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workqueue: implement flush[_delayed]_work_sync()

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Implement flush[_delayed]_work_sync().  These are flush functions
which also make sure no CPU is still executing the target work from
earlier queueing instances.  These are similar to
cancel[_delayed]_work_sync() except that the target work item is
flushed instead of cancelled.

Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Tejun Heo 2010-09-16 10:48:29 +02:00
parent baf59022c3
commit 09383498c5
2 changed files with 58 additions and 0 deletions
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2
include/linux/workqueue.h
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@ -355,9 +355,11 @@ extern int keventd_up(void);
int execute_in_process_context(work_func_t fn, struct execute_work *);
extern bool flush_work(struct work_struct *work);
extern bool flush_work_sync(struct work_struct *work);
extern bool cancel_work_sync(struct work_struct *work);
extern bool flush_delayed_work(struct delayed_work *dwork);
extern bool flush_delayed_work_sync(struct delayed_work *work);
extern bool cancel_delayed_work_sync(struct delayed_work *dwork);
extern void workqueue_set_max_active(struct workqueue_struct *wq,

56
kernel/workqueue.c
View File

@ -2435,6 +2435,41 @@ static bool wait_on_work(struct work_struct *work)
return ret;
}
/**
* flush_work_sync - wait until a work has finished execution
* @work: the work to flush
*
* Wait until @work has finished execution. On return, it's
* guaranteed that all queueing instances of @work which happened
* before this function is called are finished. In other words, if
* @work hasn't been requeued since this function was called, @work is
* guaranteed to be idle on return.
*
* RETURNS:
* %true if flush_work_sync() waited for the work to finish execution,
* %false if it was already idle.
*/
bool flush_work_sync(struct work_struct *work)
{
struct wq_barrier barr;
bool pending, waited;
/* we'll wait for executions separately, queue barr only if pending */
pending = start_flush_work(work, &barr, false);
/* wait for executions to finish */
waited = wait_on_work(work);
/* wait for the pending one */
if (pending) {
wait_for_completion(&barr.done);
destroy_work_on_stack(&barr.work);
}
return pending || waited;
}
EXPORT_SYMBOL_GPL(flush_work_sync);
/*
* Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit,
* so this work can't be re-armed in any way.
@ -2538,6 +2573,27 @@ bool flush_delayed_work(struct delayed_work *dwork)
}
EXPORT_SYMBOL(flush_delayed_work);
/**
* flush_delayed_work_sync - wait for a dwork to finish
* @dwork: the delayed work to flush
*
* Delayed timer is cancelled and the pending work is queued for
* execution immediately. Other than timer handling, its behavior
* is identical to flush_work_sync().
*
* RETURNS:
* %true if flush_work_sync() waited for the work to finish execution,
* %false if it was already idle.
*/
bool flush_delayed_work_sync(struct delayed_work *dwork)
{
if (del_timer_sync(&dwork->timer))
__queue_work(raw_smp_processor_id(),
get_work_cwq(&dwork->work)->wq, &dwork->work);
return flush_work_sync(&dwork->work);
}
EXPORT_SYMBOL(flush_delayed_work_sync);
/**
* cancel_delayed_work_sync - cancel a delayed work and wait for it to finish
* @dwork: the delayed work cancel