diff options
Diffstat (limited to 'kernel/workqueue.c')
| -rw-r--r-- | kernel/workqueue.c | 1234 |
1 files changed, 681 insertions, 553 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 692d97628a10..d951daa0ca9a 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -58,7 +58,7 @@ enum { * be executing on any CPU. The gcwq behaves as an unbound one. * * Note that DISASSOCIATED can be flipped only while holding - * managership of all pools on the gcwq to avoid changing binding + * assoc_mutex of all pools on the gcwq to avoid changing binding * state while create_worker() is in progress. */ GCWQ_DISASSOCIATED = 1 << 0, /* cpu can't serve workers */ @@ -66,17 +66,17 @@ enum { /* pool flags */ POOL_MANAGE_WORKERS = 1 << 0, /* need to manage workers */ + POOL_MANAGING_WORKERS = 1 << 1, /* managing workers */ /* worker flags */ WORKER_STARTED = 1 << 0, /* started */ WORKER_DIE = 1 << 1, /* die die die */ WORKER_IDLE = 1 << 2, /* is idle */ WORKER_PREP = 1 << 3, /* preparing to run works */ - WORKER_REBIND = 1 << 5, /* mom is home, come back */ WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ WORKER_UNBOUND = 1 << 7, /* worker is unbound */ - WORKER_NOT_RUNNING = WORKER_PREP | WORKER_REBIND | WORKER_UNBOUND | + WORKER_NOT_RUNNING = WORKER_PREP | WORKER_UNBOUND | WORKER_CPU_INTENSIVE, NR_WORKER_POOLS = 2, /* # worker pools per gcwq */ @@ -125,7 +125,6 @@ enum { struct global_cwq; struct worker_pool; -struct idle_rebind; /* * The poor guys doing the actual heavy lifting. All on-duty workers @@ -149,7 +148,6 @@ struct worker { int id; /* I: worker id */ /* for rebinding worker to CPU */ - struct idle_rebind *idle_rebind; /* L: for idle worker */ struct work_struct rebind_work; /* L: for busy worker */ }; @@ -159,13 +157,15 @@ struct worker_pool { struct list_head worklist; /* L: list of pending works */ int nr_workers; /* L: total number of workers */ + + /* nr_idle includes the ones off idle_list for rebinding */ int nr_idle; /* L: currently idle ones */ struct list_head idle_list; /* X: list of idle workers */ struct timer_list idle_timer; /* L: worker idle timeout */ struct timer_list mayday_timer; /* L: SOS timer for workers */ - struct mutex manager_mutex; /* mutex manager should hold */ + struct mutex assoc_mutex; /* protect GCWQ_DISASSOCIATED */ struct ida worker_ida; /* L: for worker IDs */ }; @@ -183,9 +183,8 @@ struct global_cwq { struct hlist_head busy_hash[BUSY_WORKER_HASH_SIZE]; /* L: hash of busy workers */ - struct worker_pool pools[2]; /* normal and highpri pools */ - - wait_queue_head_t rebind_hold; /* rebind hold wait */ + struct worker_pool pools[NR_WORKER_POOLS]; + /* normal and highpri pools */ } ____cacheline_aligned_in_smp; /* @@ -268,17 +267,15 @@ struct workqueue_struct { }; struct workqueue_struct *system_wq __read_mostly; -struct workqueue_struct *system_long_wq __read_mostly; -struct workqueue_struct *system_nrt_wq __read_mostly; -struct workqueue_struct *system_unbound_wq __read_mostly; -struct workqueue_struct *system_freezable_wq __read_mostly; -struct workqueue_struct *system_nrt_freezable_wq __read_mostly; EXPORT_SYMBOL_GPL(system_wq); +struct workqueue_struct *system_highpri_wq __read_mostly; +EXPORT_SYMBOL_GPL(system_highpri_wq); +struct workqueue_struct *system_long_wq __read_mostly; EXPORT_SYMBOL_GPL(system_long_wq); -EXPORT_SYMBOL_GPL(system_nrt_wq); +struct workqueue_struct *system_unbound_wq __read_mostly; EXPORT_SYMBOL_GPL(system_unbound_wq); +struct workqueue_struct *system_freezable_wq __read_mostly; EXPORT_SYMBOL_GPL(system_freezable_wq); -EXPORT_SYMBOL_GPL(system_nrt_freezable_wq); #define CREATE_TRACE_POINTS #include <trace/events/workqueue.h> @@ -533,18 +530,24 @@ static int work_next_color(int color) } /* - * A work's data points to the cwq with WORK_STRUCT_CWQ set while the - * work is on queue. Once execution starts, WORK_STRUCT_CWQ is - * cleared and the work data contains the cpu number it was last on. + * While queued, %WORK_STRUCT_CWQ is set and non flag bits of a work's data + * contain the pointer to the queued cwq. Once execution starts, the flag + * is cleared and the high bits contain OFFQ flags and CPU number. * - * set_work_{cwq|cpu}() and clear_work_data() can be used to set the - * cwq, cpu or clear work->data. These functions should only be - * called while the work is owned - ie. while the PENDING bit is set. + * set_work_cwq(), set_work_cpu_and_clear_pending(), mark_work_canceling() + * and clear_work_data() can be used to set the cwq, cpu or clear + * work->data. These functions should only be called while the work is + * owned - ie. while the PENDING bit is set. * - * get_work_[g]cwq() can be used to obtain the gcwq or cwq - * corresponding to a work. gcwq is available once the work has been - * queued anywhere after initialization. cwq is available only from - * queueing until execution starts. + * get_work_[g]cwq() can be used to obtain the gcwq or cwq corresponding to + * a work. gcwq is available once the work has been queued anywhere after + * initialization until it is sync canceled. cwq is available only while + * the work item is queued. + * + * %WORK_OFFQ_CANCELING is used to mark a work item which is being + * canceled. While being canceled, a work item may have its PENDING set + * but stay off timer and worklist for arbitrarily long and nobody should + * try to steal the PENDING bit. */ static inline void set_work_data(struct work_struct *work, unsigned long data, unsigned long flags) @@ -561,13 +564,22 @@ static void set_work_cwq(struct work_struct *work, WORK_STRUCT_PENDING | WORK_STRUCT_CWQ | extra_flags); } -static void set_work_cpu(struct work_struct *work, unsigned int cpu) +static void set_work_cpu_and_clear_pending(struct work_struct *work, + unsigned int cpu) { - set_work_data(work, cpu << WORK_STRUCT_FLAG_BITS, WORK_STRUCT_PENDING); + /* + * The following wmb is paired with the implied mb in + * test_and_set_bit(PENDING) and ensures all updates to @work made + * here are visible to and precede any updates by the next PENDING + * owner. + */ + smp_wmb(); + set_work_data(work, (unsigned long)cpu << WORK_OFFQ_CPU_SHIFT, 0); } static void clear_work_data(struct work_struct *work) { + smp_wmb(); /* see set_work_cpu_and_clear_pending() */ set_work_data(work, WORK_STRUCT_NO_CPU, 0); } @@ -590,7 +602,7 @@ static struct global_cwq *get_work_gcwq(struct work_struct *work) return ((struct cpu_workqueue_struct *) (data & WORK_STRUCT_WQ_DATA_MASK))->pool->gcwq; - cpu = data >> WORK_STRUCT_FLAG_BITS; + cpu = data >> WORK_OFFQ_CPU_SHIFT; if (cpu == WORK_CPU_NONE) return NULL; @@ -598,6 +610,22 @@ static struct global_cwq *get_work_gcwq(struct work_struct *work) return get_gcwq(cpu); } +static void mark_work_canceling(struct work_struct *work) +{ + struct global_cwq *gcwq = get_work_gcwq(work); + unsigned long cpu = gcwq ? gcwq->cpu : WORK_CPU_NONE; + + set_work_data(work, (cpu << WORK_OFFQ_CPU_SHIFT) | WORK_OFFQ_CANCELING, + WORK_STRUCT_PENDING); +} + +static bool work_is_canceling(struct work_struct *work) +{ + unsigned long data = atomic_long_read(&work->data); + + return !