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Commit ed7c0fee authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
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make queue_delayed_work() friendly to flush_fork() 



Currently typeof(delayed_work->work.data) is

	"struct workqueue_struct" when the timer is pending

	"struct cpu_workqueue_struct" whe the work is queued

This makes impossible to use flush_fork(delayed_work->work) in addition
to cancel_delayed_work/cancel_rearming_delayed_work, not good.

Change queue_delayed_work/delayed_work_timer_fn to use cwq, not wq. This
complicates (and uglifies) these functions a little bit, but alows us to
use flush_fork(dwork) and imho makes the whole code more consistent.

Also, document the fact that cancel_rearming_delayed_work() doesn't garantee
the completion of work->func() upon return.

Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 06ba38a9

kernel/workqueue.c

+18 −10
Original line number Original line Diff line number Diff line
@@ -90,18 +90,20 @@ static const cpumask_t *wq_cpu_map(struct workqueue_struct *wq) 
 * Set the workqueue on which a work item is to be run

 * Set the workqueue on which a work item is to be run

 * - Must *only* be called if the pending flag is set

 * - Must *only* be called if the pending flag is set

 */

 */

static inline void set_wq_data(struct work_struct *work, void *wq)

static inline void set_wq_data(struct work_struct *work,

				struct cpu_workqueue_struct *cwq)

{

{

	unsigned long new;

	unsigned long new;





	BUG_ON(!work_pending(work));

	BUG_ON(!work_pending(work));





	new = (unsigned long) wq | (1UL << WORK_STRUCT_PENDING);

	new = (unsigned long) cwq | (1UL << WORK_STRUCT_PENDING);

	new |= WORK_STRUCT_FLAG_MASK & *work_data_bits(work);

	new |= WORK_STRUCT_FLAG_MASK & *work_data_bits(work);

	atomic_long_set(&work->data, new);

	atomic_long_set(&work->data, new);

}

}





static inline void *get_wq_data(struct work_struct *work)

static inline

struct cpu_workqueue_struct *get_wq_data(struct work_struct *work)

{

{

	return (void *) (atomic_long_read(&work->data) & WORK_STRUCT_WQ_DATA_MASK);

	return (void *) (atomic_long_read(&work->data) & WORK_STRUCT_WQ_DATA_MASK);

}

}
@@ -157,7 +159,8 @@ EXPORT_SYMBOL_GPL(queue_work); 
void delayed_work_timer_fn(unsigned long __data)

void delayed_work_timer_fn(unsigned long __data)

{

{

	struct delayed_work *dwork = (struct delayed_work *)__data;

	struct delayed_work *dwork = (struct delayed_work *)__data;

	struct workqueue_struct *wq = get_wq_data(&dwork->work);

	struct cpu_workqueue_struct *cwq = get_wq_data(&dwork->work);

	struct workqueue_struct *wq = cwq->wq;

	int cpu = smp_processor_id();

	int cpu = smp_processor_id();





	if (unlikely(is_single_threaded(wq)))

	if (unlikely(is_single_threaded(wq)))
@@ -189,8 +192,9 @@ int fastcall queue_delayed_work(struct workqueue_struct *wq, 
		BUG_ON(timer_pending(timer));

		BUG_ON(timer_pending(timer));

		BUG_ON(!list_empty(&work->entry));

		BUG_ON(!list_empty(&work->entry));





		/* This stores wq for the moment, for the timer_fn */

		/* This stores cwq for the moment, for the timer_fn */

		set_wq_data(work, wq);

		set_wq_data(work,

			per_cpu_ptr(wq->cpu_wq, raw_smp_processor_id()));

		timer->expires = jiffies + delay;

		timer->expires = jiffies + delay;

		timer->data = (unsigned long)dwork;

		timer->data = (unsigned long)dwork;

		timer->function = delayed_work_timer_fn;

		timer->function = delayed_work_timer_fn;
@@ -221,8 +225,9 @@ int queue_delayed_work_on(int cpu, struct workqueue_struct *wq, 
		BUG_ON(timer_pending(timer));

		BUG_ON(timer_pending(timer));

		BUG_ON(!list_empty(&work->entry));

		BUG_ON(!list_empty(&work->entry));





		/* This stores wq for the moment, for the timer_fn */

		/* This stores cwq for the moment, for the timer_fn */

		set_wq_data(work, wq);

		set_wq_data(work,

			per_cpu_ptr(wq->cpu_wq, raw_smp_processor_id()));

		timer->expires = jiffies + delay;

		timer->expires = jiffies + delay;

		timer->data = (unsigned long)dwork;

		timer->data = (unsigned long)dwork;

		timer->function = delayed_work_timer_fn;

		timer->function = delayed_work_timer_fn;
@@ -562,9 +567,12 @@ void flush_work_keventd(struct work_struct *work) 
EXPORT_SYMBOL(flush_work_keventd);

EXPORT_SYMBOL(flush_work_keventd);





/**

/**

 * cancel_rearming_delayed_workqueue - reliably kill off a delayed work whose handler rearms the delayed work.

 * cancel_rearming_delayed_workqueue - kill off a delayed work whose handler rearms the delayed work.

 * @wq:   the controlling workqueue structure

 * @wq:   the controlling workqueue structure

 * @dwork: the delayed work struct

 * @dwork: the delayed work struct

 *

 * Note that the work callback function may still be running on return from

 * cancel_delayed_work(). Run flush_workqueue() or flush_work() to wait on it.

 */

 */

void cancel_rearming_delayed_workqueue(struct workqueue_struct *wq,

void cancel_rearming_delayed_workqueue(struct workqueue_struct *wq,

				       struct delayed_work *dwork)

				       struct delayed_work *dwork)
@@ -579,7 +587,7 @@ void cancel_rearming_delayed_workqueue(struct workqueue_struct *wq, 
EXPORT_SYMBOL(cancel_rearming_delayed_workqueue);

EXPORT_SYMBOL(cancel_rearming_delayed_workqueue);





/**

/**

 * cancel_rearming_delayed_work - reliably kill off a delayed keventd work whose handler rearms the delayed work.

 * cancel_rearming_delayed_work - kill off a delayed keventd work whose handler rearms the delayed work.

 * @dwork: the delayed work struct

 * @dwork: the delayed work struct

 */

 */

void cancel_rearming_delayed_work(struct delayed_work *dwork)

void cancel_rearming_delayed_work(struct delayed_work *dwork)