * @sem: the semaphore to be acquired
+ * @timeout: how long to wait before failing
+ *
+ * Attempts to acquire the semaphore.  If no more tasks are allowed to
+ * acquire the semaphore, calling this function will put the task to sleep.
+ * If the semaphore is not released within the specified number of jiffies,
+ * this function returns -ETIME.  It returns 0 if the semaphore was acquired.
+ */
+int down_timeout(struct semaphore *sem, long timeout)
+{
+	unsigned long flags;
+	int result = 0;
+
+	raw_spin_lock_irqsave(&sem->lock, flags);
+	if (likely(sem->count > 0))
+		sem->count--;
+	else
+		result = __down_timeout(sem, timeout);
+	raw_spin_unlock_irqrestore(&sem->lock, flags);
+
+	return result;
+}
+EXPORT_SYMBOL(down_timeout);
+
+/**
+ * up - release the semaphore
+ * @sem: the semaphore to release
+ *
+ * Release the semaphore.  Unlike mutexes, up() may be called from any
+ * context and even by tasks which have never called down().
+ */
+void up(struct semaphore *sem)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&sem->lock, flags);
+	if (likely(list_empty(&sem->wait_list)))
+		sem->count++;
+	else
+		__up(sem);
+	raw_spin_unlock_irqrestore(&sem->lock, flags);
+}
+EXPORT_SYMBOL(up);
+
+/* Functions for the contended case */
+
+struct semaphore_waiter {
+	struct list_head list;
+	struct task_struct *task;
+	bool up;
+};
+
+/*
+ * Because this function is inlined, the 'state' parameter will be
+ * constant, and thus optimised away by the compiler.  Likewise the
+ * 'timeout' parameter for the cases without timeouts.
+ */
+static inline int __sched __down_common(struct semaphore *sem, long state,
+								long timeout)
+{
+	struct task_struct *task = current;
+	struct semaphore_waiter waiter;
+
+	list_add_tail(&waiter.list, &sem->wait_list);
+	waiter.task = task;
+	waiter.up = false;
+
+	for (;;) {
+		if (signal_pending_state(state, task))
+			goto interrupted;
+		if (unlikely(timeout <= 0))
+			goto timed_out;
+		__set_task_state(task, state);
+		raw_spin_unlock_irq(&sem->lock);
+		timeout = schedule_timeout(timeout);
+		raw_spin_lock_irq(&sem->lock);
+		if (waiter.up)
+			return 0;
+	}
+
+ timed_out:
+	list_del(&waiter.list);
+	return -ETIME;
+
+ interrupted:
+	list_del(&waiter.list);
+	return -EINTR;
+}
+
+static noinline void __sched __down(struct semaphore *sem)
+{
+	__down_common(sem, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
+}
+
+static noinline int __sched __down_interruptible(struct semaphore *sem)
+{
+	return __down_common(sem, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
+}
+
+static noinline int __sched __down_killable(struct semaphore *sem)
+{
+	return __down_common(sem, TASK_KILLABLE, MAX_SCHEDULE_TIMEOUT);
+}
+
+static noinline int __sched __down_timeout(struct semaphore *sem, long timeout)
+{
+	return __down_common(sem, TASK_UNINTERRUPTIBLE, timeout);
+}
+
+static noinline void __sched __up(struct semaphore *sem)
+{
+	struct semaphore_waiter *waiter = list_first_entry(&sem->wait_list,
+						struct semaphore_waiter, list);
+	list_del(&waiter->list);
+	waiter->up = true;
+	wake_up_process(waiter->task);
+}
diff --git a/kernel/locking/spinlock.c b/kernel/locking/spinlock.c
new file mode 100644
index 000000000..db3ccb1dd
--- /dev/null
+++ b/kernel/locking/spinlock.c
@@ -0,0 +1,407 @@
+/*
+ * Copyright (2004) Linus Torvalds
+ *
+ * Author: Zwane Mwaikambo <zwane@fsmlabs.com>
+ *
+ * Copyright (2004, 2005) Ingo Molnar
+ *
+ * This file contains the spinlock/rwlock implementations for the
+ * SMP and the DEBUG_SPINLOCK cases. (UP-nondebug inlines them)
+ *
+ * Note that some architectures have special knowledge about the
+ * stack frames of these functions in their profile_pc. If you
+ * change anything significant here that could change the stack
+ * frame contact the architecture maintainers.
