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Date: Sun, 11 Feb 2007 00:50:40 +0300
From: Oleg Nesterov <oleg@...sign.ru>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Ingo Molnar <mingo@...e.hu>, David Howells <dhowells@...hat.com>,
Daniel Drake <dsd@...too.org>, linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] 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: Oleg Nesterov <oleg@...sign.ru>
--- 6.20-rc6-mm3/include/linux/workqueue.h~1_dw_fw 2007-02-10 18:15:04.000000000 +0300
+++ 6.20-rc6-mm3/include/linux/workqueue.h 2007-02-10 18:16:15.000000000 +0300
@@ -193,7 +193,7 @@ int execute_in_process_context(work_func
/*
* Kill off a pending schedule_delayed_work(). Note that the work callback
* function may still be running on return from cancel_delayed_work(). Run
- * flush_scheduled_work() or flush_work() to wait on it.
+ * flush_workqueue() or flush_work() to wait on it.
*/
static inline int cancel_delayed_work(struct delayed_work *work)
{
--- 6.20-rc6-mm3/kernel/workqueue.c~1_dw_fw 2007-02-07 23:08:23.000000000 +0300
+++ 6.20-rc6-mm3/kernel/workqueue.c 2007-02-10 18:23:34.000000000 +0300
@@ -90,18 +90,20 @@ static const cpumask_t *wq_cpu_map(struc
* Set the workqueue on which a work item is to be run
* - 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;
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);
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);
}
@@ -157,7 +159,8 @@ EXPORT_SYMBOL_GPL(queue_work);
void delayed_work_timer_fn(unsigned long __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();
if (unlikely(is_single_threaded(wq)))
@@ -189,8 +192,9 @@ int fastcall queue_delayed_work(struct w
BUG_ON(timer_pending(timer));
BUG_ON(!list_empty(&work->entry));
- /* This stores wq for the moment, for the timer_fn */
- set_wq_data(work, wq);
+ /* This stores cwq for the moment, for the timer_fn */
+ set_wq_data(work,
+ per_cpu_ptr(wq->cpu_wq, raw_smp_processor_id()));
timer->expires = jiffies + delay;
timer->data = (unsigned long)dwork;
timer->function = delayed_work_timer_fn;
@@ -221,8 +225,9 @@ int queue_delayed_work_on(int cpu, struc
BUG_ON(timer_pending(timer));
BUG_ON(!list_empty(&work->entry));
- /* This stores wq for the moment, for the timer_fn */
- set_wq_data(work, wq);
+ /* This stores cwq for the moment, for the timer_fn */
+ set_wq_data(work,
+ per_cpu_ptr(wq->cpu_wq, raw_smp_processor_id()));
timer->expires = jiffies + delay;
timer->data = (unsigned long)dwork;
timer->function = delayed_work_timer_fn;
@@ -563,9 +568,12 @@ void flush_work_keventd(struct work_stru
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
* @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,
struct delayed_work *dwork)
@@ -580,7 +588,7 @@ void cancel_rearming_delayed_workqueue(s
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
*/
void cancel_rearming_delayed_work(struct delayed_work *dwork)
-
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