diff options
| -rw-r--r-- | include/linux/workqueue.h | 3 | ||||
| -rw-r--r-- | kernel/workqueue.c | 81 |
2 files changed, 55 insertions, 29 deletions
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index 57b31b3d83b..2be2887c695 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -255,7 +255,7 @@ enum { WQ_HIGHPRI = 1 << 4, /* high priority */ WQ_CPU_INTENSIVE = 1 << 5, /* cpu instensive workqueue */ - WQ_DYING = 1 << 6, /* internal: workqueue is dying */ + WQ_DRAINING = 1 << 6, /* internal: workqueue is draining */ WQ_RESCUER = 1 << 7, /* internal: workqueue has rescuer */ WQ_MAX_ACTIVE = 512, /* I like 512, better ideas? */ @@ -355,6 +355,7 @@ extern int queue_delayed_work_on(int cpu, struct workqueue_struct *wq, struct delayed_work *work, unsigned long delay); extern void flush_workqueue(struct workqueue_struct *wq); +extern void drain_workqueue(struct workqueue_struct *wq); extern void flush_scheduled_work(void); extern int schedule_work(struct work_struct *work); diff --git a/kernel/workqueue.c b/kernel/workqueue.c index e3378e8d3a5..25c8afeaeae 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -221,7 +221,7 @@ typedef unsigned long mayday_mask_t; * per-CPU workqueues: */ struct workqueue_struct { - unsigned int flags; /* I: WQ_* flags */ + unsigned int flags; /* W: WQ_* flags */ union { struct cpu_workqueue_struct __percpu *pcpu; struct cpu_workqueue_struct *single; @@ -240,6 +240,7 @@ struct workqueue_struct { mayday_mask_t mayday_mask; /* cpus requesting rescue */ struct worker *rescuer; /* I: rescue worker */ + int nr_drainers; /* W: drain in progress */ int saved_max_active; /* W: saved cwq max_active */ const char *name; /* I: workqueue name */ #ifdef CONFIG_LOCKDEP @@ -990,7 +991,7 @@ static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, debug_work_activate(work); /* if dying, only works from the same workqueue are allowed */ - if (unlikely(wq->flags & WQ_DYING) && + if (unlikely(wq->flags & WQ_DRAINING) && WARN_ON_ONCE(!is_chained_work(wq))) return; @@ -2381,6 +2382,54 @@ out_unlock: } EXPORT_SYMBOL_GPL(flush_workqueue); +/** + * drain_workqueue - drain a workqueue + * @wq: workqueue to drain + * + * Wait until the workqueue becomes empty. While draining is in progress, + * only chain queueing is allowed. IOW, only currently pending or running + * work items on @wq can queue further work items on it. @wq is flushed + * repeatedly until it becomes empty. The number of flushing is detemined + * by the depth of chaining and should be relatively short. Whine if it + * takes too long. + */ +void drain_workqueue(struct workqueue_struct *wq) +{ + unsigned int flush_cnt = 0; + unsigned int cpu; + + /* + * __queue_work() needs to test whether there are drainers, is much + * hotter than drain_workqueue() and already looks at @wq->flags. + * Use WQ_DRAINING so that queue doesn't have to check nr_drainers. + */ + spin_lock(&workqueue_lock); + if (!wq->nr_drainers++) + wq->flags |= WQ_DRAINING; + spin_unlock(&workqueue_lock); +reflush: + flush_workqueue(wq); + + for_each_cwq_cpu(cpu, wq) { + struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); + + if (!cwq->nr_active && list_empty(&cwq->delayed_works)) + continue; + + if (++flush_cnt == 10 || + (flush_cnt % 100 == 0 && flush_cnt <= 1000)) + pr_warning("workqueue %s: flush on destruction isn't complete after %u tries\n", + wq->name, flush_cnt); + goto reflush; + } + + spin_lock(&workqueue_lock); + if (!--wq->nr_drainers) + wq->flags &= ~WQ_DRAINING; + spin_unlock(&workqueue_lock); +} +EXPORT_SYMBOL_GPL(drain_workqueue); + static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr, bool wait_executing) { @@ -3011,34 +3060,10 @@ EXPORT_SYMBOL_GPL(__alloc_workqueue_key); */ void destroy_workqueue(struct workqueue_struct *wq) { - unsigned int flush_cnt = 0; unsigned int cpu; - /* - * Mark @wq dying and drain all pending works. Once WQ_DYING is - * set, only chain queueing is allowed. IOW, only currently - * pending or running work items on @wq can queue further work - * items on it. @wq is flushed repeatedly until it becomes empty. - * The number of flushing is detemined by the depth of chaining and - * should be relatively short. Whine if it takes too long. - */ - wq->flags |= WQ_DYING; -reflush: - flush_workqueue(wq); - - for_each_cwq_cpu(cpu, wq) { - struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); - - if (!cwq->nr_active && list_empty(&cwq->delayed_works)) - continue; - - if (++flush_cnt == 10 || - (flush_cnt % 100 == 0 && flush_cnt <= 1000)) - printk(KERN_WARNING "workqueue %s: flush on " - "destruction isn't complete after %u tries\n", - wq->name, flush_cnt); - goto reflush; - } + /* drain it before proceeding with destruction */ + drain_workqueue(wq); /* * wq list is used to freeze wq, remove from list after |