diff options
Diffstat (limited to 'kernel/workqueue.c')
| -rw-r--r-- | kernel/workqueue.c | 163 |
1 files changed, 153 insertions, 10 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index e541b5db67dd..4d059c532792 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -78,7 +78,7 @@ struct cpu_workqueue_struct { int nr_in_flight[WORK_NR_COLORS]; /* L: nr of in_flight works */ int nr_active; /* L: nr of active works */ - int max_active; /* I: max active works */ + int max_active; /* L: max active works */ struct list_head delayed_works; /* L: delayed works */ }; @@ -108,6 +108,7 @@ struct workqueue_struct { struct list_head flusher_queue; /* F: flush waiters */ struct list_head flusher_overflow; /* F: flush overflow list */ + int saved_max_active; /* I: saved cwq max_active */ const char *name; /* I: workqueue name */ #ifdef CONFIG_LOCKDEP struct lockdep_map lockdep_map; @@ -228,6 +229,7 @@ static inline void debug_work_deactivate(struct work_struct *work) { } static DEFINE_SPINLOCK(workqueue_lock); static LIST_HEAD(workqueues); static DEFINE_PER_CPU(struct ida, worker_ida); +static bool workqueue_freezing; /* W: have wqs started freezing? */ static int worker_thread(void *__worker); @@ -745,19 +747,13 @@ static int worker_thread(void *__worker) struct cpu_workqueue_struct *cwq = worker->cwq; DEFINE_WAIT(wait); - if (cwq->wq->flags & WQ_FREEZEABLE) - set_freezable(); - for (;;) { prepare_to_wait(&cwq->more_work, &wait, TASK_INTERRUPTIBLE); - if (!freezing(current) && - !kthread_should_stop() && + if (!kthread_should_stop() && list_empty(&cwq->worklist)) schedule(); finish_wait(&cwq->more_work, &wait); - try_to_freeze(); - if (kthread_should_stop()) break; @@ -1553,6 +1549,7 @@ struct workqueue_struct *__create_workqueue_key(const char *name, goto err; wq->flags = flags; + wq->saved_max_active = max_active; mutex_init(&wq->flush_mutex); atomic_set(&wq->nr_cwqs_to_flush, 0); INIT_LIST_HEAD(&wq->flusher_queue); @@ -1591,8 +1588,19 @@ struct workqueue_struct *__create_workqueue_key(const char *name, failed = true; } + /* + * workqueue_lock protects global freeze state and workqueues + * list. Grab it, set max_active accordingly and add the new + * workqueue to workqueues list. + */ spin_lock(&workqueue_lock); + + if (workqueue_freezing && wq->flags & WQ_FREEZEABLE) + for_each_possible_cpu(cpu) + get_cwq(cpu, wq)->max_active = 0; + list_add(&wq->list, &workqueues); + spin_unlock(&workqueue_lock); cpu_maps_update_done(); @@ -1621,14 +1629,18 @@ void destroy_workqueue(struct workqueue_struct *wq) { int cpu; + flush_workqueue(wq); + + /* + * wq list is used to freeze wq, remove from list after + * flushing is complete in case freeze races us. + */ cpu_maps_update_begin(); spin_lock(&workqueue_lock); list_del(&wq->list); spin_unlock(&workqueue_lock); cpu_maps_update_done(); - flush_workqueue(wq); - for_each_possible_cpu(cpu) { struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); int i; @@ -1722,6 +1734,137 @@ long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) EXPORT_SYMBOL_GPL(work_on_cpu); #endif /* CONFIG_SMP */ +#ifdef CONFIG_FREEZER + +/** + * freeze_workqueues_begin - begin freezing workqueues + * + * Start freezing workqueues. After this function returns, all + * freezeable workqueues will queue new works to their frozen_works + * list instead of the cwq ones. + * + * CONTEXT: + * Grabs and releases workqueue_lock and cwq->lock's. + */ +void freeze_workqueues_begin(void) +{ + struct workqueue_struct *wq; + unsigned int cpu; + + spin_lock(&workqueue_lock); + + BUG_ON(workqueue_freezing); + workqueue_freezing = true; + + for_each_possible_cpu(cpu) { + list_for_each_entry(wq, &workqueues, list) { + struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); + + spin_lock_irq(&cwq->lock); + + if (wq->flags & WQ_FREEZEABLE) + cwq->max_active = 0; + + spin_unlock_irq(&cwq->lock); + } + } + + spin_unlock(&workqueue_lock); +} + +/** + * freeze_workqueues_busy - are freezeable workqueues still busy? + * + * Check whether freezing is complete. This function must be called + * between freeze_workqueues_begin() and thaw_workqueues(). + * + * CONTEXT: + * Grabs and releases workqueue_lock. + * + * RETURNS: + * %true if some freezeable workqueues are still busy. %false if + * freezing is complete. + */ +bool freeze_workqueues_busy(void) +{ + struct workqueue_struct *wq; + unsigned int cpu; + bool busy = false; + + spin_lock(&workqueue_lock); + + BUG_ON(!workqueue_freezing); + + for_each_possible_cpu(cpu) { + /* + * nr_active is monotonically decreasing. It's safe + * to peek without lock. + */ + list_for_each_entry(wq, &workqueues, list) { + struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); + + if (!(wq->flags & WQ_FREEZEABLE)) + continue; + + BUG_ON(cwq->nr_active < 0); + if (cwq->nr_active) { + busy = true; + goto out_unlock; + } + } + } +out_unlock: + spin_unlock(&workqueue_lock); + return busy; +} + +/** + * thaw_workqueues - thaw workqueues + * + * Thaw workqueues. Normal queueing is restored and all collected + * frozen works are transferred to their respective cwq worklists. + * + * CONTEXT: + * Grabs and releases workqueue_lock and cwq->lock's. + */ +void thaw_workqueues(void) +{ + struct workqueue_struct *wq; + unsigned int cpu; + + spin_lock(&workqueue_lock); + + if (!workqueue_freezing) + goto out_unlock; + + for_each_possible_cpu(cpu) { + list_for_each_entry(wq, &workqueues, list) { + struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); + + if (!(wq->flags & WQ_FREEZEABLE)) + continue; + + spin_lock_irq(&cwq->lock); + + /* restore max_active and repopulate worklist */ + cwq->max_active = wq->saved_max_active; + + while (!list_empty(&cwq->delayed_works) && + cwq->nr_active < cwq->max_active) + cwq_activate_first_delayed(cwq); + + wake_up(&cwq->more_work); + + spin_unlock_irq(&cwq->lock); + } + } + + workqueue_freezing = false; +out_unlock: + spin_unlock(&workqueue_lock); +} +#endif /* CONFIG_FREEZER */ + void __init init_workqueues(void) { unsigned int cpu; |