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authorLinus Torvalds <torvalds@linux-foundation.org>2009-06-10 15:48:53 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-10 15:48:53 -0700
commit082b63ae45e7d14e15995dedd782ec7344596fb2 (patch)
treeb5e52149ecd6ac4a8951abbcf4bef5101bc60479 /kernel
parent99e97b860e14c64760855198e91d1166697131a7 (diff)
parent50fa610a3b6ba7cf91d7a92229177dfaff2b81a1 (diff)
Merge branch 'sched-docs-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'sched-docs-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: sched: Document memory barriers implied by sleep/wake-up primitives
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched.c23
1 files changed, 23 insertions, 0 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 228acae8821f..c3c04e256560 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2464,6 +2464,17 @@ out:
return success;
}
+/**
+ * wake_up_process - Wake up a specific process
+ * @p: The process to be woken up.
+ *
+ * Attempt to wake up the nominated process and move it to the set of runnable
+ * processes. Returns 1 if the process was woken up, 0 if it was already
+ * running.
+ *
+ * It may be assumed that this function implies a write memory barrier before
+ * changing the task state if and only if any tasks are woken up.
+ */
int wake_up_process(struct task_struct *p)
{
return try_to_wake_up(p, TASK_ALL, 0);
@@ -5425,6 +5436,9 @@ static void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
* @mode: which threads
* @nr_exclusive: how many wake-one or wake-many threads to wake up
* @key: is directly passed to the wakeup function
+ *
+ * It may be assumed that this function implies a write memory barrier before
+ * changing the task state if and only if any tasks are woken up.
*/
void __wake_up(wait_queue_head_t *q, unsigned int mode,
int nr_exclusive, void *key)
@@ -5463,6 +5477,9 @@ void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key)
* with each other. This can prevent needless bouncing between CPUs.
*
* On UP it can prevent extra preemption.
+ *
+ * It may be assumed that this function implies a write memory barrier before
+ * changing the task state if and only if any tasks are woken up.
*/
void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode,
int nr_exclusive, void *key)
@@ -5499,6 +5516,9 @@ EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */
* awakened in the same order in which they were queued.
*
* See also complete_all(), wait_for_completion() and related routines.
+ *
+ * It may be assumed that this function implies a write memory barrier before
+ * changing the task state if and only if any tasks are woken up.
*/
void complete(struct completion *x)
{
@@ -5516,6 +5536,9 @@ EXPORT_SYMBOL(complete);
* @x: holds the state of this particular completion
*
* This will wake up all threads waiting on this particular completion event.
+ *
+ * It may be assumed that this function implies a write memory barrier before
+ * changing the task state if and only if any tasks are woken up.
*/
void complete_all(struct completion *x)
{