* Derived from the taskqueue/keventd code by:
*
* David Woodhouse <dwmw2@infradead.org>
- * Andrew Morton <andrewm@uow.edu.au>
+ * Andrew Morton
* Kai Petzke <wpp@marie.physik.tu-berlin.de>
* Theodore Ts'o <tytso@mit.edu>
*
- * Made to use alloc_percpu by Christoph Lameter <clameter@sgi.com>.
+ * Made to use alloc_percpu by Christoph Lameter.
*/
#include <linux/module.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
struct list_head worklist;
wait_queue_head_t more_work;
+ struct work_struct *current_work;
struct workqueue_struct *wq;
struct task_struct *thread;
- struct work_struct *current_work;
-
- 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 */
+ 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 long migrate_sequence __read_mostly;
-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;
+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_single_threaded(struct workqueue_struct *wq)
+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)
{
- return list_empty(&wq->list);
+ 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, 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, struct list_head *head)
{
- int ret = 0;
- unsigned long flags;
+ trace_workqueue_insertion(cwq->thread, work);
- 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;
- cwq->current_work = work;
- list_del_init(&work->entry);
- spin_unlock_irqrestore(&cwq->lock, flags);
+ smp_wmb();
+ list_add_tail(&work->entry, head);
+ wake_up(&cwq->more_work);
+}
- if (!test_bit(WORK_STRUCT_NOAUTOREL, work_data_bits(work)))
- work_release(work);
- f(work);
+static void __queue_work(struct cpu_workqueue_struct *cwq,
+ struct work_struct *work)
+{
+ unsigned long flags;
- spin_lock_irqsave(&cwq->lock, flags);
- cwq->current_work = NULL;
- ret = 1;
- }
+ spin_lock_irqsave(&cwq->lock, flags);
+ insert_work(cwq, work, &cwq->worklist);
spin_unlock_irqrestore(&cwq->lock, flags);
- return ret;
}
/**
- * run_scheduled_work - run scheduled work synchronously
- * @work: work to run
+ * queue_work - queue work on a workqueue
+ * @wq: workqueue to use
+ * @work: work to queue
*
- * 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.
+ * Returns 0 if @work was already on a queue, non-zero otherwise.
*
- * 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!
+ * 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 fastcall run_scheduled_work(struct work_struct *work)
+int queue_work(struct workqueue_struct *wq, 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);
- if (tail)
- list_add_tail(&work->entry, &cwq->worklist);
- else
- list_add(&work->entry, &cwq->worklist);
- wake_up(&cwq->more_work);
-}
+ int ret;
-/* Preempt must be disabled. */
-static void __queue_work(struct cpu_workqueue_struct *cwq,
- struct work_struct *work)
-{
- unsigned long flags;
+ ret = queue_work_on(get_cpu(), wq, work);
+ put_cpu();
- spin_lock_irqsave(&cwq->lock, flags);
- insert_work(cwq, work, 1);
- spin_unlock_irqrestore(&cwq->lock, flags);
+ return ret;
}
+EXPORT_SYMBOL_GPL(queue_work);
/**
- * queue_work - queue work on a workqueue
+ * 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 the CPU it was submitted, but there is no
- * guarantee that it will be processed by that CPU.
+ * 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, 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, cpu), work);
ret = 1;
}
- put_cpu();
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 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);
}
/**
*
* 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)
{
- int ret = 0;
- struct timer_list *timer = &dwork->timer;
- struct work_struct *work = &dwork->work;
-
- timer_stats_timer_set_start_info(timer);
if (delay == 0)
- return queue_work(wq, work);
-
- if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) {
- BUG_ON(timer_pending(timer));
- BUG_ON(!list_empty(&work->entry));
+ return queue_work(wq, &dwork->work);
- /* 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);
+ 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;
- 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);
- 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();
- }
+ 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_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);
+ 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);
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);
+ 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;
-
- if (!cwq->wq->freezeable)
- current->flags |= PF_NOFREEZE;
+ DEFINE_WAIT(wait);
- set_user_nice(current, -5);
+ if (cwq->wq->freezeable)
+ set_freezable();
- /* 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 (;;) {
+ 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);
- set_current_state(TASK_INTERRUPTIBLE);
- while (!kthread_should_stop()) {
- if (cwq->wq->freezeable)
- try_to_freeze();
+ try_to_freeze();
- 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 (kthread_should_stop())
+ break;
- 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 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 void flush_cpu_workqueue(struct cpu_workqueue_struct *cwq)
+static int flush_cpu_workqueue(struct cpu_workqueue_struct *cwq)
{
- if (cwq->thread == current) {
- /*
- * Probably keventd trying to flush its own queue. So simply run
- * it by hand rather than deadlocking.
