X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=kernel%2Fworkqueue.c;h=12328147132c0e6e560ff2e3de39c2fda2a4f116;hb=1d510750941a53a1d3049c1d33c75d6dfcd78618;hp=d7d3fa3072e5941c7fc5d5757963b011823b93d5;hpb=1f1f642e2f092e37eb9038060eb0100c44f55a11;p=safe%2Fjmp%2Flinux-2.6 diff --git a/kernel/workqueue.c b/kernel/workqueue.c index d7d3fa3..1232814 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -9,11 +9,11 @@ * Derived from the taskqueue/keventd code by: * * David Woodhouse - * Andrew Morton + * Andrew Morton * Kai Petzke * Theodore Ts'o * - * Made to use alloc_percpu by Christoph Lameter . + * Made to use alloc_percpu by Christoph Lameter. */ #include @@ -32,6 +32,9 @@ #include #include #include +#include +#define CREATE_TRACE_POINTS +#include /* * The per-CPU workqueue (if single thread, we always use the first @@ -47,8 +50,6 @@ struct cpu_workqueue_struct { struct workqueue_struct *wq; struct task_struct *thread; - - int run_depth; /* Detect run_workqueue() recursion depth */ } ____cacheline_aligned; /* @@ -61,15 +62,18 @@ 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 }; -/* All the per-cpu workqueues on the system, for hotplug cpu to add/remove - threads to each one as cpus come/go. */ -static DEFINE_MUTEX(workqueue_mutex); +/* Serializes the accesses to the list of workqueues. */ +static DEFINE_SPINLOCK(workqueue_lock); static LIST_HEAD(workqueues); static int singlethread_cpu __read_mostly; -static cpumask_t cpu_singlethread_map __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 @@ -77,24 +81,24 @@ static cpumask_t cpu_singlethread_map __read_mostly; * use cpu_possible_map, the cpumask below is more a documentation * than optimization. */ -static cpumask_t cpu_populated_map __read_mostly; +static cpumask_var_t cpu_populated_map __read_mostly; /* If it's single threaded, it isn't in the list of workqueues. */ -static inline int is_single_threaded(struct workqueue_struct *wq) +static inline int is_wq_single_threaded(struct workqueue_struct *wq) { return wq->singlethread; } -static const cpumask_t *wq_cpu_map(struct workqueue_struct *wq) +static const struct cpumask *wq_cpu_map(struct workqueue_struct *wq) { - return is_single_threaded(wq) - ? &cpu_singlethread_map : &cpu_populated_map; + return is_wq_single_threaded(wq) + ? cpu_singlethread_map : cpu_populated_map; } static struct cpu_workqueue_struct *wq_per_cpu(struct workqueue_struct *wq, int cpu) { - if (unlikely(is_single_threaded(wq))) + if (unlikely(is_wq_single_threaded(wq))) cpu = singlethread_cpu; return per_cpu_ptr(wq->cpu_wq, cpu); } @@ -122,29 +126,27 @@ struct cpu_workqueue_struct *get_wq_data(struct work_struct *work) } static void insert_work(struct cpu_workqueue_struct *cwq, - struct work_struct *work, int tail) + struct work_struct *work, struct list_head *head) { + trace_workqueue_insertion(cwq->thread, work); + set_wq_data(work, cwq); /* * Ensure that we get the right work->data if we see the * result of list_add() below, see try_to_grab_pending(). */ smp_wmb(); - if (tail) - list_add_tail(&work->entry, &cwq->worklist); - else - list_add(&work->entry, &cwq->worklist); + list_add_tail(&work->entry, head); wake_up(&cwq->more_work); } -/* Preempt must be disabled. */ static void __queue_work(struct cpu_workqueue_struct *cwq, struct work_struct *work) { unsigned long flags; spin_lock_irqsave(&cwq->lock, flags); - insert_work(cwq, work, 1); + insert_work(cwq, work, &cwq->worklist); spin_unlock_irqrestore(&cwq->lock, flags); } @@ -155,24 +157,46 @@ static void __queue_work(struct cpu_workqueue_struct *cwq, * * Returns 0 if @work was already on a queue, non-zero otherwise. * - * We queue the work to the CPU it was submitted, but there is no - * guarantee that it will be processed by that CPU. + * 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(struct workqueue_struct *wq, struct work_struct *work) +{ + int ret; + + ret = queue_work_on(get_cpu(), wq, work); + put_cpu(); + + return ret; +} +EXPORT_SYMBOL_GPL(queue_work); + +/** + * 