/*
* The per-CPU workqueue (if single thread, we always use the first
* possible cpu).
- *
- * The sequence counters are for flush_scheduled_work(). It wants to wait
- * until all currently-scheduled works are completed, but it doesn't
- * want to be livelocked by new, incoming ones. So it waits until
- * remove_sequence is >= the insert_sequence which pertained when
- * flush_scheduled_work() was called.
*/
struct cpu_workqueue_struct {
spinlock_t lock;
- long remove_sequence; /* Least-recently added (next to run) */
- long insert_sequence; /* Next to add */
-
struct list_head worklist;
wait_queue_head_t more_work;
- wait_queue_head_t work_done;
+ struct work_struct *current_work;
struct workqueue_struct *wq;
struct task_struct *thread;
int run_depth; /* Detect run_workqueue() recursion depth */
-
- int freezeable; /* Freeze the thread during suspend */
} ____cacheline_aligned;
/*
*/
struct workqueue_struct {
struct cpu_workqueue_struct *cpu_wq;
+ struct list_head list;
const char *name;
- struct list_head list; /* Empty if single thread */
+ int singlethread;
+ int freezeable; /* Freeze threads during suspend */
};
/* All the per-cpu workqueues on the system, for hotplug cpu to add/remove
static DEFINE_MUTEX(workqueue_mutex);
static LIST_HEAD(workqueues);
-static int singlethread_cpu;
+static int singlethread_cpu __read_mostly;
+static cpumask_t 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_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)
{
- return list_empty(&wq->list);
+ return wq->singlethread;
+}
+
+static const cpumask_t *wq_cpu_map(struct workqueue_struct *wq)
+{
+ return is_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)))
+ 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, void *wq)
+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) wq | (1UL << WORK_STRUCT_PENDING);
+ 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 void *get_wq_data(struct work_struct *work)
+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 int __run_work(struct cpu_workqueue_struct *cwq, struct work_struct *work)
+static void insert_work(struct cpu_workqueue_struct *cwq,
+ struct work_struct *work, int tail)
{
- int ret = 0;
- unsigned long flags;
-
- spin_lock_irqsave(&cwq->lock, flags);
+ set_wq_data(work, cwq);
/*
- * We need to re-validate the work info after we've gotten
- * the cpu_workqueue lock. We can run the work now iff:
- *
- * - the wq_data still matches the cpu_workqueue_struct
- * - AND the work is still marked pending
- * - AND the work is still on a list (which will be this
- * workqueue_struct list)
- *
- * All these conditions are important, because we
- * need to protect against the work being run right
- * now on another CPU (all but the last one might be
- * true if it's currently running and has not been
- * released yet, for example).
+ * Ensure that we get the right work->data if we see the
+ * result of list_add() below, see try_to_grab_pending().
*/
- if (get_wq_data(work) == cwq
- && work_pending(work)
- && !list_empty(&work->entry)) {
- work_func_t f = work->func;
- list_del_init(&work->entry);
- spin_unlock_irqrestore(&cwq->lock, flags);
-
- if (!test_bit(WORK_STRUCT_NOAUTOREL, work_data_bits(work)))
- work_release(work);
- f(work);
-
- spin_lock_irqsave(&cwq->lock, flags);
- cwq->remove_sequence++;
- wake_up(&cwq->work_done);
- ret = 1;
- }
- spin_unlock_irqrestore(&cwq->lock, flags);
- return ret;
-}
-
-/**
- * run_scheduled_work - run scheduled work synchronously
- * @work: work to run
- *
- * This checks if the work was pending, and runs it
- * synchronously if so. It returns a boolean to indicate
- * whether it had any scheduled work to run or not.
- *
- * NOTE! This _only_ works for normal work_structs. You
- * CANNOT use this for delayed work, because the wq data
- * for delayed work will not point properly to the per-
- * CPU workqueue struct, but will change!