- */
- run_workqueue(cwq);
- } else {
- struct wq_barrier barr;
- int active = 0;
+ int active = 0;
+ struct wq_barrier barr;
- 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;
}
/**
* 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)
{
- if (is_single_threaded(wq)) {
- /* Always use first cpu's area. */
- flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, singlethread_cpu));
- } else {
- long sequence;
- int cpu;
-again:
- sequence = migrate_sequence;
-
- for_each_possible_cpu(cpu)
- flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, cpu));
+ const struct cpumask *cpu_map = wq_cpu_map(wq);
+ int cpu;
- if (unlikely(sequence != migrate_sequence))
- goto again;
- }
+ 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);
-static void wait_on_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, 0);
- running = 1;
- }
- spin_unlock_irq(&cwq->lock);
-
- if (unlikely(running)) {
- mutex_unlock(&workqueue_mutex);
- wait_for_completion(&barr.done);
- mutex_lock(&workqueue_mutex);
- }
-}
-
/**
* 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.
+ * Returns false if @work has already terminated.
*
- * 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.
+ * 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.
*/
-void flush_work(struct workqueue_struct *wq, struct work_struct *work)
+int flush_work(struct work_struct *work)
{
struct cpu_workqueue_struct *cwq;
+ struct list_head *prev;
+ struct wq_barrier barr;
- mutex_lock(&workqueue_mutex);
+ might_sleep();
cwq = get_wq_data(work);
- /* Was it ever queued ? */
if (!cwq)
- goto out;
+ return 0;
- /*
- * This work can't be re-queued, and the lock above protects us
- * from take_over_work(), 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);
+ lock_map_acquire(&cwq->wq->lockdep_map);
+ lock_map_release(&cwq->wq->lockdep_map);
- if (is_single_threaded(wq)) {
- /* Always use first cpu's area. */
- wait_on_work(per_cpu_ptr(wq->cpu_wq, singlethread_cpu), work);
+ 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 {
- int cpu;
-
- for_each_online_cpu(cpu)
- wait_on_work(per_cpu_ptr(wq->cpu_wq, cpu), work);
+ if (cwq->current_work != work)
+ goto out;
+ prev = &cwq->worklist;
}
+ insert_wq_barrier(cwq, &barr, prev->next);
out:
- mutex_unlock(&workqueue_mutex);
+ spin_unlock_irq(&cwq->lock);
+ if (!prev)
+ return 0;
+
+ wait_for_completion(&barr.done);
+ return 1;
}
EXPORT_SYMBOL_GPL(flush_work);
-static void init_cpu_workqueue(struct workqueue_struct *wq, int cpu)
+/*
+ * 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 = per_cpu_ptr(wq->cpu_wq, cpu);
+ struct cpu_workqueue_struct *cwq;
+ int ret = -1;
- cwq->wq = wq;
- spin_lock_init(&cwq->lock);
- INIT_LIST_HEAD(&cwq->worklist);
- init_waitqueue_head(&cwq->more_work);
+ 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 struct task_struct *create_workqueue_thread(struct workqueue_struct *wq,
- int cpu)
+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;
- 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;
+ 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);
}
-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;
-
- wq = kzalloc(sizeof(*wq), GFP_KERNEL);
- if (!wq)
- return NULL;
+ const struct cpumask *cpu_map;
+ int cpu;
- wq->cpu_wq = alloc_percpu(struct cpu_workqueue_struct);
- if (!wq->cpu_wq) {
- kfree(wq);
- return NULL;
- }
+ might_sleep();
- wq->name = name;
- wq->freezeable = freezeable;
+ lock_map_acquire(&work->lockdep_map);
+ lock_map_release(&work->lockdep_map);
- mutex_lock(&workqueue_mutex);
- if (singlethread) {
- INIT_LIST_HEAD(&wq->list);
- init_cpu_workqueue(wq, singlethread_cpu);
- p = create_workqueue_thread(wq, singlethread_cpu);
- if (!p)
- destroy = 1;
- else
- wake_up_process(p);
- } else {
- list_add(&wq->list, &workqueues);