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. + * + * We queue the work to a specific CPU, the caller must ensure it + * can't go away. */ -int fastcall queue_work(struct workqueue_struct *wq, struct work_struct *work) +int +queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work) { int ret = 0; if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) { BUG_ON(!list_empty(&work->entry)); - __queue_work(wq_per_cpu(wq, get_cpu()), work); - put_cpu(); + __queue_work(wq_per_cpu(wq, cpu), work); ret = 1; } return ret; } -EXPORT_SYMBOL_GPL(queue_work); +EXPORT_SYMBOL_GPL(queue_work_on); -void delayed_work_timer_fn(unsigned long __data) +static void delayed_work_timer_fn(unsigned long __data) { struct delayed_work *dwork = (struct delayed_work *)__data; struct cpu_workqueue_struct *cwq = get_wq_data(&dwork->work); @@ -189,10 +213,9 @@ void delayed_work_timer_fn(unsigned long __data) * * Returns 0 if @work was already on a queue, non-zero otherwise. */ -int fastcall queue_delayed_work(struct workqueue_struct *wq, +int queue_delayed_work(struct workqueue_struct *wq, struct delayed_work *dwork, unsigned long delay) { - timer_stats_timer_set_start_info(&dwork->timer); if (delay == 0) return queue_work(wq, &dwork->work); @@ -220,6 +243,8 @@ int queue_delayed_work_on(int cpu, struct workqueue_struct *wq, BUG_ON(timer_pending(timer)); BUG_ON(!list_empty(&work->entry)); + timer_stats_timer_set_start_info(&dwork->timer); + /* This stores cwq for the moment, for the timer_fn */ set_wq_data(work, wq_per_cpu(wq, raw_smp_processor_id())); timer->expires = jiffies + delay; @@ -239,31 +264,39 @@ EXPORT_SYMBOL_GPL(queue_delayed_work_on); static void run_workqueue(struct cpu_workqueue_struct *cwq) { spin_lock_irq(&cwq->lock); - cwq->run_depth++; - if (cwq->run_depth > 3) { - /* morton gets to eat his hat */ - printk("%s: recursion depth exceeded: %d\n", - __FUNCTION__, cwq->run_depth); - dump_stack(); - } while (!list_empty(&cwq->worklist)) { struct work_struct *work = list_entry(cwq->worklist.next, struct work_struct, entry); work_func_t f = work->func; - +#ifdef CONFIG_LOCKDEP + /* + * It is permissible to free the struct work_struct + * from inside the function that is called from it, + * this we need to take into account for lockdep too. + * To avoid bogus "held lock freed" warnings as well + * as problems when looking into work->lockdep_map, + * make a copy and use that here. + */ + struct lockdep_map lockdep_map = work->lockdep_map; +#endif + trace_workqueue_execution(cwq->thread, work); cwq->current_work = work; list_del_init(cwq->worklist.next); spin_unlock_irq(&cwq->lock); BUG_ON(get_wq_data(work) != cwq); work_clear_pending(work); + lock_map_acquire(&cwq->wq->lockdep_map); + lock_map_acquire(&lockdep_map); f(work); + lock_map_release(&lockdep_map); + 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(), - current->pid); + task_pid_nr(current)); printk(KERN_ERR " last function: "); print_symbol("%s\n", (unsigned long)f); debug_show_held_locks(current); @@ -273,7 +306,6 @@ static void run_workqueue(struct cpu_workqueue_struct *cwq) spin_lock_irq(&cwq->lock); cwq->current_work = NULL; } - cwq->run_depth--; spin_unlock_irq(&cwq->lock); } @@ -282,10 +314,8 @@ static int worker_thread(void *__cwq) struct cpu_workqueue_struct *cwq = __cwq; DEFINE_WAIT(wait); - if (!cwq->wq->freezeable) - current->flags |= PF_NOFREEZE; - - set_user_nice(current, -5); + if (cwq->wq->freezeable) + set_freezable(); for (;;) { prepare_to_wait(&cwq->more_work, &wait, TASK_INTERRUPTIBLE); @@ -318,41 +348,32 @@ static void wq_barrier_func(struct work_struct *work) } static void insert_wq_barrier(struct cpu_workqueue_struct *cwq, - struct wq_barrier *barr, int tail) + struct wq_barrier *barr, struct list_head *head) { INIT_WORK(&barr->work, wq_barrier_func); __set_bit(WORK_STRUCT_PENDING, work_data_bits(&barr->work)); init_completion(&barr->done); - insert_work(cwq, &barr->work, tail); + insert_work(cwq, &barr->work, head); } static int flush_cpu_workqueue(struct cpu_workqueue_struct *cwq) { - int active; - - if (cwq->thread == current) { - /* - * Probably keventd trying to flush its own queue. So simply run - * it by hand rather than deadlocking. - */ - run_workqueue(cwq); - active = 1; - } else { - struct wq_barrier barr; + int active = 0; + struct wq_barrier barr; - active = 0; - spin_lock_irq(&cwq->lock); - if (!list_empty(&cwq->worklist) || cwq->current_work != NULL) { - insert_wq_barrier(cwq, &barr, 1); - active = 1; - } - spin_unlock_irq(&cwq->lock); + WARN_ON(cwq->thread == current); - if (active) - wait_for_completion(&barr.done); + spin_lock_irq(&cwq->lock); + if (!list_empty(&cwq->worklist) || cwq->current_work != NULL) { + insert_wq_barrier(cwq, &barr, &cwq->worklist); + active = 1; } + spin_unlock_irq(&cwq->lock); + + if (active) + wait_for_completion(&barr.done); return active; } @@ -370,17 +391,70 @@ static int flush_cpu_workqueue(struct cpu_workqueue_struct *cwq) * This function used to run the workqueues itself. Now we just wait for the * helper threads to do it. */ -void fastcall flush_workqueue(struct workqueue_struct *wq) +void flush_workqueue(struct workqueue_struct *wq) { - const cpumask_t *cpu_map = wq_cpu_map(wq); + const struct cpumask *cpu_map = wq_cpu_map(wq); int cpu; might_sleep(); - for_each_cpu_mask(cpu, *cpu_map) + 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)); } EXPORT_SYMBOL_GPL(flush_workqueue); +/** + * flush_work - block until a work_struct's callback has terminated + * @work: the work which is to be flushed + * + * Returns false if @work has already terminated. + * + * 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; + + lock_map_acquire(&cwq->wq->lockdep_map); + lock_map_release(&cwq->wq->lockdep_map); + + 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. @@ -428,7 +502,7 @@ static void wait_on_cpu_work(struct cpu_workqueue_struct *cwq, spin_lock_irq(&cwq->lock); if (unlikely(cwq->current_work == work)) { - insert_wq_barrier(cwq, &barr, 0); + insert_wq_barrier(cwq, &barr, cwq->worklist.next); running = 1; } spin_unlock_irq(&cwq->lock); @@ -441,11 +515,14 @@ static void wait_on_work(struct work_struct *work) { struct cpu_workqueue_struct *cwq; struct workqueue_struct *wq; - const cpumask_t *cpu_map; + const struct cpumask *cpu_map; int cpu; might_sleep(); + lock_map_acquire(&work->lockdep_map); + lock_map_release(&work->lockdep_map); + cwq = get_wq_data(work); if (!cwq) return; @@ -453,7 +530,7 @@ static void wait_on_work(struct work_struct *work) wq = cwq->wq; cpu_map = wq_cpu_map(wq); - for_each_cpu_mask(cpu, *cpu_map) + for_each_cpu(cpu, cpu_map) wait_on_cpu_work(per_cpu_ptr(wq->cpu_wq, cpu), work); } @@ -521,14 +598,32 @@ static struct workqueue_struct *keventd_wq __read_mostly; * schedule_work - put work task in global workqueue * @work: job to be done * - * This puts a job in the kernel-global workqueue. + * 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 fastcall schedule_work(struct work_struct *work) +int schedule_work(struct work_struct *work) { return queue_work(keventd_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) +{ + return queue_work_on(cpu, keventd_wq, work); +} +EXPORT_SYMBOL(schedule_work_on); + /** * schedule_delayed_work - put work task in global workqueue after delay * @dwork: job to be done @@ -537,15 +632,32 @@ EXPORT_SYMBOL(schedule_work); * After waiting for a given time this puts a job in the kernel-global * workqueue. */ -int fastcall schedule_delayed_work(struct delayed_work *dwork, +int schedule_delayed_work(struct delayed_work *dwork, unsigned long delay) { - timer_stats_timer_set_start_info(&dwork->timer); return queue_delayed_work(keventd_wq, dwork, delay); } EXPORT_SYMBOL(schedule_delayed_work); /** + * flush_delayed_work - block until a dwork_struct's callback has terminated + * @dwork: the delayed work which is to be flushed + * + * Any timeout is cancelled, and any pending work is run immediately. + */ +void flush_delayed_work(struct delayed_work *dwork) +{ + if (del_timer_sync(&dwork->timer)) { + struct