[tip:sched/core] sched: Document wait_for_completion_*() return values

[tip-bot for J. Bruce Fields]

Commit-ID:  c6dc7f055d333ef35f397b8d7c3abcd1918bf8cb
Gitweb:     http://git.kernel.org/tip/c6dc7f055d333ef35f397b8d7c3abcd1918bf8cb
Author:     J. Bruce Fields <bfields@xxxxxxxxxx>
AuthorDate: Thu, 6 Oct 2011 15:22:46 -0400
Committer:  Ingo Molnar <mingo@xxxxxxx>
CommitDate: Mon, 14 Nov 2011 12:50:37 +0100

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@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: http://lkml.kernel.org/r/20111006192246.GB28026@xxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
 kernel/sched.c |   13 +++++++++++++
 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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