* 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 workqueue_struct *wq;
struct task_struct *thread;
- int should_stop;
-
- int run_depth; /* Detect run_workqueue() recursion depth */
} ____cacheline_aligned;
/*
const char *name;
int singlethread;
int freezeable; /* Freeze threads during suspend */
+ int rt;
+#ifdef CONFIG_LOCKDEP
+ struct lockdep_map lockdep_map;
+#endif
+};
+
+#ifdef CONFIG_DEBUG_OBJECTS_WORK
+
+static struct debug_obj_descr work_debug_descr;
+
+/*
+ * fixup_init is called when:
+ * - an active object is initialized
+ */
+static int work_fixup_init(void *addr, enum debug_obj_state state)
+{
+ struct work_struct *work = addr;
+
+ switch (state) {
+ case ODEBUG_STATE_ACTIVE:
+ cancel_work_sync(work);
+ debug_object_init(work, &work_debug_descr);
+ return 1;
+ default:
+ return 0;
+ }
+}
+
+/*
+ * fixup_activate is called when:
+ * - an active object is activated
+ * - an unknown object is activated (might be a statically initialized object)
+ */
+static int work_fixup_activate(void *addr, enum debug_obj_state state)
+{
+ struct work_struct *work = addr;
+
+ switch (state) {
+
+ case ODEBUG_STATE_NOTAVAILABLE:
+ /*
+ * This is not really a fixup. The work struct was
+ * statically initialized. We just make sure that it
+ * is tracked in the object tracker.
+ */
+ if (test_bit(WORK_STRUCT_STATIC, work_data_bits(work))) {
+ debug_object_init(work, &work_debug_descr);
+ debug_object_activate(work, &work_debug_descr);
+ return 0;
+ }
+ WARN_ON_ONCE(1);
+ return 0;
+
+ case ODEBUG_STATE_ACTIVE:
+ WARN_ON(1);
+
+ default:
+ return 0;
+ }
+}
+
+/*
+ * fixup_free is called when:
+ * - an active object is freed
+ */
+static int work_fixup_free(void *addr, enum debug_obj_state state)
+{
+ struct work_struct *work = addr;
+
+ switch (state) {
+ case ODEBUG_STATE_ACTIVE:
+ cancel_work_sync(work);
+ debug_object_free(work, &work_debug_descr);
+ return 1;
+ default:
+ return 0;
+ }
+}
+
+static struct debug_obj_descr work_debug_descr = {
+ .name = "work_struct",
+ .fixup_init = work_fixup_init,
+ .fixup_activate = work_fixup_activate,
+ .fixup_free = work_fixup_free,
};
-/* All the per-cpu workqueues on the system, for hotplug cpu to add/remove
- threads to each one as cpus come/go. */
-static DEFINE_MUTEX(workqueue_mutex);
+static inline void debug_work_activate(struct work_struct *work)
+{
+ debug_object_activate(work, &work_debug_descr);
+}
+
+static inline void debug_work_deactivate(struct work_struct *work)
+{
+ debug_object_deactivate(work, &work_debug_descr);
+}
+
+void __init_work(struct work_struct *work, int onstack)
+{
+ if (onstack)
+ debug_object_init_on_stack(work, &work_debug_descr);
+ else
+ debug_object_init(work, &work_debug_descr);
+}
+EXPORT_SYMBOL_GPL(__init_work);
+
+void destroy_work_on_stack(struct work_struct *work)
+{
+ debug_object_free(work, &work_debug_descr);
+}
+EXPORT_SYMBOL_GPL(destroy_work_on_stack);
+
+#else
+static inline void debug_work_activate(struct work_struct *work) { }
+static inline void debug_work_deactivate(struct work_struct *work) { }
+#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 cpumask_t cpu_singlethread_map __read_mostly;
-/* optimization, we could use cpu_possible_map */
-static cpumask_t cpu_populated_map __read_mostly;
+static const struct cpumask *cpu_singlethread_map __read_mostly;
+/*
+ * _cpu_down() first removes CPU from cpu_online_map, then CPU_DEAD
+ * flushes cwq->worklist. This means that flush_workqueue/wait_on_work
+ * 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 cpumask_t *wq_cpu_map(struct workqueue_struct *wq)
+static const struct cpumask *wq_cpu_map(struct workqueue_struct *wq)
{
- return is_single_threaded(wq)
- ? &cpu_singlethread_map : &cpu_populated_map;
+ return is_wq_single_threaded(wq)
+ ? cpu_singlethread_map : cpu_populated_map;
}
static
struct cpu_workqueue_struct *wq_per_cpu(struct workqueue_struct *wq, int cpu)
{
- if (unlikely(is_single_threaded(wq)))
+ if (unlikely(is_wq_single_threaded(wq)))
cpu = singlethread_cpu;
return per_cpu_ptr(wq->cpu_wq, cpu);
}
atomic_long_set(&work->data, new);
}
+/*
+ * Clear WORK_STRUCT_PENDING and the workqueue on which it was queued.
