struct workqueue_struct *wq;
struct task_struct *thread;
- int should_stop;
int run_depth; /* Detect run_workqueue() recursion depth */
} ____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 */
};
static LIST_HEAD(workqueues);
static int singlethread_cpu __read_mostly;
-/* optimization, we could use cpu_possible_map */
+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)
-{
- int ret = 0;
- unsigned long flags;
-
- spin_lock_irqsave(&cwq->lock, flags);
- /*
- * 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).
- */
- if (get_wq_data(work) == cwq
- && work_pending(work)
- && !list_empty(&work->entry)) {
- work_func_t f = work->func;
- cwq->current_work = work;
- 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->current_work = NULL;
- 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;
- }
-}
-EXPORT_SYMBOL(run_scheduled_work);
-
static void insert_work(struct cpu_workqueue_struct *cwq,
struct work_struct *work, int tail)
{
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
*/
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 */
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);
+ spin_lock_irq(&cwq->lock);
cwq->current_work = NULL;
}
cwq->run_depth--;
- spin_unlock_irqrestore(&cwq->lock, flags);
-}
-
-/*
- * NOTE: the caller must not touch *cwq if this func returns true
- */
-static int cwq_should_stop(struct cpu_workqueue_struct *cwq)
-{
- int should_stop = cwq->should_stop;
-
- if (unlikely(should_stop)) {
- spin_lock_irq(&cwq->lock);
- should_stop = cwq->should_stop && list_empty(&cwq->worklist);
- if (should_stop)
- cwq->thread = NULL;
- spin_unlock_irq(&cwq->lock);
- }
-
- return should_stop;
+ spin_unlock_irq(&cwq->lock);
}
static int worker_thread(void *__cwq)
{
struct cpu_workqueue_struct *cwq = __cwq;
DEFINE_WAIT(wait);
- struct k_sigaction sa;
- sigset_t blocked;
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();
-
- /* 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);
-
for (;;) {
- if (cwq->wq->freezeable)
- try_to_freeze();
-
prepare_to_wait(&cwq->more_work, &wait, TASK_INTERRUPTIBLE);
- if (!cwq->should_stop && list_empty(&cwq->worklist))
+ if (!freezing(current) &&
+ !kthread_should_stop() &&
+ list_empty(&cwq->worklist))
schedule();
finish_wait(&cwq->more_work, &wait);
- if (cwq_should_stop(cwq))
+ try_to_freeze();
+
+ if (kthread_should_stop())
break;
run_workqueue(cwq);
insert_work(cwq, &barr->work, tail);
}
-static void flush_cpu_workqueue(struct cpu_workqueue_struct *cwq)
+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;
+ active = 0;
spin_lock_irq(&cwq->lock);
if (!list_empty(&cwq->worklist) || cwq->current_work != NULL) {
insert_wq_barrier(cwq, &barr, 1);
if (active)
wait_for_completion(&barr.done);
}
+
+ return active;
}
/**
*/
void fastcall flush_workqueue(struct workqueue_struct *wq)
{
- if (is_single_threaded(wq))
- flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, singlethread_cpu));
- else {
- int cpu;
+ const cpumask_t *cpu_map = wq_cpu_map(wq);
+ int cpu;
- for_each_cpu_mask(cpu, cpu_populated_map)
- flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, 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);
-static void wait_on_work(struct cpu_workqueue_struct *cwq,
+/*
+ * 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;
+
+ 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;
+}
+
+static void wait_on_cpu_work(struct cpu_workqueue_struct *cwq,
struct work_struct *work)
{
struct wq_barrier barr;
wait_for_completion(&barr.done);
}
-/**
- * flush_work - block until a work_struct's callback has terminated
- * @wq: the workqueue on which the work is queued
- * @work: the work which is to be flushed
- *
- * flush_work() will attempt to cancel the work if it is queued. If the work's
- * callback appears to be running, flush_work() will block until it has
- * completed.
- *
- * flush_work() is designed to be used when the caller is tearing down data
- * structures which the callback function operates upon. It is expected that,
- * prior to calling flush_work(), the caller has arranged for the work to not
- * be requeued.
- */
-void flush_work(struct workqueue_struct *wq, struct work_struct *work)
+static void wait_on_work(struct work_struct *work)
{
struct cpu_workqueue_struct *cwq;
+ struct workqueue_struct *wq;
+ const cpumask_t *cpu_map;
+ int cpu;
+
+ might_sleep();
cwq = get_wq_data(work);
- /* Was it ever queued ? */
if (!cwq)
return;
- /*
- * This work can't be re-queued, no need to re-check that
- * get_wq_data() is still the same when we take cwq->lock.
