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wait: add wait_event_cmd() 

Add a new API wait_event_cmd(). It's a variant of wait_even() with two
commands executed. One is executed before sleep, another after sleep.

Modified to match use wait.h approach based on suggestion by
Peter Zijlstra <peterz@infradead.org> - neilb

Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
Shaohua Li 2013-11-14 15:16:16 +11:00 committed by NeilBrown
parent ba8805b973
commit 82e06c8111
1 changed files with 25 additions and 0 deletions
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25
include/linux/wait.h
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@ -278,6 +278,31 @@ do { \
__ret; \
})
#define __wait_event_cmd(wq, condition, cmd1, cmd2) \
(void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0, \
cmd1; schedule(); cmd2)
/**
* wait_event_cmd - sleep until a condition gets true
* @wq: the waitqueue to wait on
* @condition: a C expression for the event to wait for
* cmd1: the command will be executed before sleep
* cmd2: the command will be executed after sleep
*
* The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
* @condition evaluates to true. The @condition is checked each time
* the waitqueue @wq is woken up.
*
* wake_up() has to be called after changing any variable that could
* change the result of the wait condition.
*/
#define wait_event_cmd(wq, condition, cmd1, cmd2) \
do { \
if (condition) \
break; \
__wait_event_cmd(wq, condition, cmd1, cmd2); \
} while (0)
#define __wait_event_interruptible(wq, condition) \
___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0, \
schedule())