+ */
+static inline void clear_wq_data(struct work_struct *work)
+{
+ unsigned long flags = *work_data_bits(work) &
+ (1UL << WORK_STRUCT_STATIC);
+ atomic_long_set(&work->data, flags);
+}
+
static inline
struct cpu_workqueue_struct *get_wq_data(struct work_struct *work)
{
}
static void insert_work(struct cpu_workqueue_struct *cwq,
- struct work_struct *work, int tail)
+ struct work_struct *work, struct list_head *head)
{
+ trace_workqueue_insertion(cwq->thread, work);
+
set_wq_data(work, cwq);
/*
* Ensure that we get the right work->data if we see the
* result of list_add() below, see try_to_grab_pending().
*/
smp_wmb();
- if (tail)
- list_add_tail(&work->entry, &cwq->worklist);
- else
- list_add(&work->entry, &cwq->worklist);
+ list_add_tail(&work->entry, head);
wake_up(&cwq->more_work);
}
-/* Preempt must be disabled. */
static void __queue_work(struct cpu_workqueue_struct *cwq,
struct work_struct *work)
{
unsigned long flags;
+ debug_work_activate(work);
spin_lock_irqsave(&cwq->lock, flags);
- insert_work(cwq, work, 1);
+ insert_work(cwq, work, &cwq->worklist);
spin_unlock_irqrestore(&cwq->lock, flags);
}
*
* Returns 0 if @work was already on a queue, non-zero otherwise.
*
- * We queue the work to the CPU it was submitted, but there is no
- * guarantee that it will be processed by that CPU.
+ * We queue the work to the CPU on which it was submitted, but if the CPU dies
+ * it can be processed by another CPU.
*/
-int fastcall queue_work(struct workqueue_struct *wq, struct work_struct *work)
+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, get_cpu()), work);
- put_cpu();
+ __queue_work(wq_per_cpu(wq, cpu), work);
ret = 1;
}
return ret;
}
-EXPORT_SYMBOL_GPL(queue_work);
+EXPORT_SYMBOL_GPL(queue_work_on);
-void delayed_work_timer_fn(unsigned long __data)
+static void delayed_work_timer_fn(unsigned long __data)
{
struct delayed_work *dwork = (struct delayed_work *)__data;
struct cpu_workqueue_struct *cwq = get_wq_data(&dwork->work);
*
* Returns 0 if @work was already on a queue, non-zero otherwise.
*/
-int fastcall queue_delayed_work(struct workqueue_struct *wq,
+int queue_delayed_work(struct workqueue_struct *wq,
struct delayed_work *dwork, unsigned long delay)
{
- timer_stats_timer_set_start_info(&dwork->timer);
if (delay == 0)
return queue_work(wq, &dwork->work);
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;
static void run_workqueue(struct cpu_workqueue_struct *cwq)
{
spin_lock_irq(&cwq->lock);
- cwq->run_depth++;
- if (cwq->run_depth > 3) {
- /* morton gets to eat his hat */
- printk("%s: recursion depth exceeded: %d\n",
- __FUNCTION__, cwq->run_depth);
- dump_stack();
- }
while (!list_empty(&cwq->worklist)) {
struct work_struct *work = list_entry(cwq->worklist.next,
struct work_struct, entry);
work_func_t f = work->func;
-
+#ifdef CONFIG_LOCKDEP
+ /*
+ * It is permissible to free the struct work_struct
+ * from inside the function that is called from it,
+ * this we need to take into account for lockdep too.
