Initial import

1 files changed, 195 insertions, 0 deletions

diff --git a/include/linux/preempt.h b/include/linux/preempt.h
new file mode 100644
index 000000000..de83b4eb1
--- /dev/null
+++ b/include/linux/preempt.h
@@ -0,0 +1,195 @@
+#ifndef __LINUX_PREEMPT_H
+#define __LINUX_PREEMPT_H
+
+/*
+ * include/linux/preempt.h - macros for accessing and manipulating
+ * preempt_count (used for kernel preemption, interrupt count, etc.)
+ */
+
+#include <linux/linkage.h>
+#include <linux/list.h>
+
+/*
+ * We use the MSB mostly because its available; see <linux/preempt_mask.h> for
+ * the other bits -- can't include that header due to inclusion hell.
+ */
+#define PREEMPT_NEED_RESCHED	0x80000000
+
+#include <asm/preempt.h>
+
+#if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER)
+extern void preempt_count_add(int val);
+extern void preempt_count_sub(int val);
+#define preempt_count_dec_and_test() ({ preempt_count_sub(1); should_resched(); })
+#else
+#define preempt_count_add(val)	__preempt_count_add(val)
+#define preempt_count_sub(val)	__preempt_count_sub(val)
+#define preempt_count_dec_and_test() __preempt_count_dec_and_test()
+#endif
+
+#define __preempt_count_inc() __preempt_count_add(1)
+#define __preempt_count_dec() __preempt_count_sub(1)
+
+#define preempt_count_inc() preempt_count_add(1)
+#define preempt_count_dec() preempt_count_sub(1)
+
+#ifdef CONFIG_PREEMPT_COUNT
+
+#define preempt_disable() \
+do { \
+	preempt_count_inc(); \
+	barrier(); \
+} while (0)
+
+#define sched_preempt_enable_no_resched() \
+do { \
+	barrier(); \
+	preempt_count_dec(); \
+} while (0)
+
+#define preempt_enable_no_resched() sched_preempt_enable_no_resched()
+
+#ifdef CONFIG_PREEMPT
+#define preempt_enable() \
+do { \
+	barrier(); \
+	if (unlikely(preempt_count_dec_and_test())) \
+		__preempt_schedule(); \
+} while (0)
+
+#define preempt_check_resched() \
+do { \
+	if (should_resched()) \
+		__preempt_schedule(); \
+} while (0)
+
+#else
+#define preempt_enable() \
+do { \
+	barrier(); \
+	preempt_count_dec(); \
+} while (0)
+#define preempt_check_resched() do { } while (0)
+#endif
+
+#define preempt_disable_notrace() \
+do { \
+	__preempt_count_inc(); \
+	barrier(); \
+} while (0)
+
+#define preempt_enable_no_resched_notrace() \
+do { \
+	barrier(); \
+	__preempt_count_dec(); \
+} while (0)
+
+#ifdef CONFIG_PREEMPT
+
+#ifndef CONFIG_CONTEXT_TRACKING
+#define __preempt_schedule_context() __preempt_schedule()
+#endif
+
+#define preempt_enable_notrace() \
+do { \
+	barrier(); \
+	if (unlikely(__preempt_count_dec_and_test())) \
+		__preempt_schedule_context(); \
+} while (0)
+#else
+#define preempt_enable_notrace() \
+do { \
+	barrier(); \
+	__preempt_count_dec(); \
+} while (0)
+#endif
+
+#else /* !CONFIG_PREEMPT_COUNT */
+
+/*
+ * Even if we don't have any preemption, we need preempt disable/enable
+ * to be barriers, so that we don't have things like get_user/put_user
+ * that can cause faults and scheduling migrate into our preempt-protected
+ * region.
+ */
+#define preempt_disable()			barrier()
+#define sched_preempt_enable_no_resched()	barrier()
+#define preempt_enable_no_resched()		barrier()
+#define preempt_enable()			barrier()
+#define preempt_check_resched()			do { } while (0)
+
+#define preempt_disable_notrace()		barrier()
+#define preempt_enable_no_resched_notrace()	barrier()
+#define preempt_enable_notrace()		barrier()
+
+#endif /* CONFIG_PREEMPT_COUNT */
+
+#ifdef MODULE
+/*
+ * Modules have no business playing preemption tricks.
+ */
+#undef sched_preempt_enable_no_resched
+#undef preempt_enable_no_resched
+#undef preempt_enable_no_resched_notrace
+#undef preempt_check_resched
+#endif
+
+#define preempt_set_need_resched() \
+do { \
+	set_preempt_need_resched(); \
+} while (0)
+#define preempt_fold_need_resched() \
+do { \
+	if (tif_need_resched()) \
+		set_preempt_need_resched(); \
+} while (0)
+
+#ifdef CONFIG_PREEMPT_NOTIFIERS
+
+struct preempt_notifier;
+
+/**
+ * preempt_ops - notifiers called when a task is preempted and rescheduled
+ * @sched_in: we're about to be rescheduled:
+ *    notifier: struct preempt_notifier for the task being scheduled
+ *    cpu:  cpu we're scheduled on
+ * @sched_out: we've just been preempted
+ *    notifier: struct preempt_notifier for the task being preempted
+ *    next: the task that's kicking us out
+ *
+ * Please note that sched_in and out are called under different
+ * contexts.  sched_out is called with rq lock held and irq disabled
+ * while sched_in is called without rq lock and irq enabled.  This
+ * difference is intentional and depended upon by its users.
+ */
+struct preempt_ops {
+	void (*sched_in)(struct preempt_notifier *notifier, int cpu);
+	void (*sched_out)(struct preempt_notifier *notifier,
+			  struct task_struct *next);
+};
+
+/**
+ * preempt_notifier - key for installing preemption notifiers
+ * @link: internal use
+ * @ops: defines the notifier functions to be called
+ *
+ * Usually used in conjunction with container_of().
+ */
+struct preempt_notifier {
+	struct hlist_node link;
+	struct preempt_ops *ops;
+};
+
+void preempt_notifier_register(struct preempt_notifier *notifier);
+void preempt_notifier_unregister(struct preempt_notifier *notifier);
+
+static inline void preempt_notifier_init(struct preempt_notifier *notifier,
+				     struct preempt_ops *ops)
+{
+	INIT_HLIST_NODE(&notifier->link);
+	notifier->ops = ops;
+}
+
+#endif
+
+#endif /* __LINUX_PREEMPT_H */