(data & WORK_STRUCT_CWQ) && (data & WORK_OFFQ_CANCELING); +} + /* * Policy functions. These define the policies on how the global worker * pools are managed. Unless noted otherwise, these functions assume that @@ -652,10 +680,17 @@ static bool need_to_manage_workers(struct worker_pool *pool) /* Do we have too many workers and should some go away? */ static bool too_many_workers(struct worker_pool *pool) { - bool managing = mutex_is_locked(&pool->manager_mutex); + bool managing = pool->flags & POOL_MANAGING_WORKERS; int nr_idle = pool->nr_idle + managing; /* manager is considered idle */ int nr_busy = pool->nr_workers - nr_idle; + /* + * nr_idle and idle_list may disagree if idle rebinding is in + * progress. Never return %true if idle_list is empty. + */ + if (list_empty(&pool->idle_list)) + return false; + return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; } @@ -902,6 +937,206 @@ static struct worker *find_worker_executing_work(struct global_cwq *gcwq, } /** + * move_linked_works - move linked works to a list + * @work: start of series of works to be scheduled + * @head: target list to append @work to + * @nextp: out paramter for nested worklist walking + * + * Schedule linked works starting from @work to @head. Work series to + * be scheduled starts at @work and includes any consecutive work with + * WORK_STRUCT_LINKED set in its predecessor. + * + * If @nextp is not NULL, it's updated to point to the next work of + * the last scheduled work. This allows move_linked_works() to be + * nested inside outer list_for_each_entry_safe(). + * + * CONTEXT: + * spin_lock_irq(gcwq->lock). + */ +static void move_linked_works(struct work_struct *work, struct list_head *head, + struct work_struct **nextp) +{ + struct work_struct *n; + + /* + * Linked worklist will always end before the end of the list, + * use NULL for list head. + */ + list_for_each_entry_safe_from(work, n, NULL, entry) { + list_move_tail(&work->entry, head); + if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) + break; + } + + /* + * If we're already inside safe list traversal and have moved + * multiple works to the scheduled queue, the next position + * needs to be updated. + */ + if (nextp) + *nextp = n; +} + +static void cwq_activate_delayed_work(struct work_struct *work) +{ + struct cpu_workqueue_struct *cwq = get_work_cwq(work); + + trace_workqueue_activate_work(work); + move_linked_works(work, &cwq->pool->worklist, NULL); + __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work)); + cwq->nr_active++; +} + +static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq) +{ + struct work_struct *work = list_first_entry(&cwq->delayed_works, + struct work_struct, entry); + + cwq_activate_delayed_work(work); +} + +/** + * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight + * @cwq: cwq of interest + * @color: color of work which left the queue + * + * A work either has completed or is removed from pending queue, + * decrement nr_in_flight of its cwq and handle workqueue flushing. + * + * CONTEXT: + * spin_lock_irq(gcwq->lock). + */ +static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color) +{ + /* ignore uncolored works */ + if (color == WORK_NO_COLOR) + return; + + cwq->nr_in_flight[color]--; + + cwq->nr_active--; + if (!list_empty(&cwq->delayed_works)) { + /* one down, submit a delayed one */ + if (cwq->nr_active < cwq->max_active) + cwq_activate_first_delayed(cwq); + } + + /* is flush in progress and are we at the flushing tip? */ + if (likely(cwq->flush_color != color)) + return; + + /* are there still in-flight works? */ + if (cwq->nr_in_flight[color]) + return; + + /* this cwq is done, clear flush_color */ + cwq->flush_color = -1; + + /* + * If this was the last cwq, wake up the first flusher. It + * will handle the rest. + */ + if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush)) + complete(&cwq->wq->first_flusher->done); +} + +/** + * try_to_grab_pending - steal work item from worklist and disable irq + * @work: work item to steal + * @is_dwork: @work is a delayed_work + * @flags: place to store irq state + * + * Try to grab PENDING bit of @work. This function can handle @work in any + * stable state - idle, on timer or on worklist. Return values are + * + * 1 if @work was pending and we successfully stole PENDING + * 0 if @work was idle and we claimed PENDING + * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry + * -ENOENT if someone else is canceling @work, this state may persist + * for arbitrarily long + * + * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting + * interrupted while holding PENDING and @work off queue, irq must be + * disabled on entry. This, combined with delayed_work->timer being + * irqsafe, ensures that we return -EAGAIN for finite short period of time. + * + * On successful return, >= 0, irq is disabled and the caller is + * responsible for releasing it using local_irq_restore(*@flags). + * + * This function is safe to call from any context including IRQ handler. + */ +static int try_to_grab_pending(struct work_struct *work, bool is_dwork, + unsigned long *flags) +{ + struct global_cwq *gcwq; + + local_irq_save(*flags); + + /* try to steal the timer if it exists */ + if (is_dwork) { + struct delayed_work *dwork = to_delayed_work(work); + + /* + * dwork->timer is irqsafe. If del_timer() fails, it's + * guaranteed that the timer is not queued anywhere and not + * running on the local CPU. + */ + if (likely(del_timer(&dwork->timer))) + return 1; + } + + /* try to claim PENDING the normal way */ + if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) + return 0; + + /* + * The queueing is in progress, or it is already queued. Try to + * steal it from ->worklist without clearing WORK_STRUCT_PENDING. + */ + gcwq = get_work_gcwq(work); + if (!gcwq) + goto fail; + + spin_lock(&gcwq->lock); + if (!list_empty(&work->entry)) { + /* + * This work is queued, but perhaps we locked the wrong gcwq. + * In that case we must see the new value after rmb(), see + * insert_work()->wmb(). + */ + smp_rmb(); + if (gcwq == get_work_gcwq(work)) { + debug_work_deactivate(work); + + /* + * A delayed work item cannot be grabbed directly + * because it might have linked NO_COLOR work items + * which, if left on the delayed_list, will confuse + * cwq->nr_active management later on and cause + * stall. Make sure the work item is activated + * before grabbing. + */ + if (*work_data_bits(work) & WORK_STRUCT_DELAYED) + cwq_activate_delayed_work(work); + + list_del_init(&work->entry); + cwq_dec_nr_in_flight(get_work_cwq(work), + get_work_color(work)); + + spin_unlock(&gcwq->lock); + return 1; + } + } + spin_unlock(&gcwq->lock); +fail: + local_irq_restore(*flags); + if (work_is_canceling(work)) + return -ENOENT; + cpu_relax(); + return -EAGAIN; +} + +/** * insert_work - insert a work into gcwq * @cwq: cwq @work belongs to * @work: work to insert @@ -981,7 +1216,15 @@ static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, struct cpu_workqueue_struct *cwq; struct list_head *worklist; unsigned int work_flags; - unsigned long flags; + unsigned int req_cpu = cpu; + + /* + * While a work item is PENDING && off queue, a task trying to + * steal the PENDING will busy-loop waiting for it to either get + * queued or lose PENDING. Grabbing PENDING and queueing should + * happen with IRQ disabled. + */ + WARN_ON_ONCE(!irqs_disabled()); debug_work_activate(work); @@ -994,21 +1237,22 @@ static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, if (!