Commit 606a5020 authored by Tejun Heo's avatar Tejun Heo
Browse files

workqueue: gut flush[_delayed]_work_sync() 



Now that all workqueues are non-reentrant, flush[_delayed]_work_sync()
are equivalent to flush[_delayed]_work().  Drop the separate
implementation and make them thin wrappers around
flush[_delayed]_work().

* start_flush_work() no longer takes @wait_executing as the only left
  user - flush_work() - always sets it to %true.

* __cancel_work_timer() uses flush_work() instead of wait_on_work().

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent dbf2576e

include/linux/workqueue.h

+12 −2
Original line number Diff line number Diff line
@@ -412,11 +412,9 @@ 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,
@@ -456,6 +454,18 @@ static inline bool __cancel_delayed_work(struct delayed_work *work) 
	return ret;

}



/* used to be different but now identical to flush_work(), deprecated */

static inline bool flush_work_sync(struct work_struct *work)

{

	return flush_work(work);

}



/* used to be different but now identical to flush_delayed_work(), deprecated */

static inline bool flush_delayed_work_sync(struct delayed_work *dwork)

{

	return flush_delayed_work(dwork);

}



#ifndef CONFIG_SMP

static inline long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)

{

kernel/workqueue.c

+10 −112
Original line number Diff line number Diff line
@@ -2801,8 +2801,7 @@ reflush: 
}

EXPORT_SYMBOL_GPL(drain_workqueue);



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

			     bool wait_executing)

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

{

	struct worker *worker = NULL;

	struct global_cwq *gcwq;
@@ -2824,13 +2823,12 @@ static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr, 
		cwq = get_work_cwq(work);

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

			goto already_gone;

	} else if (wait_executing) {

	} else {

		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);

	spin_unlock_irq(&gcwq->lock);
@@ -2857,15 +2855,8 @@ already_gone: 
 * 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.

 * Wait until @work has finished execution.  @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,
@@ -2878,85 +2869,15 @@ bool flush_work(struct work_struct *work) 
	lock_map_acquire(&work->lockdep_map);

	lock_map_release(&work->lockdep_map);



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

		wait_for_completion(&barr.done);

		destroy_work_on_stack(&barr.work);

		return true;

	} else

		return false;

}

EXPORT_SYMBOL_GPL(flush_work);



static bool wait_on_cpu_work(struct global_cwq *gcwq, struct work_struct *work)

{

	struct wq_barrier barr;

	struct worker *worker;



	spin_lock_irq(&gcwq->lock);



	worker = find_worker_executing_work(gcwq, work);

	if (unlikely(worker))

		insert_wq_barrier(worker->current_cwq, &barr, work, worker);



	spin_unlock_irq(&gcwq->lock);



	if (unlikely(worker)) {

	if (start_flush_work(work, &barr)) {

		wait_for_completion(&barr.done);

		destroy_work_on_stack(&barr.work);

		return true;

	} else

	} else {

		return false;

	}



static bool wait_on_work(struct work_struct *work)

{

	bool ret = false;

	int cpu;



	might_sleep();



	lock_map_acquire(&work->lockdep_map);

	lock_map_release(&work->lockdep_map);



	for_each_gcwq_cpu(cpu)

		ret |= wait_on_cpu_work(get_gcwq(cpu), 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);

EXPORT_SYMBOL_GPL(flush_work);



static bool __cancel_work_timer(struct work_struct *work, bool is_dwork)

{
@@ -2970,14 +2891,14 @@ static bool __cancel_work_timer(struct work_struct *work, bool is_dwork) 
		 * would be waiting for before retrying.

		 */

		if (unlikely(ret == -ENOENT))

			wait_on_work(work);

			flush_work(work);

	} while (unlikely(ret < 0));



	/* tell other tasks trying to grab @work to back off */

	mark_work_canceling(work);

	local_irq_restore(flags);



	wait_on_work(work);

	flush_work(work);

	clear_work_data(work);

	return ret;

}
@@ -3029,29 +2950,6 @@ 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)

{

	local_irq_disable();

	if (del_timer_sync(&dwork->timer))

		__queue_work(dwork->cpu,

			     get_work_cwq(&dwork->work)->wq, &dwork->work);

	local_irq_enable();

	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

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