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Subject[PATCH] sched: document wait_for_completion_* return values
From
From: J. Bruce Fields <bfields@redhat.com>

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>
---
kernel/sched.c | 13 +++++++++++++
1 files changed, 13 insertions(+), 0 deletions(-)
diff --git a/kernel/sched.c b/kernel/sched.c
index ccacdbd..ee84344 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4690,6 +4690,9 @@ 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)
@@ -4704,6 +4707,8 @@ 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)
{
@@ -4721,6 +4726,9 @@ 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,
@@ -4736,6 +4744,8 @@ 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)
{
@@ -4754,6 +4764,9 @@ 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,
--
1.7.4.1


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