(wq->flags & WQ_UNBOUND)) { struct global_cwq *last_gcwq; - if (unlikely(cpu == WORK_CPU_UNBOUND)) + if (cpu == WORK_CPU_UNBOUND) cpu = raw_smp_processor_id(); /* - * It's multi cpu. If @wq is non-reentrant and @work - * was previously on a different cpu, it might still - * be running there, in which case the work needs to - * be queued on that cpu to guarantee non-reentrance. + * It's multi cpu. If @work was previously on a different + * cpu, it might still be running there, in which case the + * work needs to be queued on that cpu to guarantee + * non-reentrancy. */ gcwq = get_gcwq(cpu); - if (wq->flags & WQ_NON_REENTRANT && - (last_gcwq = get_work_gcwq(work)) && last_gcwq != gcwq) { + last_gcwq = get_work_gcwq(work); + + if (last_gcwq && last_gcwq != gcwq) { struct worker *worker; - spin_lock_irqsave(&last_gcwq->lock, flags); + spin_lock(&last_gcwq->lock); worker = find_worker_executing_work(last_gcwq, work); @@ -1016,22 +1260,23 @@ static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, gcwq = last_gcwq; else { /* meh... not running there, queue here */ - spin_unlock_irqrestore(&last_gcwq->lock, flags); - spin_lock_irqsave(&gcwq->lock, flags); + spin_unlock(&last_gcwq->lock); + spin_lock(&gcwq->lock); } - } else - spin_lock_irqsave(&gcwq->lock, flags); + } else { + spin_lock(&gcwq->lock); + } } else { gcwq = get_gcwq(WORK_CPU_UNBOUND); - spin_lock_irqsave(&gcwq->lock, flags); + spin_lock(&gcwq->lock); } /* gcwq determined, get cwq and queue */ cwq = get_cwq(gcwq->cpu, wq); - trace_workqueue_queue_work(cpu, cwq, work); + trace_workqueue_queue_work(req_cpu, cwq, work); if (WARN_ON(!list_empty(&work->entry))) { - spin_unlock_irqrestore(&gcwq->lock, flags); + spin_unlock(&gcwq->lock); return; } @@ -1049,79 +1294,110 @@ static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, insert_work(cwq, work, worklist, work_flags); - spin_unlock_irqrestore(&gcwq->lock, flags); + spin_unlock(&gcwq->lock); } /** - * queue_work - queue work on a workqueue + * queue_work_on - queue work on specific cpu + * @cpu: CPU number to execute work on * @wq: workqueue to use * @work: work to queue * - * Returns 0 if @work was already on a queue, non-zero otherwise. + * Returns %false if @work was already on a queue, %true otherwise. * - * We queue the work to the CPU on which it was submitted, but if the CPU dies - * it can be processed by another CPU. + * We queue the work to a specific CPU, the caller must ensure it + * can't go away. */ -int queue_work(struct workqueue_struct *wq, struct work_struct *work) +bool queue_work_on(int cpu, struct workqueue_struct *wq, + struct work_struct *work) { - int ret; + bool ret = false; + unsigned long flags; - ret = queue_work_on(get_cpu(), wq, work); - put_cpu(); + local_irq_save(flags); + + if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { + __queue_work(cpu, wq, work); + ret = true; + } + local_irq_restore(flags); return ret; } -EXPORT_SYMBOL_GPL(queue_work); +EXPORT_SYMBOL_GPL(queue_work_on); /** - * queue_work_on - queue work on specific cpu - * @cpu: CPU number to execute work on + * queue_work - queue work on a workqueue * @wq: workqueue to use * @work: work to queue * - * Returns 0 if @work was already on a queue, non-zero otherwise. + * Returns %false if @work was already on a queue, %true otherwise. * - * We queue the work to a specific CPU, the caller must ensure it - * can't go away. + * We queue the work to the CPU on which it was submitted, but if the CPU dies + * it can be processed by another CPU. */ -int -queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work) +bool queue_work(struct workqueue_struct *wq, struct work_struct *work) { - int ret = 0; - - if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { - __queue_work(cpu, wq, work); - ret = 1; - } - return ret; + return queue_work_on(WORK_CPU_UNBOUND, wq, work); } -EXPORT_SYMBOL_GPL(queue_work_on); +EXPORT_SYMBOL_GPL(queue_work); -static 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 cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work); - __queue_work(smp_processor_id(), cwq->wq, &dwork->work); + /* should have been called from irqsafe timer with irq already off */ + __queue_work(dwork->cpu, cwq->wq, &dwork->work); } +EXPORT_SYMBOL_GPL(delayed_work_timer_fn); -/** - * queue_delayed_work - queue work on a workqueue after delay - * @wq: workqueue to use - * @dwork: delayable work to queue - * @delay: number of jiffies to wait before queueing - * - * Returns 0 if @work was already on a queue, non-zero otherwise. - */ -int queue_delayed_work(struct workqueue_struct *wq, - struct delayed_work *dwork, unsigned long delay) +static void __queue_delayed_work(int cpu, struct workqueue_struct *wq, + struct delayed_work *dwork, unsigned long delay) { - if (delay == 0) - return queue_work(wq, &dwork->work); + struct timer_list *timer = &dwork->timer; + struct work_struct *work = &dwork->work; + unsigned int lcpu; + + WARN_ON_ONCE(timer->function != delayed_work_timer_fn || + timer->data != (unsigned long)dwork); + BUG_ON(timer_pending(timer)); + BUG_ON(!list_empty(&work->entry)); - return queue_delayed_work_on(-1, wq, dwork, delay); + timer_stats_timer_set_start_info(&dwork->timer); + + /* + * This stores cwq for the moment, for the timer_fn. Note that the + * work's gcwq is preserved to allow reentrance detection for + * delayed works. + */ + if (!(wq->flags & WQ_UNBOUND)) { + struct global_cwq *gcwq = get_work_gcwq(work); + + /* + * If we cannot get the last gcwq from @work directly, + * select the last CPU such that it avoids unnecessarily + * triggering non-reentrancy check in __queue_work(). + */ + lcpu = cpu; + if (gcwq) + lcpu = gcwq->cpu; + if (lcpu == WORK_CPU_UNBOUND) + lcpu = raw_smp_processor_id(); + } else { + lcpu = WORK_CPU_UNBOUND; + } + + set_work_cwq(work, get_cwq(lcpu, wq), 0); + + dwork->cpu = cpu; + timer->expires = jiffies + delay; + + if (unlikely(cpu != WORK_CPU_UNBOUND)) + add_timer_on(timer, cpu); + else + add_timer(timer); } -EXPORT_SYMBOL_GPL(queue_delayed_work); /** * queue_delayed_work_on - queue work on specific CPU after delay @@ -1130,53 +1406,100 @@ EXPORT_SYMBOL_GPL(queue_delayed_work); * @dwork: work to queue * @delay: number of jiffies to wait before queueing * - * Returns 0 if @work was already on a queue, non-zero otherwise. + * Returns %false if @work was already on a queue, %true otherwise. If + * @delay is zero and @dwork is idle, it will be scheduled for immediate + * execution. */ -int queue_delayed_work_on(int cpu, struct workqueue_struct *wq, - struct delayed_work *dwork, unsigned long delay) +bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq, + struct delayed_work *dwork, unsigned long delay) { - int ret = 0; - struct timer_list *timer = &dwork->timer; struct work_struct *work = &dwork->work; + bool ret = false; + unsigned long flags; - if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { - unsigned int lcpu; + if (!delay) + return queue_work_on(cpu, wq, &dwork->work); - BUG_ON(timer_pending(timer)); - BUG_ON(!list_empty(&work->entry)); + /* read the comment in __queue_work() */ + local_irq_save(flags); - timer_stats_timer_set_start_info(&dwork->timer); + if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { + __queue_delayed_work(cpu, wq, dwork, delay); + ret = true; + } - /* - * This stores cwq for the moment, for the timer_fn. - * Note that the work's gcwq is preserved to allow - * reentrance detection for delayed works. - */ - if (!