Initial import

1 files changed, 178 insertions, 0 deletions

diff --git a/include/linux/mutex.h b/include/linux/mutex.h
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+++ b/include/linux/mutex.h
@@ -0,0 +1,178 @@
+/*
+ * 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 the main data structure and API definitions.
+ */
+#ifndef __LINUX_MUTEX_H
+#define __LINUX_MUTEX_H
+
+#include <asm/current.h>
+#include <linux/list.h>
+#include <linux/spinlock_types.h>
+#include <linux/linkage.h>
+#include <linux/lockdep.h>
+#include <linux/atomic.h>
+#include <asm/processor.h>
+#include <linux/osq_lock.h>
+
+/*
+ * Simple, straightforward mutexes with strict semantics:
+ *
+ * - only one task can hold the mutex at a time
+ * - only the owner can unlock the mutex
+ * - multiple unlocks are not permitted
+ * - recursive locking is not permitted
+ * - a mutex object must be initialized via the API
+ * - a mutex object must not be initialized via memset or copying
+ * - task may not exit with mutex held
+ * - memory areas where held locks reside must not be freed
+ * - held mutexes must not be reinitialized
+ * - mutexes may not be used in hardware or software interrupt
+ *   contexts such as tasklets and timers
+ *
+ * These semantics are fully enforced when DEBUG_MUTEXES is
+ * enabled. Furthermore, besides enforcing the above rules, the mutex
+ * debugging code also implements a number of additional features
+ * that make lock debugging easier and faster:
+ *
+ * - uses symbolic names of mutexes, whenever they are printed in debug output
+ * - point-of-acquire tracking, symbolic lookup of function names
+ * - list of all locks held in the system, printout of them
+ * - owner tracking
+ * - detects self-recursing locks and prints out all relevant info
+ * - detects multi-task circular deadlocks and prints out all affected
+ *   locks and tasks (and only those tasks)
+ */
+struct mutex {
+	/* 1: unlocked, 0: locked, negative: locked, possible waiters */
+	atomic_t		count;
+	spinlock_t		wait_lock;
+	struct list_head	wait_list;
+#if defined(CONFIG_DEBUG_MUTEXES) || defined(CONFIG_MUTEX_SPIN_ON_OWNER)
+	struct task_struct	*owner;
+#endif
+#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
+	struct optimistic_spin_queue osq; /* Spinner MCS lock */
+#endif
+#ifdef CONFIG_DEBUG_MUTEXES
+	void			*magic;
+#endif
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	struct lockdep_map	dep_map;
+#endif
+};
+
+/*
+ * This is the control structure for tasks blocked on mutex,
+ * which resides on the blocked task's kernel stack:
+ */
+struct mutex_waiter {
+	struct list_head	list;
+	struct task_struct	*task;
+#ifdef CONFIG_DEBUG_MUTEXES
+	void			*magic;
+#endif
+};
+
+#ifdef CONFIG_DEBUG_MUTEXES
+# include <linux/mutex-debug.h>
+#else
+# define __DEBUG_MUTEX_INITIALIZER(lockname)
+/**
+ * mutex_init - initialize the mutex
+ * @mutex: the mutex to be initialized
+ *
+ * Initialize the mutex to unlocked state.
+ *
+ * It is not allowed to initialize an already locked mutex.
+ */
+# define mutex_init(mutex) \
+do {							\
+	static struct lock_class_key __key;		\
+							\
+	__mutex_init((mutex), #mutex, &__key);		\
+} while (0)
+static inline void mutex_destroy(struct mutex *lock) {}
+#endif
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+# define __DEP_MAP_MUTEX_INITIALIZER(lockname) \
+		, .dep_map = { .name = #lockname }
+#else
+# define __DEP_MAP_MUTEX_INITIALIZER(lockname)
+#endif
+
+#define __MUTEX_INITIALIZER(lockname) \
+		{ .count = ATOMIC_INIT(1) \
+		, .wait_lock = __SPIN_LOCK_UNLOCKED(lockname.wait_lock) \
+		, .wait_list = LIST_HEAD_INIT(lockname.wait_list) \
+		__DEBUG_MUTEX_INITIALIZER(lockname) \
+		__DEP_MAP_MUTEX_INITIALIZER(lockname) }
+
+#define DEFINE_MUTEX(mutexname) \
+	struct mutex mutexname = __MUTEX_INITIALIZER(mutexname)
+
+extern void __mutex_init(struct mutex *lock, const char *name,
+			 struct lock_class_key *key);
+
+/**
+ * mutex_is_locked - is the mutex locked
+ * @lock: the mutex to be queried
+ *
+ * Returns 1 if the mutex is locked, 0 if unlocked.
+ */
+static inline int mutex_is_locked(struct mutex *lock)
+{
+	return atomic_read(&lock->count) != 1;
+}
+
+/*
+ * See kernel/locking/mutex.c for detailed documentation of these APIs.
+ * Also see Documentation/locking/mutex-design.txt.
+ */
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass);
+extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock);
+
+extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock,
+					unsigned int subclass);
+extern int __must_check mutex_lock_killable_nested(struct mutex *lock,
+					unsigned int subclass);
+
+#define mutex_lock(lock) mutex_lock_nested(lock, 0)
+#define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0)
+#define mutex_lock_killable(lock) mutex_lock_killable_nested(lock, 0)
+
+#define mutex_lock_nest_lock(lock, nest_lock)				\
+do {									\
+	typecheck(struct lockdep_map *, &(nest_lock)->dep_map);	\
+	_mutex_lock_nest_lock(lock, &(nest_lock)->dep_map);		\
+} while (0)
+
+#else
+extern void mutex_lock(struct mutex *lock);
+extern int __must_check mutex_lock_interruptible(struct mutex *lock);
+extern int __must_check mutex_lock_killable(struct mutex *lock);
+
+# define mutex_lock_nested(lock, subclass) mutex_lock(lock)
+# define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock)
+# define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock)
+# define mutex_lock_nest_lock(lock, nest_lock) mutex_lock(lock)
+#endif
+
+/*
+ * NOTE: mutex_trylock() follows the spin_trylock() convention,
+ *       not the down_trylock() convention!
+ *
+ * Returns 1 if the mutex has been acquired successfully, and 0 on contention.
+ */
+extern int mutex_trylock(struct mutex *lock);
+extern void mutex_unlock(struct mutex *lock);
+
+extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);
+
+#endif /* __LINUX_MUTEX_H */