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sched/completion: Document when to use wait_for_completion_io_*()

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As discussed in [1], accounting IO is meant for blkio only. Document that
so driver authors won't use them for device io.

 [1] http://thread.gmane.org/gmane.linux.drivers.i2c/20470

Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1415098901-2768-1-git-send-email-wsa@the-dreams.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Wolfram Sang 2014-11-04 12:01:41 +01:00 committed by Ingo Molnar
parent f622b429da
commit a1bd537335
1 changed files with 3 additions and 2 deletions
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5
kernel/sched/completion.c
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@ -148,7 +148,7 @@ EXPORT_SYMBOL(wait_for_completion_timeout);
*
* This waits to be signaled for completion of a specific task. It is NOT
* interruptible and there is no timeout. The caller is accounted as waiting
* for IO.
* for IO (which traditionally means blkio only).
*/
void __sched wait_for_completion_io(struct completion *x)
{
@ -163,7 +163,8 @@ EXPORT_SYMBOL(wait_for_completion_io);
*
* 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 caller is accounted as waiting for IO.
* interruptible. The caller is accounted as waiting for IO (which traditionally
* means blkio only).
*
* Return: 0 if timed out, and positive (at least 1, or number of jiffies left
* till timeout) if completed.