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Commit baf59022 authored by Tejun Heo's avatar Tejun Heo
Browse files

workqueue: factor out start_flush_work() 



Factor out start_flush_work() from flush_work().  start_flush_work()
has @wait_executing argument which controls whether the barrier is
queued only if the work is pending or also if executing.  As
flush_work() needs to wait for execution too, it uses %true.

This commit doesn't cause any behavior difference.  start_flush_work()
will be used to implement flush_work_sync().

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 401a8d04

kernel/workqueue.c

+37 −27
Original line number Diff line number Diff line
@@ -2326,35 +2326,17 @@ out_unlock: 
}

EXPORT_SYMBOL_GPL(flush_workqueue);



/**

 * flush_work - wait for a work to finish executing the last queueing instance

 * @work: the work to flush

 *

 * Wait until @work has finished execution.  This function considers

 * only the last queueing instance of @work.  If @work has been

 * enqueued across different CPUs on a non-reentrant workqueue or on

 * multiple workqueues, @work might still be executing on return on

 * some of the CPUs from earlier queueing.

 *

 * If @work was queued only on a non-reentrant, ordered or unbound

 * workqueue, @work is guaranteed to be idle on return if it hasn't

 * been requeued since flush started.

 *

 * RETURNS:

 * %true if flush_work() waited for the work to finish execution,

 * %false if it was already idle.

 */

bool flush_work(struct work_struct *work)

static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr,

			     bool wait_executing)

{

	struct worker *worker = NULL;

	struct global_cwq *gcwq;

	struct cpu_workqueue_struct *cwq;

	struct wq_barrier barr;



	might_sleep();

	gcwq = get_work_gcwq(work);

	if (!gcwq)

		return 0;

		return false;



	spin_lock_irq(&gcwq->lock);

	if (!list_empty(&work->entry)) {
@@ -2367,24 +2349,52 @@ bool flush_work(struct work_struct *work) 
		cwq = get_work_cwq(work);

		if (unlikely(!cwq || gcwq != cwq->gcwq))

			goto already_gone;

	} else {

	} else if (wait_executing) {

		worker = find_worker_executing_work(gcwq, work);

		if (!worker)

			goto already_gone;

		cwq = worker->current_cwq;

	}

	} else

		goto already_gone;



	insert_wq_barrier(cwq, &barr, work, worker);

	insert_wq_barrier(cwq, barr, work, worker);

	spin_unlock_irq(&gcwq->lock);



	lock_map_acquire(&cwq->wq->lockdep_map);

	lock_map_release(&cwq->wq->lockdep_map);

	return true;

already_gone:

	spin_unlock_irq(&gcwq->lock);

	return false;

}



/**

 * flush_work - wait for a work to finish executing the last queueing instance

 * @work: the work to flush

 *

 * Wait until @work has finished execution.  This function considers

 * only the last queueing instance of @work.  If @work has been

 * enqueued across different CPUs on a non-reentrant workqueue or on

 * multiple workqueues, @work might still be executing on return on

 * some of the CPUs from earlier queueing.

 *

 * If @work was queued only on a non-reentrant, ordered or unbound

 * workqueue, @work is guaranteed to be idle on return if it hasn't

 * been requeued since flush started.

 *

 * RETURNS:

 * %true if flush_work() waited for the work to finish execution,

 * %false if it was already idle.

 */

bool flush_work(struct work_struct *work)

{

	struct wq_barrier barr;



	if (start_flush_work(work, &barr, true)) {

		wait_for_completion(&barr.done);

		destroy_work_on_stack(&barr.work);

		return true;

already_gone:

	spin_unlock_irq(&gcwq->lock);

	} else

		return false;

}

EXPORT_SYMBOL_GPL(flush_work);