| /* |
| * linux/kernel/workqueue.c |
| * |
| * Generic mechanism for defining kernel helper threads for running |
| * arbitrary tasks in process context. |
| * |
| * Started by Ingo Molnar, Copyright (C) 2002 |
| * |
| * Derived from the taskqueue/keventd code by: |
| * |
| * David Woodhouse <dwmw2@infradead.org> |
| * Andrew Morton |
| * Kai Petzke <wpp@marie.physik.tu-berlin.de> |
| * Theodore Ts'o <tytso@mit.edu> |
| * |
| * Made to use alloc_percpu by Christoph Lameter. |
| */ |
| |
| #include <linux/module.h> |
| #include <linux/kernel.h> |
| #include <linux/sched.h> |
| #include <linux/init.h> |
| #include <linux/signal.h> |
| #include <linux/completion.h> |
| #include <linux/workqueue.h> |
| #include <linux/slab.h> |
| #include <linux/cpu.h> |
| #include <linux/notifier.h> |
| #include <linux/kthread.h> |
| #include <linux/hardirq.h> |
| #include <linux/mempolicy.h> |
| #include <linux/freezer.h> |
| #include <linux/kallsyms.h> |
| #include <linux/debug_locks.h> |
| #include <linux/lockdep.h> |
| #define CREATE_TRACE_POINTS |
| #include <trace/events/workqueue.h> |
| |
| /* |
| * The per-CPU workqueue (if single thread, we always use the first |
| * possible cpu). |
| */ |
| struct cpu_workqueue_struct { |
| |
| spinlock_t lock; |
| |
| struct list_head worklist; |
| wait_queue_head_t more_work; |
| struct work_struct *current_work; |
| |
| struct workqueue_struct *wq; |
| struct task_struct *thread; |
| } ____cacheline_aligned; |
| |
| /* |
| * The externally visible workqueue abstraction is an array of |
| * per-CPU workqueues: |
| */ |
| struct workqueue_struct { |
| struct cpu_workqueue_struct *cpu_wq; |
| struct list_head list; |
| const char *name; |
| int singlethread; |
| int freezeable; /* Freeze threads during suspend */ |
| int rt; |
| #ifdef CONFIG_LOCKDEP |
| struct lockdep_map lockdep_map; |
| #endif |
| }; |
| |
| /* Serializes the accesses to the list of workqueues. */ |
| 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 int is_wq_single_threaded(struct workqueue_struct *wq) |
| { |
| return wq->singlethread; |
| } |
| |
| static const struct cpumask *wq_cpu_map(struct workqueue_struct *wq) |
| { |
| 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_wq_single_threaded(wq))) |
| cpu = singlethread_cpu; |
| return per_cpu_ptr(wq->cpu_wq, cpu); |
| } |
| |
| /* |
| * Set the workqueue on which a work item is to be run |
| * - Must *only* be called if the pending flag is set |
| */ |
| static inline void set_wq_data(struct work_struct *work, |
| struct cpu_workqueue_struct *cwq) |
| { |
| unsigned long new; |
| |
| BUG_ON(!work_pending(work)); |
| |
| new = (unsigned long) cwq | (1UL << WORK_STRUCT_PENDING); |
| new |= WORK_STRUCT_FLAG_MASK & *work_data_bits(work); |
| atomic_long_set(&work->data, new); |
| } |
| |
| static inline |
| struct cpu_workqueue_struct *get_wq_data(struct work_struct *work) |
| { |
| return (void *) (atomic_long_read(&work->data) & WORK_STRUCT_WQ_DATA_MASK); |
| } |
| |
| static void insert_work(struct cpu_workqueue_struct *cwq, |
| 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(); |
| list_add_tail(&work->entry, head); |
| wake_up(&cwq->more_work); |
| } |
| |
| 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, &cwq->worklist); |
| spin_unlock_irqrestore(&cwq->lock, flags); |
| } |
| |
| /** |
| * 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. |
| * |
| * 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 |
| 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, cpu), work); |
| ret = 1; |
| } |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(queue_work_on); |
| |
| 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); |
| struct workqueue_struct *wq = cwq->wq; |
| |
| __queue_work(wq_per_cpu(wq, smp_processor_id()), &dwork->work); |
| } |
| |
| /** |
| * 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) |
| { |
| if (delay == 0) |
| return queue_work(wq, &dwork->work); |
| |
| return queue_delayed_work_on(-1, wq, dwork, delay); |
| } |