cpu_workqueue_struct *cwq; + cwq = wq_per_cpu(keventd_wq, get_cpu()); + __queue_work(cwq, &dwork->work); + put_cpu(); + } + flush_work(&dwork->work); +} +EXPORT_SYMBOL(flush_delayed_work); + +/** * schedule_delayed_work_on - queue work in global workqueue on CPU after delay * @cpu: cpu to use * @dwork: job to be done @@ -568,29 +680,44 @@ EXPORT_SYMBOL(schedule_delayed_work_on); * Returns zero on success. * Returns -ve errno on failure. * - * Appears to be racy against CPU hotplug. - * * schedule_on_each_cpu() is very slow. */ int schedule_on_each_cpu(work_func_t func) { int cpu; + int orig = -1; struct work_struct *works; works = alloc_percpu(struct work_struct); if (!works) return -ENOMEM; - preempt_disable(); /* CPU hotplug */ + /* + * when running in keventd don't schedule a work item on itself. + * Can just call directly because the work queue is already bound. + * This also is faster. + * Make this a generic parameter for other workqueues? + */ + if (current_is_keventd()) { + orig = raw_smp_processor_id(); + INIT_WORK(per_cpu_ptr(works, orig), func); + func(per_cpu_ptr(works, orig)); + } + + get_online_cpus(); for_each_online_cpu(cpu) { struct work_struct *work = per_cpu_ptr(works, cpu); + if (cpu == orig) + continue; INIT_WORK(work, func); - set_bit(WORK_STRUCT_PENDING, work_data_bits(work)); - __queue_work(per_cpu_ptr(keventd_wq->cpu_wq, cpu), work); + schedule_work_on(cpu, work); } - preempt_enable(); - flush_workqueue(keventd_wq); + for_each_online_cpu(cpu) { + if (cpu != orig) + flush_work(per_cpu_ptr(works, cpu)); + } + put_online_cpus(); free_percpu(works); return 0; } @@ -635,7 +762,7 @@ int keventd_up(void) int current_is_keventd(void) { struct cpu_workqueue_struct *cwq; - int cpu = smp_processor_id(); /* preempt-safe: keventd is per-cpu */ + int cpu = raw_smp_processor_id(); /* preempt-safe: keventd is per-cpu */ int ret = 0; BUG_ON(!keventd_wq); @@ -663,8 +790,9 @@ 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"; + const char *fmt = is_wq_single_threaded(wq) ? "%s" : "%s/%d"; struct task_struct *p; p = kthread_create(worker_thread, cwq, fmt, wq->name, cpu); @@ -678,9 +806,12 @@ 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; + trace_workqueue_creation(cwq->thread, cpu); + return 0; } @@ -695,8 +826,12 @@ static void start_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu) } } -struct workqueue_struct *__create_workqueue(const char *name, - int singlethread, int freezeable) +struct workqueue_struct *__create_workqueue_key(const char *name, + int singlethread, + int freezeable, + int rt, + struct lock_class_key *key, + const char *lock_name) { struct workqueue_struct *wq; struct cpu_workqueue_struct *cwq; @@ -713,8 +848,10 @@ struct workqueue_struct *__create_workqueue(const char *name, } wq->name = 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) { @@ -722,9 +859,22 @@ struct workqueue_struct *__create_workqueue(const char *name, err = create_workqueue_thread(cwq, singlethread_cpu); start_workqueue_thread(cwq, -1); } else { - mutex_lock(&workqueue_mutex); + 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)) @@ -732,7 +882,7 @@ struct workqueue_struct *__create_workqueue(const char *name, err = create_workqueue_thread(cwq, cpu); start_workqueue_thread(cwq, cpu); } - mutex_unlock(&workqueue_mutex); + cpu_maps_update_done(); } if (err) { @@ -741,29 +891,32 @@ struct workqueue_struct *__create_workqueue(const char *name, } return wq; } -EXPORT_SYMBOL_GPL(__create_workqueue); +EXPORT_SYMBOL_GPL(__create_workqueue_key); -static void cleanup_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu) +static void cleanup_workqueue_thread(struct cpu_workqueue_struct *cwq) { /* - * Our caller is either destroy_workqueue() or CPU_DEAD, - * workqueue_mutex protects cwq->thread + * Our caller is either destroy_workqueue() or CPU_POST_DEAD, + * cpu_add_remove_lock protects cwq->thread. */ if (cwq->thread == NULL) return; + lock_map_acquire(&cwq->wq->lockdep_map); + lock_map_release(&cwq->wq->lockdep_map); + + flush_cpu_workqueue(cwq); /* - * If