+ */
+
+#include <linux/linkage.h>
+#include <linux/preempt.h>
+#include <linux/spinlock.h>
+#include <linux/interrupt.h>
+#include <linux/debug_locks.h>
+#include <linux/export.h>
+
+/*
+ * If lockdep is enabled then we use the non-preemption spin-ops
+ * even on CONFIG_PREEMPT, because lockdep assumes that interrupts are
+ * not re-enabled during lock-acquire (which the preempt-spin-ops do):
+ */
+#if !defined(CONFIG_GENERIC_LOCKBREAK) || defined(CONFIG_DEBUG_LOCK_ALLOC)
+/*
+ * The __lock_function inlines are taken from
+ * include/linux/spinlock_api_smp.h
+ */
+#else
+#define raw_read_can_lock(l)	read_can_lock(l)
+#define raw_write_can_lock(l)	write_can_lock(l)
+
+/*
+ * Some architectures can relax in favour of the CPU owning the lock.
+ */
+#ifndef arch_read_relax
+# define arch_read_relax(l)	cpu_relax()
+#endif
+#ifndef arch_write_relax
+# define arch_write_relax(l)	cpu_relax()
+#endif
+#ifndef arch_spin_relax
+# define arch_spin_relax(l)	cpu_relax()
+#endif
+
+/*
+ * We build the __lock_function inlines here. They are too large for
+ * inlining all over the place, but here is only one user per function
+ * which embedds them into the calling _lock_function below.
+ *
+ * This could be a long-held lock. We both prepare to spin for a long
+ * time (making _this_ CPU preemptable if possible), and we also signal
+ * towards that other CPU that it should break the lock ASAP.
+ */
+#define BUILD_LOCK_OPS(op, locktype)					\
+void __lockfunc __raw_##op##_lock(locktype##_t *lock)			\
+{									\
+	for (;;) {							\
+		preempt_disable();					\
+		if (likely(do_raw_##op##_trylock(lock)))		\
+			break;						\
+		preempt_enable();					\
+									\
+		if (!(lock)->break_lock)				\
+			(lock)->break_lock = 1;				\
+		while (!raw_##op##_can_lock(lock) && (lock)->break_lock)\
+			arch_##op##_relax(&lock->raw_lock);		\
+	}								\
+	(lock)->break_lock = 0;						\
+}									\
+									\
+unsigned long __lockfunc __raw_##op##_lock_irqsave(locktype##_t *lock)	\
+{									\
+	unsigned long flags;						\
+									\
+	for (;;) {							\
+		preempt_disable();					\
+		local_irq_save(flags);					\
+		if (likely(do_raw_##op##_trylock(lock)))		\
+			break;						\
+		local_irq_restore(flags);				\
+		preempt_enable();					\
+									\
+		if (!(lock)->break_lock)				\
+			(lock)->break_lock = 1;				\
+		while (!raw_##op##_can_lock(lock) && (lock)->break_lock)\
+			arch_##op##_relax(&lock->raw_lock);		\
+	}								\
+	(lock)->break_lock = 0;						\
+	return flags;							\
+}									\
+									\
+void __lockfunc __raw_##op##_lock_irq(locktype##_t *lock)		\
+{									\
+	_raw_##op##_lock_irqsave(lock);					\
+}									\
+									\
+void __lockfunc __raw_##op##_lock_bh(locktype##_t *lock)		\
+{									\
+	unsigned long flags;						\
+									\
+	/*							*/	\
+	/* Careful: we must exclude softirqs too, hence the	*/	\