- */
- spin_lock_irq(&cwq->lock);
- list_del_init(&work->entry);
- work_release(work);
- spin_unlock_irq(&cwq->lock);
+ wq = cwq->wq;
+ cpu_map = wq_cpu_map(wq);
- if (is_single_threaded(wq))
- wait_on_work(per_cpu_ptr(wq->cpu_wq, singlethread_cpu), work);
- else {
- int cpu;
+ for_each_cpu_mask(cpu, *cpu_map)
+ wait_on_cpu_work(per_cpu_ptr(wq->cpu_wq, cpu), work);
+}
- for_each_cpu_mask(cpu, cpu_populated_map)
- wait_on_work(per_cpu_ptr(wq->cpu_wq, cpu), work);
- }
+/**
+ * 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)
+{
+ while (!try_to_grab_pending(work))
+ cpu_relax();
+ wait_on_work(work);
+ work_clear_pending(work);
}
-EXPORT_SYMBOL_GPL(flush_work);
+EXPORT_SYMBOL_GPL(cancel_work_sync);
+/**
+ * cancel_rearming_delayed_work - reliably kill off a delayed work.
+ * @dwork: the delayed work struct
+ *
+ * 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 cancel_rearming_delayed_work(struct delayed_work *dwork)
+{
+ 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(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
}
EXPORT_SYMBOL(flush_scheduled_work);
-void flush_work_keventd(struct work_struct *work)
-{
- flush_work(keventd_wq, work);
-}
-EXPORT_SYMBOL(flush_work_keventd);
-
-/**
- * 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
return PTR_ERR(p);
cwq->thread = p;
- cwq->should_stop = 0;
- if (!is_single_threaded(wq))
- kthread_bind(p, cpu);
-
- if (is_single_threaded(wq) || cpu_online(cpu))
- wake_up_process(p);
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(const char *name,
int singlethread, int freezeable)
{
}
wq->name = name;
+ wq->singlethread = singlethread;
wq->freezeable = freezeable;
+ INIT_LIST_HEAD(&wq->list);
if (singlethread) {
- INIT_LIST_HEAD(&wq->list);
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);
if (err || !cpu_online(cpu))
continue;
err = create_workqueue_thread(cwq, cpu);
+ start_workqueue_thread(cwq, cpu);
}
mutex_unlock(&workqueue_mutex);
}
static void cleanup_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu)
{
- struct wq_barrier barr;
- int alive = 0;
-
- spin_lock_irq(&cwq->lock);
- if (cwq->thread != NULL) {
- insert_wq_barrier(cwq, &barr, 1);
- cwq->should_stop = 1;
- alive = 1;
- }
- spin_unlock_irq(&cwq->lock);
+ /*
+ * Our caller is either destroy_workqueue() or CPU_DEAD,
+ * workqueue_mutex protects cwq->thread
+ */
+ if (cwq->thread == NULL)
+ return;
- if (alive) {
- wait_for_completion(&barr.done);
+ /*
+ * 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))
+ ;
- while (unlikely(cwq->thread != NULL))
- cpu_relax();
- /*
- * Wait until cwq->thread unlocks cwq->lock,
- * it won't touch *cwq after that.
- */
- smp_rmb();
- spin_unlock_wait(&cwq->lock);
- }
+ kthread_stop(cwq->thread);
+ cwq->thread = NULL;
}
/**
*/
void destroy_workqueue(struct workqueue_struct *wq)
{
+ const cpumask_t *cpu_map = wq_cpu_map(wq);
struct cpu_workqueue_struct *cwq;
+ int cpu;
- if (is_single_threaded(wq)) {
- cwq = per_cpu_ptr(wq->cpu_wq, singlethread_cpu);
- cleanup_workqueue_thread(cwq, singlethread_cpu);
- } else {
- int cpu;
-
- mutex_lock(&workqueue_mutex);
- list_del(&wq->list);
- mutex_unlock(&workqueue_mutex);
+ mutex_lock(&workqueue_mutex);
+ list_del(&wq->list);
+ mutex_unlock(&workqueue_mutex);
- for_each_cpu_mask(cpu, cpu_populated_map) {
- cwq = per_cpu_ptr(wq->cpu_wq, cpu);
- cleanup_workqueue_thread(cwq, cpu);
- }
+ 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);
struct cpu_workqueue_struct *cwq;
struct workqueue_struct *wq;
+ action &= ~CPU_TASKS_FROZEN;
+
switch (action) {
case CPU_LOCK_ACQUIRE:
mutex_lock(&workqueue_mutex);
return NOTIFY_BAD;
case CPU_ONLINE:
- wake_up_process(cwq->thread);
+ start_workqueue_thread(cwq, cpu);
break;
case CPU_UP_CANCELED:
- if (cwq->thread)
- wake_up_process(cwq->thread);
+ 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