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authorJ. Bruce Fields <bfields@redhat.com>2011-10-06 15:22:46 -0400
committerIngo Molnar <mingo@elte.hu>2011-11-14 12:50:37 +0100
commitc6dc7f055d333ef35f397b8d7c3abcd1918bf8cb (patch)
treec4edc4a84ba9636057d923a308e2a3bcd910fa63 /kernel
parent461819ac8ee950ce027c72a066156a3df9e60c7e (diff)
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sched: Document wait_for_completion_*() return values
The return-value convention for these functions varies depending on whether they're interruptible or can timeout. It can be a little confusing--document it. Signed-off-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20111006192246.GB28026@fieldses.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 0e9344a..3d2c436 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4810,6 +4810,9 @@ EXPORT_SYMBOL(wait_for_completion);
* This waits for either a completion of a specific task to be signaled or for a
* specified timeout to expire. The timeout is in jiffies. It is not
* interruptible.
+ *
+ * The return value is 0 if timed out, and positive (at least 1, or number of
+ * jiffies left till timeout) if completed.
*/
unsigned long __sched
wait_for_completion_timeout(struct completion *x, unsigned long timeout)
@@ -4824,6 +4827,8 @@ EXPORT_SYMBOL(wait_for_completion_timeout);
*
* This waits for completion of a specific task to be signaled. It is
* interruptible.
+ *
+ * The return value is -ERESTARTSYS if interrupted, 0 if completed.
*/
int __sched wait_for_completion_interruptible(struct completion *x)
{
@@ -4841,6 +4846,9 @@ EXPORT_SYMBOL(wait_for_completion_interruptible);
*
* This waits for either a completion of a specific task to be signaled or for a
* specified timeout to expire. It is interruptible. The timeout is in jiffies.
+ *
+ * The return value is -ERESTARTSYS if interrupted, 0 if timed out,
+ * positive (at least 1, or number of jiffies left till timeout) if completed.
*/
long __sched
wait_for_completion_interruptible_timeout(struct completion *x,
@@ -4856,6 +4864,8 @@ EXPORT_SYMBOL(wait_for_completion_interruptible_timeout);
*
* This waits to be signaled for completion of a specific task. It can be
* interrupted by a kill signal.
+ *
+ * The return value is -ERESTARTSYS if interrupted, 0 if completed.
*/
int __sched wait_for_completion_killable(struct completion *x)
{
@@ -4874,6 +4884,9 @@ EXPORT_SYMBOL(wait_for_completion_killable);
* This waits for either a completion of a specific task to be
* signaled or for a specified timeout to expire. It can be
* interrupted by a kill signal. The timeout is in jiffies.
+ *
+ * The return value is -ERESTARTSYS if interrupted, 0 if timed out,
+ * positive (at least 1, or number of jiffies left till timeout) if completed.
*/
long __sched
wait_for_completion_killable_timeout(struct completion *x,
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