+ * To avoid bogus "held lock freed" warnings as well
+ * as problems when looking into work->lockdep_map,
+ * make a copy and use that here.
+ */
+ struct lockdep_map lockdep_map = work->lockdep_map;
+#endif
+ trace_workqueue_execution(cwq->thread, work);
+ debug_work_deactivate(work);
cwq->current_work = work;
list_del_init(cwq->worklist.next);
spin_unlock_irq(&cwq->lock);
BUG_ON(get_wq_data(work) != cwq);
work_clear_pending(work);
+ lock_map_acquire(&cwq->wq->lockdep_map);
+ lock_map_acquire(&lockdep_map);
f(work);
+ lock_map_release(&lockdep_map);
+ lock_map_release(&cwq->wq->lockdep_map);
if (unlikely(in_atomic() || lockdep_depth(current) > 0)) {
printk(KERN_ERR "BUG: workqueue leaked lock or atomic: "
"%s/0x%08x/%d\n",
current->comm, preempt_count(),
- current->pid);
+ task_pid_nr(current));
printk(KERN_ERR " last function: ");
print_symbol("%s\n", (unsigned long)f);
debug_show_held_locks(current);
spin_lock_irq(&cwq->lock);
cwq->current_work = NULL;
}
- cwq->run_depth--;
spin_unlock_irq(&cwq->lock);
}
-/*
- * 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;
-}
-
static int worker_thread(void *__cwq)
{
struct cpu_workqueue_struct *cwq = __cwq;
DEFINE_WAIT(wait);
- if (!cwq->wq->freezeable)
- current->flags |= PF_NOFREEZE;
-
- set_user_nice(current, -5);
+ if (cwq->wq->freezeable)
+ set_freezable();
for (;;) {
prepare_to_wait(&cwq->more_work, &wait, TASK_INTERRUPTIBLE);
- if (!freezing(current) && !cwq->should_stop
- && list_empty(&cwq->worklist))
+ if (!freezing(current) &&
+ !kthread_should_stop() &&
+ list_empty(&cwq->worklist))
schedule();
finish_wait(&cwq->more_work, &wait);
try_to_freeze();
- if (cwq_should_stop(cwq))
+ if (kthread_should_stop())
break;
run_workqueue(cwq);
}
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);
+ /*
+ * debugobject calls are safe here even with cwq->lock locked
+ * as we know for sure that this will not trigger any of the
+ * checks and call back into the fixup functions where we
+ * might deadlock.
+ */
+ INIT_WORK_ON_STACK(&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);
+ debug_work_activate(&barr->work);
+ 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);
+
+ 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);
+ if (active) {
+ wait_for_completion(&barr.done);
+ destroy_work_on_stack(&barr.work);
}
+
+ 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)
{
- const cpumask_t *cpu_map = wq_cpu_map(wq);
+ const struct cpumask *cpu_map = wq_cpu_map(wq);
int cpu;
might_sleep();
- for_each_cpu_mask(cpu, *cpu_map)
+ lock_map_acquire(&wq->lockdep_map);
+ lock_map_release(&wq->lockdep_map);
+ for_each_cpu(cpu, cpu_map)
flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, cpu));
}
EXPORT_SYMBOL_GPL(flush_workqueue);
+/**
+ * flush_work - block until a work_struct's callback has terminated
+ * @work: the work which is to be flushed
+ *
+ * Returns false if @work has already terminated.
+ *
+ * It is expected that, prior to calling flush_work(), the caller has
+ * arranged for the work to not be requeued, otherwise it doesn't make
+ * sense to use this function.