- */
-int fastcall run_scheduled_work(struct work_struct *work)
-{
- for (;;) {
- struct cpu_workqueue_struct *cwq;
-
- if (!work_pending(work))
- return 0;
- if (list_empty(&work->entry))
- return 0;
- /* NOTE! This depends intimately on __queue_work! */
- cwq = get_wq_data(work);
- if (!cwq)
- return 0;
- if (__run_work(cwq, work))
- return 1;
- }
+ smp_wmb();
+ if (tail)
+ list_add_tail(&work->entry, &cwq->worklist);
+ else
+ list_add(&work->entry, &cwq->worklist);
+ wake_up(&cwq->more_work);
}
-EXPORT_SYMBOL(run_scheduled_work);
/* Preempt must be disabled. */
static void __queue_work(struct cpu_workqueue_struct *cwq,
unsigned long flags;
spin_lock_irqsave(&cwq->lock, flags);
- set_wq_data(work, cwq);
- list_add_tail(&work->entry, &cwq->worklist);
- cwq->insert_sequence++;
- wake_up(&cwq->more_work);
+ insert_work(cwq, work, 1);
spin_unlock_irqrestore(&cwq->lock, flags);
}
*/
int fastcall queue_work(struct workqueue_struct *wq, struct work_struct *work)
{
- int ret = 0, cpu = get_cpu();
+ int ret = 0;
if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) {
- if (unlikely(is_single_threaded(wq)))
- cpu = singlethread_cpu;
BUG_ON(!list_empty(&work->entry));
- __queue_work(per_cpu_ptr(wq->cpu_wq, cpu), work);
+ __queue_work(wq_per_cpu(wq, get_cpu()), work);
+ put_cpu();
ret = 1;
}
- put_cpu();
return ret;
}
EXPORT_SYMBOL_GPL(queue_work);
void delayed_work_timer_fn(unsigned long __data)
{
struct delayed_work *dwork = (struct delayed_work *)__data;
- struct workqueue_struct *wq = get_wq_data(&dwork->work);
- int cpu = smp_processor_id();
-
- if (unlikely(is_single_threaded(wq)))
- cpu = singlethread_cpu;
+ struct cpu_workqueue_struct *cwq = get_wq_data(&dwork->work);
+ struct workqueue_struct *wq = cwq->wq;
- __queue_work(per_cpu_ptr(wq->cpu_wq, cpu), &dwork->work);
+ __queue_work(wq_per_cpu(wq, smp_processor_id()), &dwork->work);
}
/**
int fastcall queue_delayed_work(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;
-
- timer_stats_timer_set_start_info(timer);
+ timer_stats_timer_set_start_info(&dwork->timer);
if (delay == 0)
- return queue_work(wq, work);
+ return queue_work(wq, &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));
-
- /* This stores wq for the moment, for the timer_fn */
- set_wq_data(work, wq);
- timer->expires = jiffies + delay;
- timer->data = (unsigned long)dwork;
- timer->function = delayed_work_timer_fn;
- add_timer(timer);
- ret = 1;
- }
- return ret;
+ return queue_delayed_work_on(-1, wq, dwork, delay);
}
EXPORT_SYMBOL_GPL(queue_delayed_work);
BUG_ON(timer_pending(timer));
BUG_ON(!list_empty(&work->entry));
- /* This stores wq for the moment, for the timer_fn */
- set_wq_data(work, wq);
+ /* 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;
- add_timer_on(timer, cpu);
+
+ if (unlikely(cpu >= 0))
+ add_timer_on(timer, cpu);
+ else
+ add_timer(timer);
ret = 1;
}
return ret;
static void run_workqueue(struct cpu_workqueue_struct *cwq)
{
- unsigned long flags;
-
- /*
- * Keep taking off work from the queue until
- * done.
- */
- spin_lock_irqsave(&cwq->lock, flags);
+ spin_lock_irq(&cwq->lock);
cwq->run_depth++;
if (cwq->run_depth > 3) {
/* morton gets to eat his hat */
struct work_struct, entry);
work_func_t f = work->func;
+ cwq->current_work = work;
list_del_init(cwq->worklist.next);
- spin_unlock_irqrestore(&cwq->lock, flags);
+ spin_unlock_irq(&cwq->lock);
BUG_ON(get_wq_data(work) != cwq);
- if (!test_bit(WORK_STRUCT_NOAUTOREL, work_data_bits(work)))
- work_release(work);
+ work_clear_pending(work);
f(work);
if (unlikely(in_atomic() || lockdep_depth(current) > 0)) {
dump_stack();
}
- spin_lock_irqsave(&cwq->lock, flags);
- cwq->remove_sequence++;
- wake_up(&cwq->work_done);
+ spin_lock_irq(&cwq->lock);
+ cwq->current_work = NULL;
}
cwq->run_depth--;
- spin_unlock_irqrestore(&cwq->lock, flags);
+ spin_unlock_irq(&cwq->lock);
}
static int worker_thread(void *__cwq)
{
struct cpu_workqueue_struct *cwq = __cwq;
- DECLARE_WAITQUEUE(wait, current);
- struct k_sigaction sa;
- sigset_t blocked;
+ DEFINE_WAIT(wait);
- if (!cwq->freezeable)
+ if (!cwq->wq->freezeable)
current->flags |= PF_NOFREEZE;
set_user_nice(current, -5);
- /* Block and flush all signals */
- sigfillset(&blocked);
- sigprocmask(SIG_BLOCK, &blocked, NULL);
- flush_signals(current);
-
- /*
- * We inherited MPOL_INTERLEAVE from the booting kernel.