+	/* irq-disabling. We use the generic preemption-aware	*/	\
+	/* function:						*/	\
+	/**/								\
+	flags = _raw_##op##_lock_irqsave(lock);				\
+	local_bh_disable();						\
+	local_irq_restore(flags);					\
+}									\
+
+/*
+ * Build preemption-friendly versions of the following
+ * lock-spinning functions:
+ *
+ *         __[spin|read|write]_lock()
+ *         __[spin|read|write]_lock_irq()
+ *         __[spin|read|write]_lock_irqsave()
+ *         __[spin|read|write]_lock_bh()
+ */
+BUILD_LOCK_OPS(spin, raw_spinlock);
+BUILD_LOCK_OPS(read, rwlock);
+BUILD_LOCK_OPS(write, rwlock);
+
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_TRYLOCK
+int __lockfunc _raw_spin_trylock(raw_spinlock_t *lock)
+{
+	return __raw_spin_trylock(lock);
+}
+EXPORT_SYMBOL(_raw_spin_trylock);
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_TRYLOCK_BH
+int __lockfunc _raw_spin_trylock_bh(raw_spinlock_t *lock)
+{
+	return __raw_spin_trylock_bh(lock);
+}
+EXPORT_SYMBOL(_raw_spin_trylock_bh);
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_LOCK
+void __lockfunc _raw_spin_lock(raw_spinlock_t *lock)
+{
+	__raw_spin_lock(lock);
+}
+EXPORT_SYMBOL(_raw_spin_lock);
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_LOCK_IRQSAVE
+unsigned long __lockfunc _raw_spin_lock_irqsave(raw_spinlock_t *lock)
+{
+	return __raw_spin_lock_irqsave(lock);
+}
+EXPORT_SYMBOL(_raw_spin_lock_irqsave);
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_LOCK_IRQ
+void __lockfunc _raw_spin_lock_irq(raw_spinlock_t *lock)
+{
+	__raw_spin_lock_irq(lock);
+}
+EXPORT_SYMBOL(_raw_spin_lock_irq);
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_LOCK_BH
+void __lockfunc _raw_spin_lock_bh(raw_spinlock_t *lock)
+{
+	__raw_spin_lock_bh(lock);
+}
+EXPORT_SYMBOL(_raw_spin_lock_bh);
+#endif
+
+#ifdef CONFIG_UNINLINE_SPIN_UNLOCK
+void __lockfunc _raw_spin_unlock(raw_spinlock_t *lock)
+{
+	__raw_spin_unlock(lock);
+}
+EXPORT_SYMBOL(_raw_spin_unlock);
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_UNLOCK_IRQRESTORE
+void __lockfunc _raw_spin_unlock_irqrestore(raw_spinlock_t *lock, unsigned long flags)
+{
+	__raw_spin_unlock_irqrestore(lock, flags);
+}
+EXPORT_SYMBOL(_raw_spin_unlock_irqrestore);
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_UNLOCK_IRQ
+void __lockfunc _raw_spin_unlock_irq(raw_spinlock_t *lock)
+{
+	__raw_spin_unlock_irq(lock);
+}
+EXPORT_SYMBOL(_raw_spin_unlock_irq);
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_UNLOCK_BH
+void __lockfunc _raw_spin_unlock_bh(raw_spinlock_t *lock)
+{
+	__raw_spin_unlock_bh(lock);
+}
+EXPORT_SYMBOL(_raw_spin_unlock_bh);
+#endif
+
+#ifndef CONFIG_INLINE_READ_TRYLOCK
+int __lockfunc _raw_read_trylock(rwlock_t *lock)
+{
+	return __raw_read_trylock(lock);
+}
+EXPORT_SYMBOL(_raw_read_trylock);
+#endif
+
+#ifndef CONFIG_INLINE_READ_LOCK
+void __lockfunc _raw_read_lock(rwlock_t *lock)
+{
+	__raw_read_lock(lock);
+}