+ */
+int flush_work(struct work_struct *work)
+{
+ struct cpu_workqueue_struct *cwq;
+ struct list_head *prev;
+ struct wq_barrier barr;
+
+ might_sleep();
+ cwq = get_wq_data(work);
+ if (!cwq)
+ return 0;
+
+ lock_map_acquire(&cwq->wq->lockdep_map);
+ lock_map_release(&cwq->wq->lockdep_map);
+
+ prev = NULL;
+ spin_lock_irq(&cwq->lock);
+ if (!list_empty(&work->entry)) {
+ /*
+ * See the comment near try_to_grab_pending()->smp_rmb().
+ * If it was re-queued under us we are not going to wait.
+ */
+ smp_rmb();
+ if (unlikely(cwq != get_wq_data(work)))
+ goto out;
+ prev = &work->entry;
+ } else {
+ if (cwq->current_work != work)
+ goto out;
+ prev = &cwq->worklist;
+ }
+ insert_wq_barrier(cwq, &barr, prev->next);
+out:
+ spin_unlock_irq(&cwq->lock);
+ if (!prev)
+ return 0;
+
+ wait_for_completion(&barr.done);
+ destroy_work_on_stack(&barr.work);
+ return 1;
+}
+EXPORT_SYMBOL_GPL(flush_work);
+
/*
- * Upon a successful return, the caller "owns" WORK_STRUCT_PENDING bit,
+ * 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 = 0;
+ int ret = -1;
if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work)))
- return 1;
+ return 0;
/*
* The queueing is in progress, or it is already queued. Try to
*/
smp_rmb();
if (cwq == get_wq_data(work)) {
+ debug_work_deactivate(work);
list_del_init(&work->entry);
ret = 1;
}
spin_lock_irq(&cwq->lock);
if (unlikely(cwq->current_work == work)) {
- insert_wq_barrier(cwq, &barr, 0);
+ insert_wq_barrier(cwq, &barr, cwq->worklist.next);
running = 1;
}
spin_unlock_irq(&cwq->lock);
- if (unlikely(running))
+ if (unlikely(running)) {
wait_for_completion(&barr.done);
+ destroy_work_on_stack(&barr.work);
+ }
}
static void wait_on_work(struct work_struct *work)
{
struct cpu_workqueue_struct *cwq;
struct workqueue_struct *wq;
- const cpumask_t *cpu_map;
+ const struct cpumask *cpu_map;
int cpu;
might_sleep();
+ lock_map_acquire(&work->lockdep_map);
+ lock_map_release(&work->lockdep_map);
+
cwq = get_wq_data(work);
if (!cwq)
return;
wq = cwq->wq;
cpu_map = wq_cpu_map(wq);
- for_each_cpu_mask(cpu, *cpu_map)
+ for_each_cpu(cpu, cpu_map)
wait_on_cpu_work(per_cpu_ptr(wq->cpu_wq, cpu), work);
}
+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));
+
+ clear_wq_data(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.
* 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)
+int cancel_work_sync(struct work_struct *work)
{
- while (!try_to_grab_pending(work))
- cpu_relax();
- wait_on_work(work);
- work_clear_pending(work);
+ return __cancel_work_timer(work, NULL);
}
EXPORT_SYMBOL_GPL(cancel_work_sync);
/**
- * cancel_rearming_delayed_work - reliably kill off a delayed work.
+ * 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().
*/
-void cancel_rearming_delayed_work(struct delayed_work *dwork)
+int cancel_delayed_work_sync(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);
+ return __cancel_work_timer(&dwork->work, &dwork->timer);
}
-EXPORT_SYMBOL(cancel_rearming_delayed_work);
+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
*
- * 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);
/**
+ * flush_delayed_work - block until a dwork_struct's callback has terminated
+ * @dwork: the delayed work which is to be flushed
+ *
+ * Any timeout is cancelled, and any pending work is run immediately.
+ */
+void flush_delayed_work(struct delayed_work *dwork)
+{
+ if (del_timer_sync(&dwork->timer)) {
+ struct cpu_workqueue_struct *cwq;
+ cwq = wq_per_cpu(get_wq_data(&dwork->work)->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
* Returns zero on success.
* Returns -ve errno on failure.
*
- * Appears to be racy against CPU hotplug.
- *
* schedule_on_each_cpu() is very slow.