| EXPORT_SYMBOL_GPL(queue_delayed_work); |
| |
| /** |
| * queue_delayed_work_on - queue work on specific CPU after delay |
| * @cpu: CPU number to execute work on |
| * @wq: workqueue to use |
| * @dwork: 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_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; |
| |
| if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) { |
| 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; |
| timer->data = (unsigned long)dwork; |
| timer->function = delayed_work_timer_fn; |
| |
| if (unlikely(cpu >= 0)) |
| add_timer_on(timer, cpu); |
| else |
| add_timer(timer); |
| ret = 1; |
| } |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(queue_delayed_work_on); |
| |
| static void run_workqueue(struct cpu_workqueue_struct *cwq) |
| { |
| spin_lock_irq(&cwq->lock); |
| 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(), |
| task_pid_nr(current)); |
| printk(KERN_ERR " last function: "); |
| print_symbol("%s\n", (unsigned long)f); |
| debug_show_held_locks(current); |
| dump_stack(); |
| } |
| |
| spin_lock_irq(&cwq->lock); |
| cwq->current_work = NULL; |
| } |
| spin_unlock_irq(&cwq->lock); |
| } |
| |
| static int worker_thread(void *__cwq) |
| { |
| struct cpu_workqueue_struct *cwq = __cwq; |
| DEFINE_WAIT(wait); |
| |
| if (cwq->wq->freezeable) |
| set_freezable(); |
| |
| for (;;) { |
| prepare_to_wait(&cwq->more_work, &wait, TASK_INTERRUPTIBLE); |
| if (!freezing(current) && |
| !kthread_should_stop() && |
| list_empty(&cwq->worklist)) |
| schedule(); |
| finish_wait(&cwq->more_work, &wait); |
| |
| try_to_freeze(); |
| |
| if (kthread_should_stop()) |
| break; |
| |
| run_workqueue(cwq); |
| } |
| |
| return 0; |
| } |
| |
| struct wq_barrier { |
| struct work_struct work; |
| struct completion done; |
| }; |
| |
| static void wq_barrier_func(struct work_struct *work) |
| { |
| struct wq_barrier *barr = container_of(work, struct wq_barrier, work); |
| complete(&barr->done); |
| } |
| |
| static void insert_wq_barrier(struct cpu_workqueue_struct *cwq, |
| 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, head); |
| } |
| |
| static int flush_cpu_workqueue(struct cpu_workqueue_struct *cwq) |
| { |
| int active = 0; |
| struct wq_barrier barr; |
| |
| WARN_ON(cwq->thread == current); |
| |
| 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; |
| } |
| |
| /** |
| * flush_workqueue - ensure that any scheduled work has run to completion. |
| * @wq: workqueue to flush |
| * |
| * Forces execution of the workqueue and blocks until its completion. |
| * This is typically used in driver shutdown handlers. |
| * |
| * We sleep until all works which were queued on entry have been handled, |
| * but we are not livelocked by new incoming ones. |
| * |
| * This function used to run the workqueues itself. Now we just wait for the |
| * helper threads to do it. |
| */ |
| 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)); |
| } |
| 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. |
| */ |
| static int try_to_grab_pending(struct work_struct *work) |
| { |
| struct cpu_workqueue_struct *cwq; |
| int ret = -1; |
| |
| if (!test_and_set_bit(WORK_STRUCT_PENDING, 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. |
| */ |
| |
| cwq = get_wq_data(work); |
| if (!cwq) |
| return ret; |
| |
| spin_lock_irq(&cwq->lock); |
| if (!list_empty(&work->entry)) { |
| /* |
| * This work is queued, but perhaps we locked the wrong cwq. |
| * In that case we must see the new value after rmb(), see |
| * insert_work()->wmb(). |
| */ |
| smp_rmb(); |
| if (cwq == get_wq_data(work)) { |
| list_del_init(&work->entry); |
| ret = 1; |
| } |
| } |
| spin_unlock_irq(&cwq->lock); |
| |
| return ret; |
| } |
| |
| static void wait_on_cpu_work(struct cpu_workqueue_struct *cwq, |
| struct work_struct *work) |
| { |
| struct wq_barrier barr; |
| int running = 0; |
| |
| spin_lock_irq(&cwq->lock); |
| if (unlikely(cwq->current_work == work)) { |
| insert_wq_barrier(cwq, &barr, cwq->worklist.next); |
| running = 1; |
| } |