- * Set MPOL_DEFAULT to insure node local allocations.
- */
- numa_default_policy();
+ 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);
- /* SIG_IGN makes children autoreap: see do_notify_parent(). */
- sa.sa.sa_handler = SIG_IGN;
- sa.sa.sa_flags = 0;
- siginitset(&sa.sa.sa_mask, sigmask(SIGCHLD));
- do_sigaction(SIGCHLD, &sa, (struct k_sigaction *)0);
+ try_to_freeze();
- set_current_state(TASK_INTERRUPTIBLE);
- while (!kthread_should_stop()) {
- if (cwq->freezeable)
- try_to_freeze();
+ if (kthread_should_stop())
+ break;
- add_wait_queue(&cwq->more_work, &wait);
- if (list_empty(&cwq->worklist))
- schedule();
- else
- __set_current_state(TASK_RUNNING);
- remove_wait_queue(&cwq->more_work, &wait);
-
- if (!list_empty(&cwq->worklist))
- run_workqueue(cwq);
- set_current_state(TASK_INTERRUPTIBLE);
+ run_workqueue(cwq);
}
- __set_current_state(TASK_RUNNING);
+
return 0;
}
-static void flush_cpu_workqueue(struct cpu_workqueue_struct *cwq)
+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, int tail)
+{
+ 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);
+}
+
+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 {
- DEFINE_WAIT(wait);
- long sequence_needed;
+ struct wq_barrier barr;
+ active = 0;
spin_lock_irq(&cwq->lock);
- sequence_needed = cwq->insert_sequence;
-
- while (sequence_needed - cwq->remove_sequence > 0) {
- prepare_to_wait(&cwq->work_done, &wait,
- TASK_UNINTERRUPTIBLE);
- spin_unlock_irq(&cwq->lock);
- schedule();
- spin_lock_irq(&cwq->lock);
+ if (!list_empty(&cwq->worklist) || cwq->current_work != NULL) {
+ insert_wq_barrier(cwq, &barr, 1);
+ active = 1;
}
- finish_wait(&cwq->work_done, &wait);
spin_unlock_irq(&cwq->lock);
+
+ if (active)
+ wait_for_completion(&barr.done);
}
+
+ return active;
}
/**
* Forces execution of the workqueue and blocks until its completion.
* This is typically used in driver shutdown handlers.
*
- * This function will sample each workqueue's current insert_sequence number and
- * will sleep until the head sequence is greater than or equal to that. This
- * means that we sleep until all works which were queued on entry have been
- * handled, but we are not livelocked by new incoming ones.
+ * 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 fastcall flush_workqueue(struct workqueue_struct *wq)
{
+ const cpumask_t *cpu_map = wq_cpu_map(wq);
+ int cpu;
+
might_sleep();
+ for_each_cpu_mask(cpu, *cpu_map)
+ flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, cpu));
+}
+EXPORT_SYMBOL_GPL(flush_workqueue);
- if (is_single_threaded(wq)) {
- /* Always use first cpu's area. */
- flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, singlethread_cpu));
- } else {
- int cpu;
+/*
+ * Upon a successful return, 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 = 0;
- mutex_lock(&workqueue_mutex);
- for_each_online_cpu(cpu)
- flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, cpu));
- mutex_unlock(&workqueue_mutex);
+ if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work)))
+ return 1;
+
+ /*
+ * 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;
}
-EXPORT_SYMBOL_GPL(flush_workqueue);
-static struct task_struct *create_workqueue_thread(struct workqueue_struct *wq,
- int cpu, int freezeable)
+static void wait_on_cpu_work(struct cpu_workqueue_struct *cwq,