*/
int schedule_on_each_cpu(work_func_t func)
{
int cpu;
+ int orig = -1;
struct work_struct *works;
works = alloc_percpu(struct work_struct);
if (!works)
return -ENOMEM;
- preempt_disable(); /* CPU hotplug */
+ get_online_cpus();
+
+ /*
+ * When running in keventd don't schedule a work item on
+ * itself. Can just call directly because the work queue is
+ * already bound. This also is faster.
+ */
+ if (current_is_keventd())
+ orig = raw_smp_processor_id();
+
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);
+ if (cpu != orig)
+ schedule_work_on(cpu, work);
}
- preempt_enable();
- flush_workqueue(keventd_wq);
+ if (orig >= 0)
+ func(per_cpu_ptr(works, orig));
+
+ for_each_online_cpu(cpu)
+ flush_work(per_cpu_ptr(works, cpu));
+
+ put_online_cpus();
free_percpu(works);
return 0;
}
+/**
+ * flush_scheduled_work - ensure that any scheduled work has run to completion.
+ *
+ * Forces execution of the kernel-global workqueue and blocks until its
+ * completion.
+ *
+ * Think twice before calling this function! It's very easy to get into
+ * trouble if you don't take great care. Either of the following situations
+ * will lead to deadlock:
+ *
+ * One of the work items currently on the workqueue needs to acquire
+ * a lock held by your code or its caller.
+ *
+ * Your code is running in the context of a work routine.
+ *
+ * They will be detected by lockdep when they occur, but the first might not
+ * occur very often. It depends on what work items are on the workqueue and
+ * what locks they need, which you have no control over.
+ *
+ * In most situations flushing the entire workqueue is overkill; you merely
+ * need to know that a particular work item isn't queued and isn't running.
+ * In such cases you should use cancel_delayed_work_sync() or
+ * cancel_work_sync() instead.
+ */
void flush_scheduled_work(void)
{
flush_workqueue(keventd_wq);
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);
static int create_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu)
{
+ struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
struct workqueue_struct *wq = cwq->wq;
- const char *fmt = is_single_threaded(wq) ? "%s" : "%s/%d";
+ const char *fmt = is_wq_single_threaded(wq) ? "%s" : "%s/%d";
struct task_struct *p;
p = kthread_create(worker_thread, cwq, fmt, wq->name, cpu);
*/
if (IS_ERR(p))
return PTR_ERR(p);
-
+ if (cwq->wq->rt)
+ sched_setscheduler_nocheck(p, SCHED_FIFO, ¶m);
cwq->thread = p;
- cwq->should_stop = 0;
+
+ trace_workqueue_creation(cwq->thread, cpu);
return 0;
}
}
}
-struct workqueue_struct *__create_workqueue(const char *name,
- int singlethread, int freezeable)
+struct workqueue_struct *__create_workqueue_key(const char *name,
+ int singlethread,
+ int freezeable,
+ int rt,
+ struct lock_class_key *key,
+ const char *lock_name)
{
struct workqueue_struct *wq;
struct cpu_workqueue_struct *cwq;
}
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) {
err = create_workqueue_thread(cwq, singlethread_cpu);
start_workqueue_thread(cwq, -1);
} else {
- mutex_lock(&workqueue_mutex);
+ cpu_maps_update_begin();
+ /*
+ * We must place this wq on list even if the code below fails.
+ * cpu_down(cpu) can remove cpu from cpu_populated_map before
+ * destroy_workqueue() takes the lock, in that case we leak
+ * cwq[cpu]->thread.
+ */
+ spin_lock(&workqueue_lock);
list_add(&wq->list, &workqueues);
-
+ spin_unlock(&workqueue_lock);
+ /*
+ * We must initialize cwqs for each possible cpu even if we
+ * are going to call destroy_workqueue() finally. Otherwise
+ * cpu_up() can hit the uninitialized cwq once we drop the
+ * lock.