| spin_unlock_irq(&cwq->lock); |
| |
| if (unlikely(running)) |
| wait_for_completion(&barr.done); |
| } |
| |
| 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(); |
| |
| lock_map_acquire(&work->lockdep_map); |
| lock_map_release(&work->lockdep_map); |
| |
| cwq = get_wq_data(work); |
| if (!cwq) |
| return; |
| |
| wq = cwq->wq; |
| cpu_map = wq_cpu_map(wq); |
| |
| for_each_cpu(cpu, cpu_map) |
| wait_on_cpu_work(per_cpu_ptr(wq->cpu_wq, cpu), work); |
| } |
| |
| static int __cancel_work_timer(struct work_struct *work, |
| struct timer_list* timer) |
| { |
| int ret; |
| |
| do { |
| ret = (timer && likely(del_timer(timer))); |
| if (!ret) |
| ret = try_to_grab_pending(work); |
| wait_on_work(work); |
| } while (unlikely(ret < 0)); |
| |
| work_clear_pending(work); |
| return ret; |
| } |
| |
| /** |
| * cancel_work_sync - block until a work_struct's callback has terminated |
| * @work: the work which is to be flushed |
| * |
| * Returns true if @work was pending. |
| * |
| * cancel_work_sync() will cancel the work if it is queued. If the work's |
| * callback appears to be running, cancel_work_sync() will block until it |
| * has completed. |
| * |
| * It is possible to use this function if the work re-queues itself. It can |
| * cancel the work even if it migrates to another workqueue, however in that |
| * case it only guarantees that work->func() has completed on the last queued |
| * workqueue. |
| * |
| * cancel_work_sync(&delayed_work->work) should be used only if ->timer is not |
| * pending, otherwise it goes into a busy-wait loop until the timer expires. |
| * |
| * The caller must ensure that workqueue_struct on which this work was last |
| * queued can't be destroyed before this function returns. |
| */ |
| int cancel_work_sync(struct work_struct *work) |
| { |
| return __cancel_work_timer(work, NULL); |
| } |
| EXPORT_SYMBOL_GPL(cancel_work_sync); |
| |
| /** |
| * cancel_delayed_work_sync - reliably kill off a delayed work. |
| * @dwork: the delayed work struct |
| * |
| * Returns true if @dwork was pending. |
| * |
| * It is possible to use this function if @dwork rearms itself via queue_work() |
| * or queue_delayed_work(). See also the comment for cancel_work_sync(). |
| */ |
| int cancel_delayed_work_sync(struct delayed_work *dwork) |
| { |
| return __cancel_work_timer(&dwork->work, &dwork->timer); |
| } |
| EXPORT_SYMBOL(cancel_delayed_work_sync); |
| |
| static struct workqueue_struct *keventd_wq __read_mostly; |
| |
| /** |
| * 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(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 |
| * @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. |
| */ |
| int schedule_delayed_work(struct delayed_work *dwork, |
| unsigned long delay) |
| { |
| 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(&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 |
| * @delay: number of jiffies to wait |
| * |
| * 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) |
| { |
| return queue_delayed_work_on(cpu, keventd_wq, dwork, delay); |
| } |
| EXPORT_SYMBOL(schedule_delayed_work_on); |
| |
| /** |
| * schedule_on_each_cpu - call a function on each online CPU from keventd |
| * @func: the function to call |
| * |
| * Returns zero on success. |
| * Returns -ve errno on failure. |
| * |
| * schedule_on_each_cpu() is very slow. |
| */ |
| int schedule_on_each_cpu(work_func_t func) |
| { |
| int cpu; |
| struct work_struct *works; |
| |
| works = alloc_percpu(struct work_struct); |
| if (!works) |
| return -ENOMEM; |
| |
| get_online_cpus(); |
| for_each_online_cpu(cpu) { |
| struct work_struct *work = per_cpu_ptr(works, cpu); |
| |
| INIT_WORK(work, func); |
| schedule_work_on(cpu, work); |
| } |
| for_each_online_cpu(cpu) |
| flush_work(per_cpu_ptr(works, cpu)); |
| put_online_cpus(); |
| free_percpu(works); |
| return 0; |
| } |
| |
| void flush_scheduled_work(void) |
| { |
| flush_workqueue(keventd_wq); |
| } |
| EXPORT_SYMBOL(flush_scheduled_work); |
| |
| /** |