(wq->flags & WQ_UNBOUND)) { - struct global_cwq *gcwq = get_work_gcwq(work); + local_irq_restore(flags); + return ret; +} +EXPORT_SYMBOL_GPL(queue_delayed_work_on); - if (gcwq && gcwq->cpu != WORK_CPU_UNBOUND) - lcpu = gcwq->cpu; - else - lcpu = raw_smp_processor_id(); - } else - lcpu = WORK_CPU_UNBOUND; +/** + * queue_delayed_work - queue work on a workqueue after delay + * @wq: workqueue to use + * @dwork: delayable work to queue + * @delay: number of jiffies to wait before queueing + * + * Equivalent to queue_delayed_work_on() but tries to use the local CPU. + */ +bool queue_delayed_work(struct workqueue_struct *wq, + struct delayed_work *dwork, unsigned long delay) +{ + return queue_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay); +} +EXPORT_SYMBOL_GPL(queue_delayed_work); - set_work_cwq(work, get_cwq(lcpu, wq), 0); +/** + * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU + * @cpu: CPU number to execute work on + * @wq: workqueue to use + * @dwork: work to queue + * @delay: number of jiffies to wait before queueing + * + * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise, + * modify @dwork's timer so that it expires after @delay. If @delay is + * zero, @work is guaranteed to be scheduled immediately regardless of its + * current state. + * + * Returns %false if @dwork was idle and queued, %true if @dwork was + * pending and its timer was modified. + * + * This function is safe to call from any context including IRQ handler. + * See try_to_grab_pending() for details. + */ +bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq, + struct delayed_work *dwork, unsigned long delay) +{ + unsigned long flags; + int ret; - timer->expires = jiffies + delay; - timer->data = (unsigned long)dwork; - timer->function = delayed_work_timer_fn; + do { + ret = try_to_grab_pending(&dwork->work, true, &flags); + } while (unlikely(ret == -EAGAIN)); - if (unlikely(cpu >= 0)) - add_timer_on(timer, cpu); - else - add_timer(timer); - ret = 1; + if (likely(ret >= 0)) { + __queue_delayed_work(cpu, wq, dwork, delay); + local_irq_restore(flags); } + + /* -ENOENT from try_to_grab_pending() becomes %true */ return ret; } -EXPORT_SYMBOL_GPL(queue_delayed_work_on); +EXPORT_SYMBOL_GPL(mod_delayed_work_on); + +/** + * mod_delayed_work - modify delay of or queue a delayed work + * @wq: workqueue to use + * @dwork: work to queue + * @delay: number of jiffies to wait before queueing + * + * mod_delayed_work_on() on local CPU. + */ +bool mod_delayed_work(struct workqueue_struct *wq, struct delayed_work *dwork, + unsigned long delay) +{ + return mod_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay); +} +EXPORT_SYMBOL_GPL(mod_delayed_work); /** * worker_enter_idle - enter idle state @@ -1304,28 +1627,21 @@ __acquires(&gcwq->lock) } } -struct idle_rebind { - int cnt; /* # workers to be rebound */ - struct completion done; /* all workers rebound */ -}; - /* - * Rebind an idle @worker to its CPU. During CPU onlining, this has to - * happen synchronously for idle workers. worker_thread() will test - * %WORKER_REBIND before leaving idle and call this function. + * Rebind an idle @worker to its CPU. worker_thread() will test + * list_empty(@worker->entry) before leaving idle and call this function. */ static void idle_worker_rebind(struct worker *worker) { struct global_cwq *gcwq = worker->pool->gcwq; - /* CPU must be online at this point */ - WARN_ON(!worker_maybe_bind_and_lock(worker)); - if (!--worker->idle_rebind->cnt) - complete(&worker->idle_rebind->done); - spin_unlock_irq(&worker->pool->gcwq->lock); + /* CPU may go down again inbetween, clear UNBOUND only on success */ + if (worker_maybe_bind_and_lock(worker)) + worker_clr_flags(worker, WORKER_UNBOUND); - /* we did our part, wait for rebind_workers() to finish up */ - wait_event(gcwq->rebind_hold, !(worker->flags & WORKER_REBIND)); + /* rebind complete, become available again */ + list_add(&worker->entry, &worker->pool->idle_list); + spin_unlock_irq(&gcwq->lock); } /* @@ -1340,7 +1656,7 @@ static void busy_worker_rebind_fn(struct work_struct *work) struct global_cwq *gcwq = worker->pool->gcwq; if (worker_maybe_bind_and_lock(worker)) - worker_clr_flags(worker, WORKER_REBIND); + worker_clr_flags(worker, WORKER_UNBOUND); spin_unlock_irq(&gcwq->lock); } @@ -1352,102 +1668,74 @@ static void busy_worker_rebind_fn(struct work_struct *work) * @gcwq->cpu is coming online. Rebind all workers to the CPU. Rebinding * is different for idle and busy ones. * - * The idle ones should be rebound synchronously and idle rebinding should - * be complete before any worker starts executing work items with - * concurrency management enabled; otherwise, scheduler may oops trying to - * wake up non-local idle worker from wq_worker_sleeping(). + * Idle ones will be removed from the idle_list and woken up. They will + * add themselves back after completing rebind. This ensures that the + * idle_list doesn't contain any unbound workers when re-bound busy workers + * try to perform local wake-ups for concurrency management. * - * This is achieved by repeatedly requesting rebinding until all idle - * workers are known to have been rebound under @gcwq->lock and holding all - * idle workers from becoming busy until idle rebinding is complete. + * Busy workers can rebind after they finish their current work items. + * Queueing the rebind work item at the head of the scheduled list is + * enough. Note that nr_running will be properly bumped as busy workers + * rebind. * - * Once idle workers are rebound, busy workers can be rebound as they - * finish executing their current work items. Queueing the rebind work at - * the head of their scheduled lists is enough. Note that nr_running will - * be properbly bumped as busy workers rebind. - * - * On return, all workers are guaranteed to either be bound or have rebind - * work item scheduled. + * On return, all non-manager workers are scheduled for rebind - see + * manage_workers() for the manager special case. Any idle worker + * including the manager will not appear on @idle_list until rebind is + * complete, making local wake-ups safe. */ static void rebind_workers(struct global_cwq *gcwq) - __releases(&gcwq->lock) __acquires(&gcwq->lock) { - struct idle_rebind idle_rebind; struct worker_pool *pool; - struct worker *worker; + struct worker *worker, *n; struct hlist_node *pos; int i; lockdep_assert_held(&gcwq->lock); for_each_worker_pool(pool, gcwq) - lockdep_assert_held(&pool->manager_mutex); + lockdep_assert_held(&pool->assoc_mutex); - /* - * Rebind idle workers. Interlocked both ways. We wait for - * workers to rebind via @idle_rebind.done. Workers