From c1a220e7acf8ad2c03504891f4a70cd9c32c904b Mon Sep 17 00:00:00 2001 From: Zhang Rui Date: Wed, 23 Jul 2008 21:28:39 -0700 Subject: pm: introduce new interfaces schedule_work_on() and queue_work_on() This interface allows adding a job on a specific cpu. Although a work struct on a cpu will be scheduled to other cpu if the cpu dies, there is a recursion if a work task tries to offline the cpu it's running on. we need to schedule the task to a specific cpu in this case. http://bugzilla.kernel.org/show_bug.cgi?id=10897 [oleg@tv-sign.ru: cleanups] Signed-off-by: Zhang Rui Tested-by: Rus Signed-off-by: Rafael J. Wysocki Acked-by: Pavel Machek Signed-off-by: Oleg Nesterov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/workqueue.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux/workqueue.h') diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index 542526c6e8ef..14d47120682b 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -179,6 +179,8 @@ __create_workqueue_key(const char *name, int singlethread, extern void destroy_workqueue(struct workqueue_struct *wq); extern int queue_work(struct workqueue_struct *wq, struct work_struct *work); +extern int queue_work_on(int cpu, struct workqueue_struct *wq, + struct work_struct *work); extern int queue_delayed_work(struct workqueue_struct *wq, struct delayed_work *work, unsigned long delay); extern int queue_delayed_work_on(int cpu, struct workqueue_struct *wq, @@ -188,6 +190,7 @@ extern void flush_workqueue(struct workqueue_struct *wq); extern void flush_scheduled_work(void); extern int schedule_work(struct work_struct *work); +extern int schedule_work_on(int cpu, struct work_struct *work); extern int schedule_delayed_work(struct delayed_work *work, unsigned long delay); extern int schedule_delayed_work_on(int cpu, struct delayed_work *work, unsigned long delay); -- cgit v1.2.3 From db700897224b5ebdf852f2d38920ce428940d059 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Fri, 25 Jul 2008 01:47:49 -0700 Subject: workqueues: implement flush_work() Most of users of flush_workqueue() can be changed to use cancel_work_sync(), but sometimes we really need to wait for the completion and cancelling is not an option. schedule_on_each_cpu() is good example. Add the new helper, flush_work(work), which waits for the completion of the specific work_struct. More precisely, it "flushes" the result of of the last queue_work() which is visible to the caller. For example, this code queue_work(wq, work); /* WINDOW */ queue_work(wq, work); flush_work(work); doesn't necessary work "as expected". What can happen in the WINDOW above is - wq starts the execution of work->func() - the caller migrates to another CPU now, after the 2nd queue_work() this work is active on the previous CPU, and at the same time it is queued on another. In this case flush_work(work) may return before the first work->func() completes. It is trivial to add another helper int flush_work_sync(struct work_struct *work) { return flush_work(work) || wait_on_work(work); } which works "more correctly", but it has to iterate over all CPUs and thus it much slower than flush_work(). Signed-off-by: Oleg Nesterov Acked-by: Max Krasnyansky Acked-by: Jarek Poplawski Cc: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/workqueue.h | 2 ++ kernel/workqueue.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 48 insertions(+) (limited to 'include/linux/workqueue.h') diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index 14d47120682b..5c158c477ac7 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -201,6 +201,8 @@ extern int keventd_up(void); extern void init_workqueues(void); int execute_in_process_context(work_func_t fn, struct execute_work *); +extern int flush_work(struct work_struct *work); + extern int cancel_work_sync(struct work_struct *work); /* diff --git a/kernel/workqueue.c b/kernel/workqueue.c index d9a2d65cc63e..ee41cf857d55 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -423,6 +423,52 @@ void flush_workqueue(struct workqueue_struct *wq) } EXPORT_SYMBOL_GPL(flush_workqueue); +/** + * flush_work - block until a work_struct's callback has terminated + * @work: the work which is to be flushed + * + * It is expected that, prior to calling flush_work(), the caller has + * arranged for the work to not be requeued, otherwise it doesn't make + * sense to use this function. + */ +int flush_work(struct work_struct *work) +{ + struct cpu_workqueue_struct *cwq; + struct list_head *prev; + struct wq_barrier barr; + + might_sleep(); + cwq = get_wq_data(work); + if (!cwq) + return 0; + + prev = NULL; + spin_lock_irq(&cwq->lock); + if (!list_empty(&work->entry)) { + /* + * See the comment near try_to_grab_pending()->smp_rmb(). + * If it was re-queued under us we are not going to wait. + */ + smp_rmb(); + if (unlikely(cwq != get_wq_data(work))) + goto out; + prev = &work->entry; + } else { + if (cwq->current_work != work) + goto out; + prev = &cwq->worklist; + } + insert_wq_barrier(cwq, &barr, prev->next); +out: + spin_unlock_irq(&cwq->lock); + if (!prev) + return 0; + + wait_for_completion(&barr.done); + return 1; +} +EXPORT_SYMBOL_GPL(flush_work); + /* * Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit, * so this work can't be re-armed in any way. -- cgit v1.2.3 From 0d557dc97f4bb501f086a03d0f00b99a7855d794 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Mon, 13 Oct 2008 23:50:09 +0200 Subject: workqueue: introduce create_rt_workqueue create_rt_workqueue will create a real time prioritized workqueue. This is needed for the conversion of stop_machine to a workqueue based implementation. This patch adds yet another parameter to __create_workqueue_key to tell it that we want an rt workqueue. However it looks like we rather should have something like "int type" instead of singlethread, freezable and rt. Signed-off-by: Heiko Carstens Signed-off-by: Rusty Russell Cc: Ingo Molnar --- include/linux/workqueue.h | 18 ++++++++++-------- kernel/workqueue.c | 7 ++++++- 2 files changed, 16 insertions(+), 9 deletions(-) (limited to 'include/linux/workqueue.h') diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index 5c158c477ac7..89a5a1231ffb 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -149,11 +149,11 @@ struct execute_work { extern struct workqueue_struct * __create_workqueue_key(const char *name, int singlethread, - int freezeable, struct lock_class_key *key, + int freezeable, int rt, struct lock_class_key *key, const char *lock_name); #ifdef CONFIG_LOCKDEP -#define __create_workqueue(name, singlethread, freezeable) \ +#define __create_workqueue(name, singlethread, freezeable, rt) \ ({ \ static struct lock_class_key __key; \ const char *__lock_name; \ @@ -164,17 +164,19 @@ __create_workqueue_key(const char *name, int singlethread, __lock_name = #name; \ \ __create_workqueue_key((name), (singlethread), \ - (freezeable), &__key, \ + (freezeable), (rt), &__key, \ __lock_name); \ }) #else -#define __create_workqueue(name, singlethread, freezeable) \ - __create_workqueue_key((name), (singlethread), (freezeable), NULL, NULL) +#define __create_workqueue(name, singlethread, freezeable, rt) \ + __create_workqueue_key((name), (singlethread), (freezeable), (rt), \ + NULL, NULL) #endif -#define create_workqueue(name) __create_workqueue((name), 0, 0) -#define create_freezeable_workqueue(name) __create_workqueue((name), 1, 1) -#define create_singlethread_workqueue(name) __create_workqueue((name), 1, 0) +#define create_workqueue(name) __create_workqueue((name), 0, 0, 0) +#define create_rt_workqueue(name) __create_workqueue((name), 0, 0, 1) +#define create_freezeable_workqueue(name) __create_workqueue((name), 1, 1, 0) +#define create_singlethread_workqueue(name) __create_workqueue((name), 1, 0, 0) extern void destroy_workqueue(struct workqueue_struct *wq); diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 714afad46539..f928f2a87b9b 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -62,6 +62,7 @@ struct workqueue_struct { const char *name; int singlethread; int freezeable; /* Freeze threads during suspend */ + int rt; #ifdef CONFIG_LOCKDEP struct lockdep_map lockdep_map; #endif @@ -766,6 +767,7 @@ init_cpu_workqueue(struct workqueue_struct *wq, int cpu) static int create_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu) { + struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 }; struct workqueue_struct *wq = cwq->wq; const char *fmt = is_single_threaded(wq) ? "%s" : "%s/%d"; struct task_struct *p; @@ -781,7 +783,8 @@ static int create_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu) */ if (IS_ERR(p)) return PTR_ERR(p); - + if (cwq->wq->rt) + sched_setscheduler_nocheck(p, SCHED_FIFO, ¶m); cwq->thread = p; return 0; @@ -801,6 +804,7 @@ static void start_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu) struct workqueue_struct *__create_workqueue_key(const char *name, int singlethread, int freezeable, + int rt, struct lock_class_key *key, const char *lock_name) { @@ -822,6 +826,7 @@ struct workqueue_struct *__create_workqueue_key(const char *name, lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); wq->singlethread = singlethread; wq->freezeable = freezeable; + wq->rt = rt; INIT_LIST_HEAD(&wq->list); if (singlethread) { -- cgit v1.2.3