+ struct work_struct *work)
{
- struct cpu_workqueue_struct *cwq = per_cpu_ptr(wq->cpu_wq, cpu);
- struct task_struct *p;
+ struct wq_barrier barr;
+ int running = 0;
- spin_lock_init(&cwq->lock);
- cwq->wq = wq;
- cwq->thread = NULL;
- cwq->insert_sequence = 0;
- cwq->remove_sequence = 0;
- cwq->freezeable = freezeable;
- INIT_LIST_HEAD(&cwq->worklist);
- init_waitqueue_head(&cwq->more_work);
- init_waitqueue_head(&cwq->work_done);
+ spin_lock_irq(&cwq->lock);
+ if (unlikely(cwq->current_work == work)) {
+ insert_wq_barrier(cwq, &barr, 0);
+ running = 1;
+ }
+ spin_unlock_irq(&cwq->lock);
- if (is_single_threaded(wq))
- p = kthread_create(worker_thread, cwq, "%s", wq->name);
- else
- p = kthread_create(worker_thread, cwq, "%s/%d", wq->name, cpu);
- if (IS_ERR(p))
- return NULL;
- cwq->thread = p;
- return p;
+ if (unlikely(running))
+ wait_for_completion(&barr.done);
}
-struct workqueue_struct *__create_workqueue(const char *name,
- int singlethread, int freezeable)
+static void wait_on_work(struct work_struct *work)
{
- int cpu, destroy = 0;
+ struct cpu_workqueue_struct *cwq;
struct workqueue_struct *wq;
- struct task_struct *p;
+ const cpumask_t *cpu_map;
+ int cpu;
- wq = kzalloc(sizeof(*wq), GFP_KERNEL);
- if (!wq)
- return NULL;
+ might_sleep();
- wq->cpu_wq = alloc_percpu(struct cpu_workqueue_struct);
- if (!wq->cpu_wq) {
- kfree(wq);
- return NULL;
- }
+ cwq = get_wq_data(work);
+ if (!cwq)
+ return;
- wq->name = name;
- mutex_lock(&workqueue_mutex);
- if (singlethread) {
- INIT_LIST_HEAD(&wq->list);
- p = create_workqueue_thread(wq, singlethread_cpu, freezeable);
- if (!p)
- destroy = 1;
- else
- wake_up_process(p);
- } else {
- list_add(&wq->list, &workqueues);
- for_each_online_cpu(cpu) {
- p = create_workqueue_thread(wq, cpu, freezeable);
- if (p) {
- kthread_bind(p, cpu);
- wake_up_process(p);
- } else
- destroy = 1;
- }
- }
- mutex_unlock(&workqueue_mutex);
+ wq = cwq->wq;
+ cpu_map = wq_cpu_map(wq);
- /*
- * Was there any error during startup? If yes then clean up:
- */
- if (destroy) {
- destroy_workqueue(wq);
- wq = NULL;
- }
- return wq;
+ for_each_cpu_mask(cpu, *cpu_map)
+ wait_on_cpu_work(per_cpu_ptr(wq->cpu_wq, cpu), work);
}
-EXPORT_SYMBOL_GPL(__create_workqueue);
-static void cleanup_workqueue_thread(struct workqueue_struct *wq, int cpu)
+/**
+ * cancel_work_sync - block until a work_struct's callback has terminated
+ * @work: the work which is to be flushed
+ *
+ * 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.
+ */
+void cancel_work_sync(struct work_struct *work)
{
- struct cpu_workqueue_struct *cwq;
- unsigned long flags;
- struct task_struct *p;
-
- cwq = per_cpu_ptr(wq->cpu_wq, cpu);
- spin_lock_irqsave(&cwq->lock, flags);
- p = cwq->thread;
- cwq->thread = NULL;
- spin_unlock_irqrestore(&cwq->lock, flags);
- if (p)
- kthread_stop(p);
+ while (!try_to_grab_pending(work))
+ cpu_relax();
+ wait_on_work(work);
+ work_clear_pending(work);
}
+EXPORT_SYMBOL_GPL(cancel_work_sync);
/**
- * destroy_workqueue - safely terminate a workqueue
- * @wq: target workqueue
+ * cancel_rearming_delayed_work - reliably kill off a delayed work.
+ * @dwork: the delayed work struct
*
- * Safely destroy a workqueue. All work currently pending will be done first.
+ * 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().