+EXPORT_SYMBOL(_raw_read_lock);
+#endif
+
+#ifndef CONFIG_INLINE_READ_LOCK_IRQSAVE
+unsigned long __lockfunc _raw_read_lock_irqsave(rwlock_t *lock)
+{
+	return __raw_read_lock_irqsave(lock);
+}
+EXPORT_SYMBOL(_raw_read_lock_irqsave);
+#endif
+
+#ifndef CONFIG_INLINE_READ_LOCK_IRQ
+void __lockfunc _raw_read_lock_irq(rwlock_t *lock)
+{
+	__raw_read_lock_irq(lock);
+}
+EXPORT_SYMBOL(_raw_read_lock_irq);
+#endif
+
+#ifndef CONFIG_INLINE_READ_LOCK_BH
+void __lockfunc _raw_read_lock_bh(rwlock_t *lock)
+{
+	__raw_read_lock_bh(lock);
+}
+EXPORT_SYMBOL(_raw_read_lock_bh);
+#endif
+
+#ifndef CONFIG_INLINE_READ_UNLOCK
+void __lockfunc _raw_read_unlock(rwlock_t *lock)
+{
+	__raw_read_unlock(lock);
+}
+EXPORT_SYMBOL(_raw_read_unlock);
+#endif
+
+#ifndef CONFIG_INLINE_READ_UNLOCK_IRQRESTORE
+void __lockfunc _raw_read_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
+{
+	__raw_read_unlock_irqrestore(lock, flags);
+}
+EXPORT_SYMBOL(_raw_read_unlock_irqrestore);
+#endif
+
+#ifndef CONFIG_INLINE_READ_UNLOCK_IRQ
+void __lockfunc _raw_read_unlock_irq(rwlock_t *lock)
+{
+	__raw_read_unlock_irq(lock);
+}
+EXPORT_SYMBOL(_raw_read_unlock_irq);
+#endif
+
+#ifndef CONFIG_INLINE_READ_UNLOCK_BH
+void __lockfunc _raw_read_unlock_bh(rwlock_t *lock)
+{
+	__raw_read_unlock_bh(lock);
+}
+EXPORT_SYMBOL(_raw_read_unlock_bh);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_TRYLOCK
+int __lockfunc _raw_write_trylock(rwlock_t *lock)
+{
+	return __raw_write_trylock(lock);
+}
+EXPORT_SYMBOL(_raw_write_trylock);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_LOCK
+void __lockfunc _raw_write_lock(rwlock_t *lock)
+{
+	__raw_write_lock(lock);
+}
+EXPORT_SYMBOL(_raw_write_lock);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_LOCK_IRQSAVE
+unsigned long __lockfunc _raw_write_lock_irqsave(rwlock_t *lock)
+{
+	return __raw_write_lock_irqsave(lock);
+}
+EXPORT_SYMBOL(_raw_write_lock_irqsave);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_LOCK_IRQ
+void __lockfunc _raw_write_lock_irq(rwlock_t *lock)
+{
+	__raw_write_lock_irq(lock);
+}
+EXPORT_SYMBOL(_raw_write_lock_irq);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_LOCK_BH
+void __lockfunc _raw_write_lock_bh(rwlock_t *lock)
+{
+	__raw_write_lock_bh(lock);
+}
+EXPORT_SYMBOL(_raw_write_lock_bh);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_UNLOCK
+void __lockfunc _raw_write_unlock(rwlock_t *lock)
+{
+	__raw_write_unlock(lock);
+}
+EXPORT_SYMBOL(_raw_write_unlock);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_UNLOCK_IRQRESTORE
+void __lockfunc _raw_write_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
+{
+	__raw_write_unlock_irqrestore(lock, flags);
+}
+EXPORT_SYMBOL(_raw_write_unlock_irqrestore);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_UNLOCK_IRQ
+void __lockfunc _raw_write_unlock_irq(rwlock_t *lock)
+{
+	__raw_write_unlock_irq(lock);
+}