the caller is CPU_DEAD the single flush_cpu_workqueue() - * is not enough, a concurrent flush_workqueue() can insert a - * barrier after us. + * If the caller is CPU_POST_DEAD and cwq->worklist was not empty, + * a concurrent flush_workqueue() can insert a barrier after us. + * However, in that case run_workqueue() won't return and check + * kthread_should_stop() until it flushes all work_struct's. * When ->worklist becomes empty it is safe to exit because no * more work_structs can be queued on this cwq: flush_workqueue * checks list_empty(), and a "normal" queue_work() can't use * a dead CPU. */ - while (flush_cpu_workqueue(cwq)) - ; - + trace_workqueue_destruction(cwq->thread); kthread_stop(cwq->thread); cwq->thread = NULL; } @@ -776,18 +929,17 @@ static void cleanup_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu) */ void destroy_workqueue(struct workqueue_struct *wq) { - const cpumask_t *cpu_map = wq_cpu_map(wq); - struct cpu_workqueue_struct *cwq; + const struct cpumask *cpu_map = wq_cpu_map(wq); int cpu; - mutex_lock(&workqueue_mutex); + cpu_maps_update_begin(); + spin_lock(&workqueue_lock); list_del(&wq->list); - mutex_unlock(&workqueue_mutex); + spin_unlock(&workqueue_lock); - for_each_cpu_mask(cpu, *cpu_map) { - cwq = per_cpu_ptr(wq->cpu_wq, cpu); - cleanup_workqueue_thread(cwq, cpu); - } + for_each_cpu(cpu, cpu_map) + cleanup_workqueue_thread(per_cpu_ptr(wq->cpu_wq, cpu)); + cpu_maps_update_done(); free_percpu(wq->cpu_wq); kfree(wq); @@ -801,22 +953,15 @@ static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, unsigned int cpu = (unsigned long)hcpu; struct cpu_workqueue_struct *cwq; struct workqueue_struct *wq; + int ret = NOTIFY_OK; action &= ~CPU_TASKS_FROZEN; switch (action) { - case CPU_LOCK_ACQUIRE: - mutex_lock(&workqueue_mutex); - return NOTIFY_OK; - - case CPU_LOCK_RELEASE: - mutex_unlock(&workqueue_mutex); - return NOTIFY_OK; - case CPU_UP_PREPARE: - cpu_set(cpu, cpu_populated_map); + cpumask_set_cpu(cpu, cpu_populated_map); } - +undo: list_for_each_entry(wq, &workqueues, list) { cwq = per_cpu_ptr(wq->cpu_wq, cpu); @@ -824,8 +969,11 @@ static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, case CPU_UP_PREPARE: if (!create_workqueue_thread(cwq, cpu)) break; - printk(KERN_ERR "workqueue for %i failed\n", cpu); - return NOTIFY_BAD; + printk(KERN_ERR "workqueue [%s] for %i failed\n", + wq->name, cpu); + action = CPU_UP_CANCELED; + ret = NOTIFY_BAD; + goto undo; case CPU_ONLINE: start_workqueue_thread(cwq, cpu); @@ -833,20 +981,75 @@ static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, case CPU_UP_CANCELED: start_workqueue_thread(cwq, -1); - case CPU_DEAD: - cleanup_workqueue_thread(cwq, cpu); + case CPU_POST_DEAD: + cleanup_workqueue_thread(cwq); break; } } - return NOTIFY_OK; + switch (action) { + case CPU_UP_CANCELED: + case CPU_POST_DEAD: + cpumask_clear_cpu(cpu, cpu_populated_map); + } + + return ret; +} + +#ifdef CONFIG_SMP + +struct work_for_cpu { + struct completion completion; + long (*fn)(void *); + void *arg; + long ret; +}; + +static int do_work_for_cpu(void *_wfc) +{ + struct work_for_cpu *wfc = _wfc; + wfc->ret = wfc->fn(wfc->arg); + complete(&wfc->completion); + return 0; } +/** + * work_on_cpu - run a function in user context on a particular cpu + * @cpu: the cpu to run on + * @fn: the function to run + * @arg: the function arg + * + * This will return the value @fn returns. + * It is up to the caller to ensure that the cpu doesn't go offline. + * The caller must not hold any locks which would prevent @fn from completing. + */ +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, + }; + + 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); + return wfc.ret; +} +EXPORT_SYMBOL_GPL(work_on_cpu); +#endif /* CONFIG_SMP */ + void __init init_workqueues(void) { - cpu_populated_map = cpu_online_map; - singlethread_cpu = first_cpu(cpu_possible_map); - cpu_singlethread_map = cpumask_of_cpu(singlethread_cpu); + 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);