| * execute_in_process_context - reliably execute the routine with user context |
| * @fn: the function to execute |
| * @ew: guaranteed storage for the execute work structure (must |
| * be available when the work executes) |
| * |
| * Executes the function immediately if process context is available, |
| * otherwise schedules the function for delayed execution. |
| * |
| * Returns: 0 - function was executed |
| * 1 - function was scheduled for execution |
| */ |
| int execute_in_process_context(work_func_t fn, struct execute_work *ew) |
| { |
| if (!in_interrupt()) { |
| fn(&ew->work); |
| return 0; |
| } |
| |
| INIT_WORK(&ew->work, fn); |
| schedule_work(&ew->work); |
| |
| return 1; |
| } |
| EXPORT_SYMBOL_GPL(execute_in_process_context); |
| |
| int keventd_up(void) |
| { |
| return keventd_wq != NULL; |
| } |
| |
| int current_is_keventd(void) |
| { |
| struct cpu_workqueue_struct *cwq; |
| int cpu = raw_smp_processor_id(); /* preempt-safe: keventd is per-cpu */ |
| int ret = 0; |
| |
| BUG_ON(!keventd_wq); |
| |
| cwq = per_cpu_ptr(keventd_wq->cpu_wq, cpu); |
| if (current == cwq->thread) |
| ret = 1; |
| |
| return ret; |
| |
| } |
| |
| 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 sched_param param = { .sched_priority = MAX_RT_PRIO-1 }; |
| struct workqueue_struct *wq = cwq->wq; |
| 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); |
| /* |
| * Nobody can add the work_struct to this cwq, |
| * if (caller is __create_workqueue) |
| * nobody should see this wq |
| * else // caller is CPU_UP_PREPARE |
| * cpu is not on cpu_online_map |
| * so we can abort safely. |
| */ |
| 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; |
| } |
| |
| static void start_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu) |
| { |
| struct task_struct *p = cwq->thread; |
| |
| if (p != NULL) { |
| if (cpu >= 0) |
| kthread_bind(p, cpu); |
| wake_up_process(p); |
| } |
| } |
| |
| 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; |
| int err = 0, cpu; |
| |
| wq = kzalloc(sizeof(*wq), GFP_KERNEL); |
| if (!wq) |
| return NULL; |
| |
| wq->cpu_wq = alloc_percpu(struct cpu_workqueue_struct); |
| if (!wq->cpu_wq) { |
| kfree(wq); |
| return NULL; |
| } |
| |
| 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) { |
| 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(); |
| } |
| |
| if (err) { |
| destroy_workqueue(wq); |
| wq = NULL; |
| } |
| return wq; |
| } |
| EXPORT_SYMBOL_GPL(__create_workqueue_key); |
| |
| static void cleanup_workqueue_thread(struct cpu_workqueue_struct *cwq) |
| { |
| /* |
| * 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_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. |
| */ |
| trace_workqueue_destruction(cwq->thread); |
| kthread_stop(cwq->thread); |
| cwq->thread = NULL; |
| } |
| |
| /** |
| * destroy_workqueue - safely terminate a workqueue |
| * @wq: target workqueue |
| * |
| * Safely destroy a workqueue. All work currently pending will be done first. |
| */ |
| void destroy_workqueue(struct workqueue_struct *wq) |
| { |
| const struct cpumask *cpu_map = wq_cpu_map(wq); |
| int cpu; |
| |
| cpu_maps_update_begin(); |
| spin_lock(&workqueue_lock); |
| list_del(&wq->list); |
| spin_unlock(&workqueue_lock); |
| |
| 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); |
| } |
| EXPORT_SYMBOL_GPL(destroy_workqueue); |
| |
| static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, |
| unsigned long action, |
| void *hcpu) |
| { |
| 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_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); |
| |
| switch (action) { |
| case CPU_UP_PREPARE: |
| if (!create_workqueue_thread(cwq, cpu)) |
| break; |
| 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); |
| break; |
| |
| case CPU_UP_CANCELED: |
| start_workqueue_thread(cwq, -1); |
| case CPU_POST_DEAD: |
| cleanup_workqueue_thread(cwq); |
| break; |
| } |
| } |
| |
| 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) |
| { |
| 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); |
| } |