+EXPORT_SYMBOL(_raw_write_unlock_irq);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_UNLOCK_BH
+void __lockfunc _raw_write_unlock_bh(rwlock_t *lock)
+{
+	__raw_write_unlock_bh(lock);
+}
+EXPORT_SYMBOL(_raw_write_unlock_bh);
+#endif
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+
+void __lockfunc _raw_spin_lock_nested(raw_spinlock_t *lock, int subclass)
+{
+	preempt_disable();
+	spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
+	LOCK_CONTENDED(lock, do_raw_spin_trylock, do_raw_spin_lock);
+}
+EXPORT_SYMBOL(_raw_spin_lock_nested);
+
+void __lockfunc _raw_spin_lock_bh_nested(raw_spinlock_t *lock, int subclass)
+{
+	__local_bh_disable_ip(_RET_IP_, SOFTIRQ_LOCK_OFFSET);
+	spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
+	LOCK_CONTENDED(lock, do_raw_spin_trylock, do_raw_spin_lock);
+}
+EXPORT_SYMBOL(_raw_spin_lock_bh_nested);
+
+unsigned long __lockfunc _raw_spin_lock_irqsave_nested(raw_spinlock_t *lock,
+						   int subclass)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	preempt_disable();
+	spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
+	LOCK_CONTENDED_FLAGS(lock, do_raw_spin_trylock, do_raw_spin_lock,
+				do_raw_spin_lock_flags, &flags);
+	return flags;
+}
+EXPORT_SYMBOL(_raw_spin_lock_irqsave_nested);
+
+void __lockfunc _raw_spin_lock_nest_lock(raw_spinlock_t *lock,
+				     struct lockdep_map *nest_lock)
+{
+	preempt_disable();
+	spin_acquire_nest(&lock->dep_map, 0, 0, nest_lock, _RET_IP_);
+	LOCK_CONTENDED(lock, do_raw_spin_trylock, do_raw_spin_lock);
+}
+EXPORT_SYMBOL(_raw_spin_lock_nest_lock);
+
+#endif
+
+notrace int in_lock_functions(unsigned long addr)
+{
+	/* Linker adds these: start and end of __lockfunc functions */
+	extern char __lock_text_start[], __lock_text_end[];
+
+	return addr >= (unsigned long)__lock_text_start
+	&& addr < (unsigned long)__lock_text_end;
+}
+EXPORT_SYMBOL(in_lock_functions);
diff --git a/kernel/locking/spinlock_debug.c b/kernel/locking/spinlock_debug.c
new file mode 100644
index 000000000..0374a596c
--- /dev/null
+++ b/kernel/locking/spinlock_debug.c
@@ -0,0 +1,302 @@
+/*
+ * Copyright 2005, Red Hat, Inc., Ingo Molnar
+ * Released under the General Public License (GPL).
+ *
+ * This file contains the spinlock/rwlock implementations for
+ * DEBUG_SPINLOCK.
+ */
+
+#include <linux/spinlock.h>
+#include <linux/nmi.h>
+#include <linux/interrupt.h>
+#include <linux/debug_locks.h>
+#include <linux/delay.h>
+#include <linux/export.h>
+
+void __raw_spin_lock_init(raw_spinlock_t *lock, const char *name,
+			  struct lock_class_key *key)
+{
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	/*
+	 * Make sure we are not reinitializing a held lock:
+	 */
+	debug_check_no_locks_freed((void *)lock, sizeof(*lock));
+	lockdep_init_map(&lock->dep_map, name, key, 0);
+#endif
+	lock->raw_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
+	lock->magic = SPINLOCK_MAGIC;
+	lock->owner = SPINLOCK_OWNER_INIT;