*/
-void destroy_workqueue(struct workqueue_struct *wq)
+void cancel_rearming_delayed_work(struct delayed_work *dwork)
{
- int cpu;
-
- flush_workqueue(wq);
-
- /* We don't need the distraction of CPUs appearing and vanishing. */
- mutex_lock(&workqueue_mutex);
- if (is_single_threaded(wq))
- cleanup_workqueue_thread(wq, singlethread_cpu);
- else {
- for_each_online_cpu(cpu)
- cleanup_workqueue_thread(wq, cpu);
- list_del(&wq->list);
- }
- mutex_unlock(&workqueue_mutex);
- free_percpu(wq->cpu_wq);
- kfree(wq);
+ while (!del_timer(&dwork->timer) &&
+ !try_to_grab_pending(&dwork->work))
+ cpu_relax();
+ wait_on_work(&dwork->work);
+ work_clear_pending(&dwork->work);
}
-EXPORT_SYMBOL_GPL(destroy_workqueue);
+EXPORT_SYMBOL(cancel_rearming_delayed_work);
-static struct workqueue_struct *keventd_wq;
+static struct workqueue_struct *keventd_wq __read_mostly;
/**
* schedule_work - put work task in global workqueue
if (!works)
return -ENOMEM;
- mutex_lock(&workqueue_mutex);
+ preempt_disable(); /* CPU hotplug */
for_each_online_cpu(cpu) {
struct work_struct *work = per_cpu_ptr(works, cpu);
set_bit(WORK_STRUCT_PENDING, work_data_bits(work));
__queue_work(per_cpu_ptr(keventd_wq->cpu_wq, cpu), work);
}
- mutex_unlock(&workqueue_mutex);
+ preempt_enable();
flush_workqueue(keventd_wq);
free_percpu(works);
return 0;
}
EXPORT_SYMBOL(flush_scheduled_work);
-/**
- * cancel_rearming_delayed_workqueue - reliably kill off a delayed work whose handler rearms the delayed work.
- * @wq: the controlling workqueue structure
- * @dwork: the delayed work struct
- */
-void cancel_rearming_delayed_workqueue(struct workqueue_struct *wq,
- struct delayed_work *dwork)
-{
- while (!cancel_delayed_work(dwork))
- flush_workqueue(wq);
-}
-EXPORT_SYMBOL(cancel_rearming_delayed_workqueue);
-
-/**
- * cancel_rearming_delayed_work - reliably kill off a delayed keventd work whose handler rearms the delayed work.
- * @dwork: the delayed work struct
- */
-void cancel_rearming_delayed_work(struct delayed_work *dwork)
-{
- cancel_rearming_delayed_workqueue(keventd_wq, dwork);
-}
-EXPORT_SYMBOL(cancel_rearming_delayed_work);
-
/**
* execute_in_process_context - reliably execute the routine with user context
* @fn: the function to execute
}
-/* Take the work from this (downed) CPU. */
-static void take_over_work(struct workqueue_struct *wq, unsigned int cpu)
+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);
- struct list_head list;
- struct work_struct *work;
- spin_lock_irq(&cwq->lock);
- list_replace_init(&cwq->worklist, &list);
+ 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;
+ const char *fmt = is_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);
+
+ cwq->thread = p;
+
+ return 0;
+}
+
+static void start_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu)
+{
+ struct task_struct *p = cwq->thread;
- while (!list_empty(&list)) {
- printk("Taking work for %s\n", wq->name);
- work = list_entry(list.next,struct work_struct,entry);
- list_del(&work->entry);
- __queue_work(per_cpu_ptr(wq->cpu_wq, smp_processor_id()), work);
+ if (p != NULL) {
+ if (cpu >= 0)
+ kthread_bind(p, cpu);
+ wake_up_process(p);
}
- spin_unlock_irq(&cwq->lock);
}
-/* We're holding the cpucontrol mutex here */
-static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
- unsigned long action,
- void *hcpu)
+struct workqueue_struct *__create_workqueue(const char *name,
+ int singlethread, int freezeable)
{
- unsigned int hotcpu = (unsigned long)hcpu;
struct workqueue_struct *wq;
+ struct cpu_workqueue_struct *cwq;
+ int err = 0, cpu;
- switch (action) {
- case CPU_UP_PREPARE:
- mutex_lock(&workqueue_mutex);