- for_each_possible_cpu(cpu) {
- init_cpu_workqueue(wq, cpu);
- if (!cpu_online(cpu))
- continue;
+ cwq = get_wq_data(work);
+ if (!cwq)
+ return;
- p = create_workqueue_thread(wq, cpu);
- 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(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)
+static int __cancel_work_timer(struct work_struct *work,
+ struct timer_list* timer)
{
- struct cpu_workqueue_struct *cwq = per_cpu_ptr(wq->cpu_wq, cpu);
+ int ret;
- if (cwq->thread) {
- kthread_stop(cwq->thread);
- cwq->thread = NULL;
- }
+ 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;
}
/**
- * destroy_workqueue - safely terminate a workqueue
- * @wq: target workqueue
+ * cancel_work_sync - block until a work_struct's callback has terminated
+ * @work: the work which is to be flushed
*
- * Safely destroy a workqueue. All work currently pending will be done first.
+ * 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.
*/
-void destroy_workqueue(struct workqueue_struct *wq)
+int cancel_work_sync(struct work_struct *work)
{
- int cpu;
-
- flush_workqueue(wq);
+ return __cancel_work_timer(work, NULL);
+}
+EXPORT_SYMBOL_GPL(cancel_work_sync);
- /* 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);
+/**
+ * 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_GPL(destroy_workqueue);
+EXPORT_SYMBOL(cancel_delayed_work_sync);
-static struct workqueue_struct *keventd_wq;
+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
* 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);
* 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)
if (!works)
return -ENOMEM;
- preempt_disable(); /* CPU hotplug */
+ get_online_cpus();
for_each_online_cpu(cpu) {
struct work_struct *work = per_cpu_ptr(works, cpu);
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)
+ flush_work(per_cpu_ptr(works, cpu));
+ put_online_cpus();
free_percpu(works);
return 0;
}
}
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
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);
}
-/* 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);
- migrate_sequence++;
-
- 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);
+ 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);
}
- 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_key(const char *name,
+ int singlethread,
+ int freezeable,
+ int rt,
+ struct lock_class_key *key,
+ const char *lock_name)
{
- 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)) {
- printk("workqueue for %i failed\n", hotcpu);
- return NOTIFY_BAD;
- }
+ 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);
}
- break;
+ 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);
- case CPU_ONLINE:
- /* Kick off worker threads. */
- list_for_each_entry(wq, &workqueues, list) {
- struct cpu_workqueue_struct *cwq;
+ 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;
+}
- cwq = per_cpu_ptr(wq->cpu_wq, hotcpu);
- kthread_bind(cwq->thread, hotcpu);
- wake_up_process(cwq->thread);
+/**
+ * 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;
}
- mutex_unlock(&workqueue_mutex);
- break;
+ }
+ switch (action) {
case CPU_UP_CANCELED:
- list_for_each_entry(wq, &workqueues, list) {
- if (!per_cpu_ptr(wq->cpu_wq, hotcpu)->thread)
- 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);
- }
- mutex_unlock(&workqueue_mutex);
- break;
-
- case CPU_DOWN_PREPARE:
- mutex_lock(&workqueue_mutex);
- break;
-
- case CPU_DOWN_FAILED:
- mutex_unlock(&workqueue_mutex);
- break;
-
- 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_POST_DEAD:
+ cpumask_clear_cpu(cpu, cpu_populated_map);
}
- return NOTIFY_OK;
+ return ret;
}
-void init_workqueues(void)
+#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)
{
- singlethread_cpu = first_cpu(cpu_possible_map);
+ 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);
}
-