+	lock->owner_cpu = -1;
+}
+
+EXPORT_SYMBOL(__raw_spin_lock_init);
+
+void __rwlock_init(rwlock_t *lock, const char *name,
+		   struct lock_class_key *key)
+{
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	/*
+	 * Make sure we are not reinitializing a held lock:
+	 */
+	debug_check_no_locks_freed((void *)lock, sizeof(*lock));
+	lockdep_init_map(&lock->dep_map, name, key, 0);
+#endif
+	lock->raw_lock = (arch_rwlock_t) __ARCH_RW_LOCK_UNLOCKED;
+	lock->magic = RWLOCK_MAGIC;
+	lock->owner = SPINLOCK_OWNER_INIT;
+	lock->owner_cpu = -1;
+}
+
+EXPORT_SYMBOL(__rwlock_init);
+
+static void spin_dump(raw_spinlock_t *lock, const char *msg)
+{
+	struct task_struct *owner = NULL;
+
+	if (lock->owner && lock->owner != SPINLOCK_OWNER_INIT)
+		owner = lock->owner;
+	printk(KERN_EMERG "BUG: spinlock %s on CPU#%d, %s/%d\n",
+		msg, raw_smp_processor_id(),
+		current->comm, task_pid_nr(current));
+	printk(KERN_EMERG " lock: %pS, .magic: %08x, .owner: %s/%d, "
+			".owner_cpu: %d\n",
+		lock, lock->magic,
+		owner ? owner->comm : "<none>",
+		owner ? task_pid_nr(owner) : -1,
+		lock->owner_cpu);
+	dump_stack();
+}
+
+static void spin_bug(raw_spinlock_t *lock, const char *msg)
+{
+	if (!debug_locks_off())
+		return;
+
+	spin_dump(lock, msg);
+}
+
+#define SPIN_BUG_ON(cond, lock, msg) if (unlikely(cond)) spin_bug(lock, msg)
+
+static inline void
+debug_spin_lock_before(raw_spinlock_t *lock)
+{
+	SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
+	SPIN_BUG_ON(lock->owner == current, lock, "recursion");
+	SPIN_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
+							lock, "cpu recursion");
+}
+
+static inline void debug_spin_lock_after(raw_spinlock_t *lock)
+{
+	lock->owner_cpu = raw_smp_processor_id();
+	lock->owner = current;
+}
+
+static inline void debug_spin_unlock(raw_spinlock_t *lock)
+{
+	SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
+	SPIN_BUG_ON(!raw_spin_is_locked(lock), lock, "already unlocked");
+	SPIN_BUG_ON(lock->owner != current, lock, "wrong owner");
+	SPIN_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
+							lock, "wrong CPU");
+	lock->owner = SPINLOCK_OWNER_INIT;
+	lock->owner_cpu = -1;
+}
+
+static void __spin_lock_debug(raw_spinlock_t *lock)
+{
+	u64 i;
+	u64 loops = loops_per_jiffy * HZ;
+
+	for (i = 0; i < loops; i++) {
+		if (arch_spin_trylock(&lock->raw_lock))
+			return;
+		__delay(1);
+	}
+	/* lockup suspected: */
+	spin_dump(lock, "lockup suspected");
+#ifdef CONFIG_SMP
+	trigger_all_cpu_backtrace();
+#endif
+
+	/*
+	 * The trylock above was causing a livelock.  Give the lower level arch
+	 * specific lock code a chance to acquire the lock. We have already
+	 * printed a warning/backtrace at this point. The non-debug arch
+	 * specific code might actually succeed in acquiring the lock.  If it is
+	 * not successful, the end-result is the same - there is no forward
+	 * progress.
