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sched: Document wait_for_completion_*() return values

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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>
This commit is contained in:
J. Bruce Fields
2011-10-06 15:22:46 -04:00
committed by Ingo Molnar
parent 461819ac8e
commit c6dc7f055d
1 changed files with 13 additions and 0 deletions
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13
kernel/sched.c
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@@ -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 * 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 * specified timeout to expire. The timeout is in jiffies. It is not
* interruptible. * 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 unsigned long __sched
wait_for_completion_timeout(struct completion *x, unsigned long timeout) 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 * This waits for completion of a specific task to be signaled. It is
* interruptible. * interruptible.
*
* The return value is -ERESTARTSYS if interrupted, 0 if completed.
*/ */
int __sched wait_for_completion_interruptible(struct completion *x) 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 * 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. * 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 long __sched
wait_for_completion_interruptible_timeout(struct completion *x, 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 * This waits to be signaled for completion of a specific task. It can be
* interrupted by a kill signal. * interrupted by a kill signal.
*
* The return value is -ERESTARTSYS if interrupted, 0 if completed.
*/ */
int __sched wait_for_completion_killable(struct completion *x) 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 * This waits for either a completion of a specific task to be
* signaled or for a specified timeout to expire. It can be * signaled or for a specified timeout to expire. It can be
* interrupted by a kill signal. The timeout is in jiffies. * 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 long __sched
wait_for_completion_killable_timeout(struct completion *x, wait_for_completion_killable_timeout(struct completion *x,