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make queue_delayed_work() friendly to flush_fork()

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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: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2007-05-09 02:34:16 -07:00 committed by Linus Torvalds
parent 06ba38a9a0
commit ed7c0feede
1 changed files with 18 additions and 10 deletions
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28
kernel/workqueue.c
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@ -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)