will wait for - * us to finish up by watching %WORKER_REBIND. - */ - init_completion(&idle_rebind.done); -retry: - idle_rebind.cnt = 1; - INIT_COMPLETION(idle_rebind.done); - - /* set REBIND and kick idle ones, we'll wait for these later */ + /* dequeue and kick idle ones */ for_each_worker_pool(pool, gcwq) { - list_for_each_entry(worker, &pool->idle_list, entry) { - if (worker->flags & WORKER_REBIND) - continue; - - /* morph UNBOUND to REBIND */ - worker->flags &= ~WORKER_UNBOUND; - worker->flags |= WORKER_REBIND; - - idle_rebind.cnt++; - worker->idle_rebind = &idle_rebind; + list_for_each_entry_safe(worker, n, &pool->idle_list, entry) { + /* + * idle workers should be off @pool->idle_list + * until rebind is complete to avoid receiving + * premature local wake-ups. + */ + list_del_init(&worker->entry); - /* worker_thread() will call idle_worker_rebind() */ + /* + * worker_thread() will see the above dequeuing + * and call idle_worker_rebind(). + */ wake_up_process(worker->task); } } - if (--idle_rebind.cnt) { - spin_unlock_irq(&gcwq->lock); - wait_for_completion(&idle_rebind.done); - spin_lock_irq(&gcwq->lock); - /* busy ones might have become idle while waiting, retry */ - goto retry; - } - - /* - * All idle workers are rebound and waiting for %WORKER_REBIND to - * be cleared inside idle_worker_rebind(). Clear and release. - * Clearing %WORKER_REBIND from this foreign context is safe - * because these workers are still guaranteed to be idle. - */ - for_each_worker_pool(pool, gcwq) - list_for_each_entry(worker, &pool->idle_list, entry) - worker->flags &= ~WORKER_REBIND; - - wake_up_all(&gcwq->rebind_hold); - /* rebind busy workers */ for_each_busy_worker(worker, i, pos, gcwq) { struct work_struct *rebind_work = &worker->rebind_work; - - /* morph UNBOUND to REBIND */ - worker->flags &= ~WORKER_UNBOUND; - worker->flags |= WORKER_REBIND; + struct workqueue_struct *wq; if (test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(rebind_work))) continue; - /* wq doesn't matter, use the default one */ debug_work_activate(rebind_work); - insert_work(get_cwq(gcwq->cpu, system_wq), rebind_work, - worker->scheduled.next, - work_color_to_flags(WORK_NO_COLOR)); + + /* + * wq doesn't really matter but let's keep @worker->pool + * and @cwq->pool consistent for sanity. + */ + if (worker_pool_pri(worker->pool)) + wq = system_highpri_wq; + else + wq = system_wq; + + insert_work(get_cwq(gcwq->cpu, wq), rebind_work, + worker->scheduled.next, + work_color_to_flags(WORK_NO_COLOR)); } } @@ -1794,9 +2082,45 @@ static bool manage_workers(struct worker *worker) struct worker_pool *pool = worker->pool; bool ret = false; - if (!mutex_trylock(&pool->manager_mutex)) + if (pool->flags & POOL_MANAGING_WORKERS) return ret; + pool->flags |= POOL_MANAGING_WORKERS; + + /* + * To simplify both worker management and CPU hotplug, hold off + * management while hotplug is in progress. CPU hotplug path can't + * grab %POOL_MANAGING_WORKERS to achieve this because that can + * lead to idle worker depletion (all become busy thinking someone + * else is managing) which in turn can result in deadlock under + * extreme circumstances. Use @pool->assoc_mutex to synchronize + * manager against CPU hotplug. + * + * assoc_mutex would always be free unless CPU hotplug is in + * progress. trylock first without dropping @gcwq->lock. + */ + if (unlikely(!mutex_trylock(&pool->assoc_mutex))) { + spin_unlock_irq(&pool->gcwq->lock); + mutex_lock(&pool->assoc_mutex); + /* + * CPU hotplug could have happened while we were waiting + * for assoc_mutex. Hotplug itself can't handle us + * because manager isn't either on idle or busy list, and + * @gcwq's state and ours could have deviated. + * + * As hotplug is now excluded via assoc_mutex, we can + * simply try to bind. It will succeed or fail depending + * on @gcwq's current state. Try it and adjust + * %WORKER_UNBOUND accordingly. + */ + if (worker_maybe_bind_and_lock(worker)) + worker->flags &= ~WORKER_UNBOUND; + else + worker->flags |= WORKER_UNBOUND; + + ret = true; + } + pool->flags &= ~POOL_MANAGE_WORKERS; /* @@ -1806,112 +2130,12 @@ static bool manage_workers(struct worker *worker) ret |= maybe_destroy_workers(pool); ret |= maybe_create_worker(pool); - mutex_unlock(&pool->manager_mutex); + pool->flags &= ~POOL_MANAGING_WORKERS; + mutex_unlock(&pool->assoc_mutex); return ret; } /** - * move_linked_works - move linked works to a list - * @work: start of series of works to be scheduled - * @head: target list to append @work to - * @nextp: out paramter for nested worklist walking - * - * Schedule linked works starting from @work to @head. Work series to - * be scheduled starts at @work and includes any consecutive work with - * WORK_STRUCT_LINKED set in its predecessor. - * - * If @nextp is not NULL, it's updated to point to the next work of - * the last scheduled work. This allows move_linked_works() to be - * nested inside outer list_for_each_entry_safe(). - * - * CONTEXT: - * spin_lock_irq(gcwq->lock). - */ -static void move_linked_works(struct work_struct *work, struct list_head *head, - struct work_struct **nextp) -{ - struct work_struct *n; - - /* - * Linked worklist will always end before the end of the list, - * use NULL for list head. - */ - list_for_each_entry_safe_from(work, n, NULL, entry) { - list_move_tail(&work->entry, head); - if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) - break; - } - - /* - * If we're already inside safe list traversal and have moved - * multiple works to the scheduled queue, the next position - * needs to be updated. - */ - if (nextp) - *nextp = n; -} - -static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq) -{ - struct work_struct *work = list_first_entry(&cwq->delayed_works, - struct work_struct, entry); - - trace_workqueue_activate_work(work); - move_linked_works(work, &cwq->pool->worklist, NULL); - __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work)); - cwq->nr_active++; -} - -/** - * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight - * @cwq: cwq of interest - * @color: color of work which left the queue - * @delayed: for a delayed work - * - * A work either has completed or is removed from pending queue, - * decrement nr_in_flight of its cwq and handle workqueue flushing. - * - * CONTEXT: - * spin_lock_irq(gcwq->lock). - */ -static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color, - bool delayed) -{ - /* ignore uncolored works */ - if (color == WORK_NO_COLOR) - return; - - cwq->nr_in_flight[color]--; - - if (!delayed) { - cwq->nr_active--; - if (!list_empty(&cwq->delayed_works)) { - /* one down, submit a delayed one */ - if (cwq->nr_active < cwq->max_active) - cwq_activate_first_delayed(cwq); - } - } - - /* is flush in progress and are we at the flushing tip? */ - if (likely(cwq->flush_color != color)) - return; - - /* are there still in-flight works? */ - if (cwq->nr_in_flight[color]) - return; - - /* this cwq is done, clear flush_color */ - cwq->flush_color = -1; - - /* - * If this was the last cwq, wake up the first flusher. It - * will handle the rest. - */ - if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush)) - complete(&cwq->wq->first_flusher->done); -} - -/** * process_one_work - process single work * @worker: self * @work: work to process @@ -1954,7 +2178,7 @@ __acquires(&gcwq->lock) * necessary to avoid spurious warnings from rescuers servicing the * unbound or a disassociated gcwq. */ - WARN_ON_ONCE(!