+	 */
+	arch_spin_lock(&lock->raw_lock);
+}
+
+void do_raw_spin_lock(raw_spinlock_t *lock)
+{
+	debug_spin_lock_before(lock);
+	if (unlikely(!arch_spin_trylock(&lock->raw_lock)))
+		__spin_lock_debug(lock);
+	debug_spin_lock_after(lock);
+}
+
+int do_raw_spin_trylock(raw_spinlock_t *lock)
+{
+	int ret = arch_spin_trylock(&lock->raw_lock);
+
+	if (ret)
+		debug_spin_lock_after(lock);
+#ifndef CONFIG_SMP
+	/*
+	 * Must not happen on UP:
+	 */
+	SPIN_BUG_ON(!ret, lock, "trylock failure on UP");
+#endif
+	return ret;
+}
+
+void do_raw_spin_unlock(raw_spinlock_t *lock)
+{
+	debug_spin_unlock(lock);
+	arch_spin_unlock(&lock->raw_lock);
+}
+
+static void rwlock_bug(rwlock_t *lock, const char *msg)
+{
+	if (!debug_locks_off())
+		return;
+
+	printk(KERN_EMERG "BUG: rwlock %s on CPU#%d, %s/%d, %p\n",
+		msg, raw_smp_processor_id(), current->comm,
+		task_pid_nr(current), lock);
+	dump_stack();
+}
+
+#define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg)
+
+#if 0		/* __write_lock_debug() can lock up - maybe this can too? */
+static void __read_lock_debug(rwlock_t *lock)
+{
+	u64 i;
+	u64 loops = loops_per_jiffy * HZ;
+	int print_once = 1;
+
+	for (;;) {
+		for (i = 0; i < loops; i++) {
+			if (arch_read_trylock(&lock->raw_lock))
+				return;
+			__delay(1);
+		}
+		/* lockup suspected: */
+		if (print_once) {
+			print_once = 0;
+			printk(KERN_EMERG "BUG: read-lock lockup on CPU#%d, "
+					"%s/%d, %p\n",
+				raw_smp_processor_id(), current->comm,
+				current->pid, lock);
+			dump_stack();
+		}
+	}
+}
+#endif
+
+void do_raw_read_lock(rwlock_t *lock)
+{
+	RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
+	arch_read_lock(&lock->raw_lock);
+}
+
+int do_raw_read_trylock(rwlock_t *lock)
+{
+	int ret = arch_read_trylock(&lock->raw_lock);
+
+#ifndef CONFIG_SMP
+	/*
+	 * Must not happen on UP:
+	 */
+	RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
+#endif
+	return ret;
+}
+
+void do_raw_read_unlock(rwlock_t *lock)
+{
+	RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
+	arch_read_unlock(&lock->raw_lock);
+}
+
+static inline void debug_write_lock_before(rwlock_t *lock)
+{
+	RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
+	RWLOCK_BUG_ON(lock->owner == current, lock, "recursion");
+	RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
+							lock, "cpu recursion");
+}
+
+static inline void debug_write_lock_after(rwlock_t *lock)
+{
+	lock->owner_cpu = raw_smp_processor_id();
+	lock->owner = current;
+}
+
+static inline void debug_write_unlock(rwlock_t *lock)
+{
+	RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
+	RWLOCK_BUG_ON(lock->owner != current, lock, "wrong owner");
+	RWLOCK_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
+							lock, "wrong CPU");
+	lock->owner = SPINLOCK_OWNER_INIT;
+	lock->owner_cpu = -1;
+}
+
+#if 0		/* This can cause lockups */
+static void __write_lock_debug(rwlock_t *lock)
+{
+	u64 i;
+	u64 loops = loops_per_jiffy * HZ;
+	int print_once = 1;
+
+	for (;;) {
+		for (i = 0; i < loops; i++) {
+			if (arch_write_trylock(&lock->raw_lock))
+				return;
+			__delay(1);
+		}
+		/* lockup suspected: */
+		if (print_once) {
+			print_once = 0;
+			printk(KERN_EMERG "BUG: write-lock lockup on CPU#%d, "
+					"%s/%d, %p\n",
+				raw_smp_processor_id(), current->comm,
+				current->pid, lock);
+			dump_stack();
+		}
+	}
+}
+#endif
+
+void do_raw_write_lock(rwlock_t *lock)
+{
+	debug_write_lock_before(lock);
+	arch_write_lock(&lock->raw_lock);
+	debug_write_lock_after(lock);
+}
+
+int do_raw_write_trylock(rwlock_t *lock)
+{
+	int ret = arch_write_trylock(&lock->raw_lock);
+
+	if (ret)
+		debug_write_lock_after(lock);
+#ifndef CONFIG_SMP
+	/*
+	 * Must not happen on UP:
+	 */
+	RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
+#endif
+	return ret;
+}
+
+void do_raw_write_unlock(rwlock_t *lock)
+{
+	debug_write_unlock(lock);
+	arch_write_unlock(&lock->raw_lock);
+}