- /* Create a new workqueue thread for it. */
- list_for_each_entry(wq, &workqueues, list) {
- if (!create_workqueue_thread(wq, hotcpu, 0)) {
- printk("workqueue for %i failed\n", hotcpu);
- return NOTIFY_BAD;
- }
- }
- break;
+ wq = kzalloc(sizeof(*wq), GFP_KERNEL);
+ if (!wq)
+ return NULL;
- case CPU_ONLINE:
- /* Kick off worker threads. */
- list_for_each_entry(wq, &workqueues, list) {
- struct cpu_workqueue_struct *cwq;
+ wq->cpu_wq = alloc_percpu(struct cpu_workqueue_struct);
+ if (!wq->cpu_wq) {
+ kfree(wq);
+ return NULL;
+ }
- cwq = per_cpu_ptr(wq->cpu_wq, hotcpu);
- kthread_bind(cwq->thread, hotcpu);
- wake_up_process(cwq->thread);
- }
- mutex_unlock(&workqueue_mutex);
- break;
+ wq->name = name;
+ wq->singlethread = singlethread;
+ wq->freezeable = freezeable;
+ INIT_LIST_HEAD(&wq->list);
- case CPU_UP_CANCELED:
- list_for_each_entry(wq, &workqueues, list) {
- if (!per_cpu_ptr(wq->cpu_wq, hotcpu)->thread)
+ if (singlethread) {
+ cwq = init_cpu_workqueue(wq, singlethread_cpu);
+ err = create_workqueue_thread(cwq, singlethread_cpu);
+ start_workqueue_thread(cwq, -1);
+ } else {
+ mutex_lock(&workqueue_mutex);
+ list_add(&wq->list, &workqueues);
+
+ for_each_possible_cpu(cpu) {
+ cwq = init_cpu_workqueue(wq, cpu);
+ if (err || !cpu_online(cpu))
continue;
- /* Unbind so it can run. */
- kthread_bind(per_cpu_ptr(wq->cpu_wq, hotcpu)->thread,
- any_online_cpu(cpu_online_map));
- cleanup_workqueue_thread(wq, hotcpu);
+ err = create_workqueue_thread(cwq, cpu);
+ start_workqueue_thread(cwq, cpu);
}
mutex_unlock(&workqueue_mutex);
- break;
+ }
- case CPU_DOWN_PREPARE:
+ if (err) {
+ destroy_workqueue(wq);
+ wq = NULL;
+ }
+ return wq;
+}
+EXPORT_SYMBOL_GPL(__create_workqueue);
+
+static void cleanup_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu)
+{
+ /*
+ * Our caller is either destroy_workqueue() or CPU_DEAD,
+ * workqueue_mutex protects cwq->thread
+ */
+ if (cwq->thread == NULL)
+ return;
+
+ /*
+ * If the caller is CPU_DEAD the single flush_cpu_workqueue()
+ * is not enough, a concurrent flush_workqueue() can insert a
+ * barrier after us.
+ * 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))
+ ;
+
+ 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 cpumask_t *cpu_map = wq_cpu_map(wq);
+ struct cpu_workqueue_struct *cwq;
+ int cpu;
+
+ mutex_lock(&workqueue_mutex);
+ list_del(&wq->list);
+ mutex_unlock(&workqueue_mutex);
+
+ for_each_cpu_mask(cpu, *cpu_map) {
+ cwq = per_cpu_ptr(wq->cpu_wq, cpu);
+ cleanup_workqueue_thread(cwq, cpu);
+ }
+
+ 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;
+
+ action &= ~CPU_TASKS_FROZEN;
+
+ switch (action) {
+ case CPU_LOCK_ACQUIRE:
mutex_lock(&workqueue_mutex);
- break;
+ return NOTIFY_OK;
- case CPU_DOWN_FAILED:
+ case CPU_LOCK_RELEASE:
mutex_unlock(&workqueue_mutex);
- break;
+ return NOTIFY_OK;
- case CPU_DEAD:
- list_for_each_entry(wq, &workqueues, list)
- cleanup_workqueue_thread(wq, hotcpu);
- list_for_each_entry(wq, &workqueues, list)
- take_over_work(wq, hotcpu);
- mutex_unlock(&workqueue_mutex);
- break;
+ case CPU_UP_PREPARE:
+ cpu_set(cpu, cpu_populated_map);
+ }
+
+ 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 for %i failed\n", cpu);
+ return NOTIFY_BAD;
+
+ case CPU_ONLINE:
+ start_workqueue_thread(cwq, cpu);
+ break;
+
+ case CPU_UP_CANCELED:
+ start_workqueue_thread(cwq, -1);
+ case CPU_DEAD:
+ cleanup_workqueue_thread(cwq, cpu);
+ break;
+ }
}
return NOTIFY_OK;
}
-void init_workqueues(void)
+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);
hotcpu_notifier(workqueue_cpu_callback, 0);
keventd_wq = create_workqueue("events");
BUG_ON(!keventd_wq);
}
-
git.samba.org / sfrench / cifs-2.6.git / blobdiff