(worker->flags & (WORKER_UNBOUND | WORKER_REBIND)) && + WARN_ON_ONCE(!(worker->flags & WORKER_UNBOUND) && !(gcwq->flags & GCWQ_DISASSOCIATED) && raw_smp_processor_id() != gcwq->cpu); @@ -1970,15 +2194,13 @@ __acquires(&gcwq->lock) return; } - /* claim and process */ + /* claim and dequeue */ debug_work_deactivate(work); hlist_add_head(&worker->hentry, bwh); worker->current_work = work; worker->current_cwq = cwq; work_color = get_work_color(work); - /* record the current cpu number in the work data and dequeue */ - set_work_cpu(work, gcwq->cpu); list_del_init(&work->entry); /* @@ -1995,9 +2217,16 @@ __acquires(&gcwq->lock) if ((worker->flags & WORKER_UNBOUND) && need_more_worker(pool)) wake_up_worker(pool); + /* + * Record the last CPU and clear PENDING which should be the last + * update to @work. Also, do this inside @gcwq->lock so that + * PENDING and queued state changes happen together while IRQ is + * disabled. + */ + set_work_cpu_and_clear_pending(work, gcwq->cpu); + spin_unlock_irq(&gcwq->lock); - work_clear_pending(work); lock_map_acquire_read(&cwq->wq->lockdep_map); lock_map_acquire(&lockdep_map); trace_workqueue_execute_start(work); @@ -2011,11 +2240,9 @@ __acquires(&gcwq->lock) lock_map_release(&cwq->wq->lockdep_map); if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { - printk(KERN_ERR "BUG: workqueue leaked lock or atomic: " - "%s/0x%08x/%d\n", - current->comm, preempt_count(), task_pid_nr(current)); - printk(KERN_ERR " last function: "); - print_symbol("%s\n", (unsigned long)f); + pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n" + " last function: %pf\n", + current->comm, preempt_count(), task_pid_nr(current), f); debug_show_held_locks(current); dump_stack(); } @@ -2030,7 +2257,7 @@ __acquires(&gcwq->lock) hlist_del_init(&worker->hentry); worker->current_work = NULL; worker->current_cwq = NULL; - cwq_dec_nr_in_flight(cwq, work_color, false); + cwq_dec_nr_in_flight(cwq, work_color); } /** @@ -2075,18 +2302,17 @@ static int worker_thread(void *__worker) woke_up: spin_lock_irq(&gcwq->lock); - /* - * DIE can be set only while idle and REBIND set while busy has - * @worker->rebind_work scheduled. Checking here is enough. - */ - if (unlikely(worker->flags & (WORKER_REBIND | WORKER_DIE))) { + /* we are off idle list if destruction or rebind is requested */ + if (unlikely(list_empty(&worker->entry))) { spin_unlock_irq(&gcwq->lock); + /* if DIE is set, destruction is requested */ if (worker->flags & WORKER_DIE) { worker->task->flags &= ~PF_WQ_WORKER; return 0; } + /* otherwise, rebind */ idle_worker_rebind(worker); goto woke_up; } @@ -2569,8 +2795,8 @@ reflush: 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); + pr_warn("workqueue %s: flush on destruction isn't complete after %u tries\n", + wq->name, flush_cnt); goto reflush; } @@ -2581,8 +2807,7 @@ reflush: } EXPORT_SYMBOL_GPL(drain_workqueue); -static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr, - bool wait_executing) +static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr) { struct worker *worker = NULL; struct global_cwq *gcwq; @@ -2604,13 +2829,12 @@ static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr, cwq = get_work_cwq(work); if (unlikely(!cwq || gcwq != cwq->pool->gcwq)) goto already_gone; - } else if (wait_executing) { + } else { worker = find_worker_executing_work(gcwq, work); if (!worker) goto already_gone; cwq = worker->current_cwq; - } else - goto already_gone; + } insert_wq_barrier(cwq, barr, work, worker); spin_unlock_irq(&gcwq->lock); @@ -2637,15 +2861,8 @@ already_gone: * flush_work - wait for a work to finish executing the last queueing instance * @work: the work to flush * - * Wait until @work has finished execution. This function considers - * only the last queueing instance of @work. If @work has been - * enqueued across different CPUs on a non-reentrant workqueue or on - * multiple workqueues, @work might still be executing on return on - * some of the CPUs from earlier queueing. - * - * If @work was queued only on a non-reentrant, ordered or unbound - * workqueue, @work is guaranteed to be idle on return if it hasn't - * been requeued since flush started. + * Wait until @work has finished execution. @work is guaranteed to be idle + * on return if it hasn't been requeued since flush started. * * RETURNS: * %true if flush_work() waited for the work to finish execution, @@ -2658,140 +2875,36 @@ bool flush_work(struct work_struct *work) lock_map_acquire(&work->lockdep_map); lock_map_release(&work->lockdep_map); - if (start_flush_work(work, &barr, true)) { + if (start_flush_work(work, &barr)) { wait_for_completion(&barr.done); destroy_work_on_stack(&barr.work); return true; - } else - return false; -} -EXPORT_SYMBOL_GPL(flush_work); - -static bool wait_on_cpu_work(struct global_cwq *gcwq, struct work_struct *work) -{ - struct wq_barrier barr; - struct worker *worker; - - spin_lock_irq(&gcwq->lock); - - worker = find_worker_executing_work(gcwq, work); - if (unlikely(worker)) - insert_wq_barrier(worker->current_cwq, &barr, work, worker); - - spin_unlock_irq(&gcwq->lock); - - if (unlikely(worker)) { - wait_for_completion(&barr.done); - destroy_work_on_stack(&barr.work); - return true; - } else + } else { return false; -} - -static bool wait_on_work(struct work_struct *work) -{ - bool ret = false; - int cpu; - - might_sleep(); - - lock_map_acquire(&work->lockdep_map); - lock_map_release(&work->lockdep_map); - - for_each_gcwq_cpu(cpu) - ret |= wait_on_cpu_work(get_gcwq(cpu), work); - return ret; -} - -/** - * flush_work_sync - wait until a work has finished execution - * @work: the work to flush - * - * Wait until @work has finished execution. On return, it's - * guaranteed that all queueing instances of @work which happened - * before this function is called are finished. In other words, if - * @work hasn't been requeued since this function was called, @work is - * guaranteed to be idle on return. - * - * RETURNS: - * %true if flush_work_sync() waited for the work to finish execution, - * %false if it was already idle. - */ -bool flush_work_sync(struct work_struct *work) -{ - struct wq_barrier barr; - bool pending, waited; - - /* we'll wait for executions separately, queue barr only if pending */ - pending = start_flush_work(work, &barr, false); - - /* wait for executions to finish */ - waited = wait_on_work(work); - - /* wait for the pending one */ - if (pending) { - wait_for_completion(&barr.done); - destroy_work_on_stack(&barr.work); - } - - return pending || waited; -} -EXPORT_SYMBOL_GPL(flush_work_sync); - -/* - * Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit, - * so this work can't be re-armed in any way. - */ -static int try_to_grab_pending(struct work_struct *work) -{ - struct global_cwq *gcwq; - int ret = -1; - - if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) - return 0; - - /* - * The queueing is in progress, or