Messages in this thread Patch in this message | | | From | Tejun Heo <> | Subject | [PATCH 15/19] workqueue: kill cpu_populated_map | Date | Fri, 20 Nov 2009 13:46:43 +0900 |
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Single threaded workqueue is scheduled to be reimplemented in the near future. Kill cpu_populated_map and make single threaded workqueues behave more like multi threaded ones - all cwqs are initialized and all workqueues are linked on the workqueues list. This will ease further changes.
While at it, make get_cwq() always return the cwq for the specified cpu, add target_cwq() for cases where single thread distinction is necessary and drop all direct usage of per_cpu_ptr() on wq->cpu_wq.
Signed-off-by: Tejun Heo <tj@kernel.org> --- kernel/workqueue.c | 135 +++++++++++++++++++-------------------------------- 1 files changed, 50 insertions(+), 85 deletions(-)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 5392939..a255f43 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -191,15 +191,6 @@ static DEFINE_SPINLOCK(workqueue_lock); static LIST_HEAD(workqueues); static int singlethread_cpu __read_mostly; -static const struct cpumask *cpu_singlethread_map __read_mostly; -/* - * _cpu_down() first removes CPU from cpu_online_map, then CPU_DEAD - * flushes cwq->worklist. This means that flush_workqueue/wait_on_work - * which comes in between can't use for_each_online_cpu(). We could - * use cpu_possible_map, the cpumask below is more a documentation - * than optimization. - */ -static cpumask_var_t cpu_populated_map __read_mostly; /* If it's single threaded, it isn't in the list of workqueues. */ static inline bool is_wq_single_threaded(struct workqueue_struct *wq) @@ -207,18 +198,18 @@ static inline bool is_wq_single_threaded(struct workqueue_struct *wq) return wq->flags & WQ_SINGLE_THREAD; } -static const struct cpumask *wq_cpu_map(struct workqueue_struct *wq) +static struct cpu_workqueue_struct *get_cwq(unsigned int cpu, + struct workqueue_struct *wq) { - return is_wq_single_threaded(wq) - ? cpu_singlethread_map : cpu_populated_map; + return per_cpu_ptr(wq->cpu_wq, cpu); } -static struct cpu_workqueue_struct *get_cwq(unsigned int cpu, - struct workqueue_struct *wq) +static struct cpu_workqueue_struct *target_cwq(unsigned int cpu, + struct workqueue_struct *wq) { if (unlikely(is_wq_single_threaded(wq))) cpu = singlethread_cpu; - return per_cpu_ptr(wq->cpu_wq, cpu); + return get_cwq(cpu, wq); } /* @@ -274,7 +265,7 @@ static void insert_work(struct cpu_workqueue_struct *cwq, static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, struct work_struct *work) { - struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); + struct cpu_workqueue_struct *cwq = target_cwq(cpu, wq); unsigned long flags; debug_work_activate(work); @@ -378,7 +369,7 @@ int queue_delayed_work_on(int cpu, struct workqueue_struct *wq, timer_stats_timer_set_start_info(&dwork->timer); /* This stores cwq for the moment, for the timer_fn */ - set_wq_data(work, get_cwq(raw_smp_processor_id(), wq), 0); + set_wq_data(work, target_cwq(raw_smp_processor_id(), wq), 0); timer->expires = jiffies + delay; timer->data = (unsigned long)dwork; timer->function = delayed_work_timer_fn; @@ -569,14 +560,13 @@ static int flush_cpu_workqueue(struct cpu_workqueue_struct *cwq) */ void flush_workqueue(struct workqueue_struct *wq) { - const struct cpumask *cpu_map = wq_cpu_map(wq); int cpu; might_sleep(); lock_map_acquire(&wq->lockdep_map); lock_map_release(&wq->lockdep_map); - for_each_cpu(cpu, cpu_map) - flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, cpu)); + for_each_possible_cpu(cpu) + flush_cpu_workqueue(get_cwq(cpu, wq)); } EXPORT_SYMBOL_GPL(flush_workqueue); @@ -694,7 +684,6 @@ static void wait_on_work(struct work_struct *work) { struct cpu_workqueue_struct *cwq; struct workqueue_struct *wq; - const struct cpumask *cpu_map; int cpu; might_sleep(); @@ -707,9 +696,8 @@ static void wait_on_work(struct work_struct *work) return; wq = cwq->wq; - cpu_map = wq_cpu_map(wq); - for_each_cpu(cpu, cpu_map) + for_each_possible_cpu(cpu) wait_on_cpu_work(get_cwq(cpu, wq), work); } @@ -942,7 +930,7 @@ int current_is_keventd(void) BUG_ON(!keventd_wq); - cwq = per_cpu_ptr(keventd_wq->cpu_wq, cpu); + cwq = get_cwq(cpu, keventd_wq); if (current == cwq->thread) ret = 1; @@ -950,19 +938,6 @@ int current_is_keventd(void) } -static struct cpu_workqueue_struct * -init_cpu_workqueue(struct workqueue_struct *wq, int cpu) -{ - struct cpu_workqueue_struct *cwq = per_cpu_ptr(wq->cpu_wq, cpu); - - cwq->wq = wq; - spin_lock_init(&cwq->lock); - INIT_LIST_HEAD(&cwq->worklist); - init_waitqueue_head(&cwq->more_work); - - return cwq; -} - static int create_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu) { struct workqueue_struct *wq = cwq->wq; @@ -1001,8 +976,8 @@ struct workqueue_struct *__create_workqueue_key(const char *name, struct lock_class_key *key, const char *lock_name) { + bool singlethread = flags & WQ_SINGLE_THREAD; struct workqueue_struct *wq; - struct cpu_workqueue_struct *cwq; int err = 0, cpu; wq = kzalloc(sizeof(*wq), GFP_KERNEL); @@ -1018,36 +993,38 @@ struct workqueue_struct *__create_workqueue_key(const char *name, lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); INIT_LIST_HEAD(&wq->list); - if (flags & WQ_SINGLE_THREAD) { - cwq = init_cpu_workqueue(wq, singlethread_cpu); - err = create_workqueue_thread(cwq, singlethread_cpu); - start_workqueue_thread(cwq, -1); - } else { - cpu_maps_update_begin(); - /* - * We must place this wq on list even if the code below fails. - * cpu_down(cpu) can remove cpu from cpu_populated_map before - * destroy_workqueue() takes the lock, in that case we leak - * cwq[cpu]->thread. - */ - spin_lock(&workqueue_lock); - list_add(&wq->list, &workqueues); - spin_unlock(&workqueue_lock); - /* - * We must initialize cwqs for each possible cpu even if we - * are going to call destroy_workqueue() finally. Otherwise - * cpu_up() can hit the uninitialized cwq once we drop the - * lock. - */ - for_each_possible_cpu(cpu) { - cwq = init_cpu_workqueue(wq, cpu); - if (err || !cpu_online(cpu)) - continue; - err = create_workqueue_thread(cwq, cpu); - start_workqueue_thread(cwq, cpu); - } - cpu_maps_update_done(); + cpu_maps_update_begin(); + /* + * We must place this wq on list even if the code below fails. + * cpu_down(cpu) can remove cpu from cpu_populated_map before + * destroy_workqueue() takes the lock, in that case we leak + * cwq[cpu]->thread. + */ + spin_lock(&workqueue_lock); + list_add(&wq->list, &workqueues); + spin_unlock(&workqueue_lock); + /* + * We must initialize cwqs for each possible cpu even if we + * are going to call destroy_workqueue() finally. Otherwise + * cpu_up() can hit the uninitialized cwq once we drop the + * lock. + */ + for_each_possible_cpu(cpu) { + struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); + + cwq->wq = wq; + spin_lock_init(&cwq->lock); + INIT_LIST_HEAD(&cwq->worklist); + init_waitqueue_head(&cwq->more_work); + + if (err || !cpu_online(cpu)) + continue; + if (singlethread && cpu != singlethread_cpu) + continue; + err = create_workqueue_thread(cwq, cpu); + start_workqueue_thread(cwq, singlethread ? -1 : cpu); } + cpu_maps_update_done(); if (err) { destroy_workqueue(wq); @@ -1098,7 +1075,6 @@ static void cleanup_workqueue_thread(struct cpu_workqueue_struct *cwq) */ void destroy_workqueue(struct workqueue_struct *wq) { - const struct cpumask *cpu_map = wq_cpu_map(wq); int cpu; cpu_maps_update_begin(); @@ -1106,8 +1082,8 @@ void destroy_workqueue(struct workqueue_struct *wq) list_del(&wq->list); spin_unlock(&workqueue_lock); - for_each_cpu(cpu, cpu_map) - cleanup_workqueue_thread(per_cpu_ptr(wq->cpu_wq, cpu)); + for_each_possible_cpu(cpu) + cleanup_workqueue_thread(get_cwq(cpu, wq)); cpu_maps_update_done(); free_percpu(wq->cpu_wq); @@ -1126,13 +1102,12 @@ static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, action &= ~CPU_TASKS_FROZEN; - switch (action) { - case CPU_UP_PREPARE: - cpumask_set_cpu(cpu, cpu_populated_map); - } undo: list_for_each_entry(wq, &workqueues, list) { - cwq = per_cpu_ptr(wq->cpu_wq, cpu); + if (is_wq_single_threaded(wq)) + continue; + + cwq = get_cwq(cpu, wq); switch (action) { case CPU_UP_PREPARE: @@ -1156,12 +1131,6 @@ undo: } } - switch (action) { - case CPU_UP_CANCELED: - case CPU_POST_DEAD: - cpumask_clear_cpu(cpu, cpu_populated_map); - } - return ret; } @@ -1223,11 +1192,7 @@ void __init init_workqueues(void) BUILD_BUG_ON(__alignof__(struct cpu_workqueue_struct) < __alignof__(unsigned long long)); - alloc_cpumask_var(&cpu_populated_map, GFP_KERNEL); - - cpumask_copy(cpu_populated_map, cpu_online_mask); singlethread_cpu = cpumask_first(cpu_possible_mask); - cpu_singlethread_map = cpumask_of(singlethread_cpu); hotcpu_notifier(workqueue_cpu_callback, 0); keventd_wq = create_workqueue("events"); BUG_ON(!keventd_wq); -- 1.6.4.2
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