it is already queued. Try to - * steal it from ->worklist without clearing WORK_STRUCT_PENDING. - */ - gcwq = get_work_gcwq(work); - if (!gcwq) - return ret; - - spin_lock_irq(&gcwq->lock); - if (!list_empty(&work->entry)) { - /* - * This work is queued, but perhaps we locked the wrong gcwq. - * In that case we must see the new value after rmb(), see - * insert_work()->wmb(). - */ - smp_rmb(); - if (gcwq == get_work_gcwq(work)) { - debug_work_deactivate(work); - list_del_init(&work->entry); - cwq_dec_nr_in_flight(get_work_cwq(work), - get_work_color(work), - *work_data_bits(work) & WORK_STRUCT_DELAYED); - ret = 1; - } } - spin_unlock_irq(&gcwq->lock); - - return ret; } +EXPORT_SYMBOL_GPL(flush_work); -static bool __cancel_work_timer(struct work_struct *work, - struct timer_list* timer) +static bool __cancel_work_timer(struct work_struct *work, bool is_dwork) { + unsigned long flags; int ret; do { - ret = (timer && likely(del_timer(timer))); - if (!ret) - ret = try_to_grab_pending(work); - wait_on_work(work); + ret = try_to_grab_pending(work, is_dwork, &flags); + /* + * If someone else is canceling, wait for the same event it + * would be waiting for before retrying. + */ + if (unlikely(ret == -ENOENT)) + flush_work(work); } while (unlikely(ret < 0)); + /* tell other tasks trying to grab @work to back off */ + mark_work_canceling(work); + local_irq_restore(flags); + + flush_work(work); clear_work_data(work); return ret; } @@ -2816,7 +2929,7 @@ static bool __cancel_work_timer(struct work_struct *work, */ bool cancel_work_sync(struct work_struct *work) { - return __cancel_work_timer(work, NULL); + return __cancel_work_timer(work, false); } EXPORT_SYMBOL_GPL(cancel_work_sync); @@ -2834,33 +2947,44 @@ EXPORT_SYMBOL_GPL(cancel_work_sync); */ bool flush_delayed_work(struct delayed_work *dwork) { + local_irq_disable(); if (del_timer_sync(&dwork->timer)) - __queue_work(raw_smp_processor_id(), + __queue_work(dwork->cpu, get_work_cwq(&dwork->work)->wq, &dwork->work); + local_irq_enable(); return flush_work(&dwork->work); } EXPORT_SYMBOL(flush_delayed_work); /** - * flush_delayed_work_sync - wait for a dwork to finish - * @dwork: the delayed work to flush + * cancel_delayed_work - cancel a delayed work + * @dwork: delayed_work to cancel * - * Delayed timer is cancelled and the pending work is queued for - * execution immediately. Other than timer handling, its behavior - * is identical to flush_work_sync(). + * Kill off a pending delayed_work. Returns %true if @dwork was pending + * and canceled; %false if wasn't pending. Note that the work callback + * function may still be running on return, unless it returns %true and the + * work doesn't re-arm itself. Explicitly flush or use + * cancel_delayed_work_sync() to wait on it. * - * RETURNS: - * %true if flush_work_sync() waited for the work to finish execution, - * %false if it was already idle. + * This function is safe to call from any context including IRQ handler. */ -bool flush_delayed_work_sync(struct delayed_work *dwork) +bool cancel_delayed_work(struct delayed_work *dwork) { - if (del_timer_sync(&dwork->timer)) - __queue_work(raw_smp_processor_id(), - get_work_cwq(&dwork->work)->wq, &dwork->work); - return flush_work_sync(&dwork->work); + unsigned long flags; + int ret; + + do { + ret = try_to_grab_pending(&dwork->work, true, &flags); + } while (unlikely(ret == -EAGAIN)); + + if (unlikely(ret < 0)) + return false; + + set_work_cpu_and_clear_pending(&dwork->work, work_cpu(&dwork->work)); + local_irq_restore(flags); + return true; } -EXPORT_SYMBOL(flush_delayed_work_sync); +EXPORT_SYMBOL(cancel_delayed_work); /** * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish @@ -2873,54 +2997,39 @@ EXPORT_SYMBOL(flush_delayed_work_sync); */ bool cancel_delayed_work_sync(struct delayed_work *dwork) { - return __cancel_work_timer(&dwork->work, &dwork->timer); + return __cancel_work_timer(&dwork->work, true); } EXPORT_SYMBOL(cancel_delayed_work_sync); /** - * schedule_work - put work task in global workqueue - * @work: job to be done - * - * Returns zero if @work was already on the kernel-global workqueue and - * non-zero otherwise. - * - * This puts a job in the kernel-global workqueue if it was not already - * queued and leaves it in the same position on the kernel-global - * workqueue otherwise. - */ -int schedule_work(struct work_struct *work) -{ - return queue_work(system_wq, work); -} -EXPORT_SYMBOL(schedule_work); - -/* * schedule_work_on - put work task on a specific cpu * @cpu: cpu to put the work task on * @work: job to be done * * This puts a job on a specific cpu */ -int schedule_work_on(int cpu, struct work_struct *work) +bool schedule_work_on(int cpu, struct work_struct *work) { return queue_work_on(cpu, system_wq, work); } EXPORT_SYMBOL(schedule_work_on); /** - * schedule_delayed_work - put work task in global workqueue after delay - * @dwork: job to be done - * @delay: number of jiffies to wait or 0 for immediate execution + * schedule_work - put work task in global workqueue + * @work: job to be done * - * After waiting for a given time this puts a job in the kernel-global - * workqueue. + * Returns %false if @work was already on the kernel-global workqueue and + * %true otherwise. + * + * This puts a job in the kernel-global workqueue if it was not already + * queued and leaves it in the same position on the kernel-global + * workqueue otherwise. */ -int schedule_delayed_work(struct delayed_work *dwork, - unsigned long delay) +bool schedule_work(struct work_struct *work) { - return queue_delayed_work(system_wq, dwork, delay); + return queue_work(system_wq, work); } -EXPORT_SYMBOL(schedule_delayed_work); +EXPORT_SYMBOL(schedule_work); /** * schedule_delayed_work_on - queue work in global workqueue on CPU after delay @@ -2931,14 +3040,28 @@ EXPORT_SYMBOL(schedule_delayed_work); * After waiting for a given time this puts a job in the kernel-global * workqueue on the specified CPU. */ -int schedule_delayed_work_on(int cpu, - struct delayed_work *dwork, unsigned long delay) +bool schedule_delayed_work_on(int cpu, struct delayed_work *dwork, + unsigned long delay) { return queue_delayed_work_on(cpu, system_wq, dwork, delay); } EXPORT_SYMBOL(schedule_delayed_work_on); /** + * schedule_delayed_work - put work task in global workqueue after delay + * @dwork: job to be done + * @delay: number of jiffies to wait or 0 for immediate execution + * + * After waiting for a given time this puts a job in the kernel-global + * workqueue. + */ +bool schedule_delayed_work(struct delayed_work *dwork, unsigned long delay) +{ + return queue_delayed_work(system_wq, dwork, delay); +} +EXPORT_SYMBOL(schedule_delayed_work); + +/** * schedule_on_each_cpu - execute a function synchronously on each online CPU * @func: the function to call * @@ -3085,9 +3208,8 @@ static int wq_clamp_max_active(int max_active, unsigned int flags, int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; if (max_active < 1 || max_active > lim) - printk(KERN_WARNING "workqueue: max_active %d requested for %s " - "is out of range, clamping between %d and %d\n", - max_active, name, 1, lim); + pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n", + max_active, name, 1, lim); return clamp_val(max_active, 1, lim); } @@ -3243,6 +3365,26 @@ void destroy_workqueue(struct workqueue_struct *wq) EXPORT_SYMBOL_GPL(destroy_workqueue); /** + * cwq_set_max_active - adjust max_active of a cwq + * @cwq: target cpu_workqueue_struct + * @max_active: new max_active value. + * + * Set @cwq->max_active to @max_active and activate delayed works if + * increased. + * + * CONTEXT: + * spin_lock_irq(gcwq->lock). + */ +static void cwq_set_max_active(struct cpu_workqueue_struct *cwq, int max_active) +{ + cwq->max_active = max_active; + + while (!list_empty(&cwq->delayed_works) && + cwq->nr_active < cwq->max_active) + cwq_activate_first_delayed(cwq); +} + +/** * workqueue_set_max_active - adjust max_active of a workqueue * @wq: target workqueue * @max_active: new max_active value. @@ -3269,7 +3411,7 @@ void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) if (!(wq->flags & WQ_FREEZABLE) || !(gcwq->flags & GCWQ_FREEZING)) - get_cwq(gcwq->cpu, wq)->max_active = max_active; + cwq_set_max_active(get_cwq(gcwq->cpu, wq), max_active); spin_unlock_irq(&gcwq->lock); } @@ -3364,23 +3506,23 @@ EXPORT_SYMBOL_GPL(work_busy); */ /* claim manager positions of all pools */ -static void gcwq_claim_management_and_lock(struct global_cwq *gcwq) +static void gcwq_claim_assoc_and_lock(struct global_cwq *gcwq) { struct worker_pool *pool; for_each_worker_pool(pool, gcwq) - mutex_lock_nested(&pool->manager_mutex, pool - gcwq->pools); + mutex_lock_nested(&pool->assoc_mutex, pool - gcwq->pools); spin_lock_irq(&gcwq->lock); } /* release manager positions */ -static void gcwq_release_management_and_unlock(struct global_cwq *gcwq) +static void gcwq_release_assoc_and_unlock(struct global_cwq *gcwq) { struct worker_pool *pool; spin_unlock_irq(&gcwq->lock); for_each_worker_pool(pool, gcwq) - mutex_unlock(&pool->manager_mutex); + mutex_unlock(&pool->assoc_mutex); } static void gcwq_unbind_fn(struct work_struct *work) @@ -3393,7 +3535,7 @@ static void gcwq_unbind_fn(struct work_struct *work) BUG_ON(gcwq->cpu != smp_processor_id()); - gcwq_claim_management_and_lock(gcwq); + gcwq_claim_assoc_and_lock(gcwq); /* * We've claimed all manager positions. Make all workers unbound @@ -3410,7 +3552,7 @@ static void gcwq_unbind_fn(struct work_struct *work) gcwq->flags |= GCWQ_DISASSOCIATED; - gcwq_release_management_and_unlock(gcwq); + gcwq_release_assoc_and_unlock(gcwq); /* * Call schedule() so that we cross rq->lock and thus can guarantee @@ -3438,7 +3580,7 @@ static void gcwq_unbind_fn(struct work_struct *work) * Workqueues should be brought up before normal priority CPU notifiers. * This will be registered high priority CPU notifier. */ -static int __devinit workqueue_cpu_up_callback(struct notifier_block *nfb, +static int __cpuinit workqueue_cpu_up_callback(struct notifier_block *nfb, unsigned long action, void *hcpu) { @@ -3466,10 +3608,10 @@ static int __devinit workqueue_cpu_up_callback(struct notifier_block *nfb, case CPU_DOWN_FAILED: case CPU_ONLINE: - gcwq_claim_management_and_lock(gcwq); + gcwq_claim_assoc_and_lock(gcwq); gcwq->flags &= ~GCWQ_DISASSOCIATED; rebind_workers(gcwq); - gcwq_release_management_and_unlock(gcwq); + gcwq_release_assoc_and_unlock(gcwq); break; } return NOTIFY_OK; @@ -3479,7 +3621,7 @@ static int __devinit workqueue_cpu_up_callback(struct notifier_block *nfb, * Workqueues should be brought down after normal priority CPU notifiers. * This will be registered as low priority CPU notifier. */ -static int __devinit workqueue_cpu_down_callback(struct notifier_block *nfb, +static int __cpuinit workqueue_cpu_down_callback(struct notifier_block *nfb, unsigned long action, void *hcpu) { @@ -3490,7 +3632,7 @@ static int __devinit workqueue_cpu_down_callback(struct notifier_block *nfb, case CPU_DOWN_PREPARE: /* unbinding should happen on the local CPU */ INIT_WORK_ONSTACK(&unbind_work, gcwq_unbind_fn); - schedule_work_on(cpu, &unbind_work); + queue_work_on(cpu, system_highpri_wq, &unbind_work); flush_work(&unbind_work); break; } @@ -3500,18 +3642,17 @@ static int __devinit workqueue_cpu_down_callback(struct notifier_block *nfb, #ifdef CONFIG_SMP struct work_for_cpu { - struct completion completion; + struct work_struct work; long (*fn)(void *); void *arg; long ret; }; -static int do_work_for_cpu(void *_wfc) +static void work_for_cpu_fn(struct work_struct *work) { - struct work_for_cpu *wfc = _wfc; + struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work); + wfc->ret = wfc->fn(wfc->arg); - complete(&wfc->completion); - return 0; } /** @@ -3526,19 +3667,11 @@ static int do_work_for_cpu(void *_wfc) */ long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) { - struct task_struct *sub_thread; - struct work_for_cpu wfc = { - .completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion), - .fn = fn, - .arg = arg, - }; + struct work_for_cpu wfc = { .fn = fn, .arg = arg }; - sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu"); - if (IS_ERR(sub_thread)) - return PTR_ERR(sub_thread); - kthread_bind(sub_thread, cpu); - wake_up_process(sub_thread); - wait_for_completion(&wfc.completion); + INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn); + schedule_work_on(cpu, &wfc.work); + flush_work(&wfc.work); return wfc.ret; } EXPORT_SYMBOL_GPL(work_on_cpu); @@ -3668,11 +3801,7 @@ void thaw_workqueues(void) continue; /* 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); + cwq_set_max_active(cwq, wq->saved_max_active); } for_each_worker_pool(pool, gcwq) @@ -3692,8 +3821,12 @@ static int __init init_workqueues(void) unsigned int cpu; int i; + /* make sure we have enough bits for OFFQ CPU number */ + BUILD_BUG_ON((1LU << (BITS_PER_LONG - WORK_OFFQ_CPU_SHIFT)) < + WORK_CPU_LAST); + cpu_notifier(workqueue_cpu_up_callback, CPU_PRI_WORKQUEUE_UP); - cpu_notifier(workqueue_cpu_down_callback, CPU_PRI_WORKQUEUE_DOWN); + hotcpu_notifier(workqueue_cpu_down_callback, CPU_PRI_WORKQUEUE_DOWN); /* initialize gcwqs */ for_each_gcwq_cpu(cpu) { @@ -3719,11 +3852,9 @@ static int __init init_workqueues(void) setup_timer(&pool->mayday_timer, gcwq_mayday_timeout, (unsigned long)pool); - mutex_init(&pool->manager_mutex); + mutex_init(&pool->assoc_mutex); ida_init(&pool->worker_ida); } - - init_waitqueue_head(&gcwq->rebind_hold); } /* create the initial worker */ @@ -3746,17 +3877,14 @@ static int __init init_workqueues(void) } system_wq = alloc_workqueue("events", 0, 0); + system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0); system_long_wq = alloc_workqueue("events_long", 0, 0); - system_nrt_wq = alloc_workqueue("events_nrt", WQ_NON_REENTRANT, 0); system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, WQ_UNBOUND_MAX_ACTIVE); system_freezable_wq = alloc_workqueue("events_freezable", WQ_FREEZABLE, 0); - system_nrt_freezable_wq = alloc_workqueue("events_nrt_freezable", - WQ_NON_REENTRANT | WQ_FREEZABLE, 0); - BUG_ON(!system_wq || !system_long_wq || !system_nrt_wq || - !system_unbound_wq || !system_freezable_wq || - !system_nrt_freezable_wq); + BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq || + !system_unbound_wq || !system_freezable_wq); return 0; } early_initcall(init_workqueues); |