+ */
for_each_possible_cpu(cpu) {
cwq = init_cpu_workqueue(wq, cpu);
if (err || !cpu_online(cpu))
err = create_workqueue_thread(cwq, cpu);
start_workqueue_thread(cwq, cpu);
}
- mutex_unlock(&workqueue_mutex);
+ cpu_maps_update_done();
}
if (err) {
}
return wq;
}
-EXPORT_SYMBOL_GPL(__create_workqueue);
+EXPORT_SYMBOL_GPL(__create_workqueue_key);
-static void cleanup_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu)
+static void cleanup_workqueue_thread(struct cpu_workqueue_struct *cwq)
{
- 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_POST_DEAD,
+ * cpu_add_remove_lock protects cwq->thread.
+ */
+ if (cwq->thread == NULL)
+ return;
- if (alive) {
- wait_for_completion(&barr.done);
+ lock_map_acquire(&cwq->wq->lockdep_map);
+ lock_map_release(&cwq->wq->lockdep_map);
- 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);
- }
+ 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;
}
/**
*/
void destroy_workqueue(struct workqueue_struct *wq)
{
- const cpumask_t *cpu_map = wq_cpu_map(wq);
- struct cpu_workqueue_struct *cwq;
+ const struct cpumask *cpu_map = wq_cpu_map(wq);
int cpu;
- mutex_lock(&workqueue_mutex);
+ cpu_maps_update_begin();
+ spin_lock(&workqueue_lock);
list_del(&wq->list);
- mutex_unlock(&workqueue_mutex);
+ spin_unlock(&workqueue_lock);
- for_each_cpu_mask(cpu, *cpu_map) {
- cwq = per_cpu_ptr(wq->cpu_wq, cpu);
- cleanup_workqueue_thread(cwq, cpu);
- }
+ for_each_cpu(cpu, cpu_map)
+ cleanup_workqueue_thread(per_cpu_ptr(wq->cpu_wq, cpu));
+ cpu_maps_update_done();
free_percpu(wq->cpu_wq);
kfree(wq);
unsigned int cpu = (unsigned long)hcpu;
struct cpu_workqueue_struct *cwq;
struct workqueue_struct *wq;
+ int ret = NOTIFY_OK;
action &= ~CPU_TASKS_FROZEN;
switch (action) {
- case CPU_LOCK_ACQUIRE:
- mutex_lock(&workqueue_mutex);
- return NOTIFY_OK;
-
- case CPU_LOCK_RELEASE:
- mutex_unlock(&workqueue_mutex);
- return NOTIFY_OK;
-
case CPU_UP_PREPARE:
- cpu_set(cpu, cpu_populated_map);
+ cpumask_set_cpu(cpu, cpu_populated_map);
}
-
+undo:
list_for_each_entry(wq, &workqueues, list) {
cwq = per_cpu_ptr(wq->cpu_wq, cpu);
case CPU_UP_PREPARE:
if (!create_workqueue_thread(cwq, cpu))
break;
- printk(KERN_ERR "workqueue for %i failed\n", cpu);
- return NOTIFY_BAD;
+ printk(KERN_ERR "workqueue [%s] for %i failed\n",
+ wq->name, cpu);
+ action = CPU_UP_CANCELED;
+ ret = NOTIFY_BAD;
+ goto undo;
case CPU_ONLINE:
start_workqueue_thread(cwq, cpu);
case CPU_UP_CANCELED:
start_workqueue_thread(cwq, -1);
- case CPU_DEAD:
- cleanup_workqueue_thread(cwq, cpu);
+ case CPU_POST_DEAD:
+ cleanup_workqueue_thread(cwq);
break;
}
}
- return NOTIFY_OK;
+ switch (action) {
+ case CPU_UP_CANCELED:
+ case CPU_POST_DEAD:
+ cpumask_clear_cpu(cpu, cpu_populated_map);
+ }
+
+ return ret;
+}
+
+#ifdef CONFIG_SMP
+
+struct work_for_cpu {
+ struct completion completion;
+ long (*fn)(void *);
+ void *arg;
+ long ret;
+};
+
+static int do_work_for_cpu(void *_wfc)
+{
+ struct work_for_cpu *wfc = _wfc;
+ wfc->ret = wfc->fn(wfc->arg);
+ complete(&wfc->completion);
+ return 0;
+}
+
+/**
+ * work_on_cpu - run a function in user context on a particular cpu
+ * @cpu: the cpu to run on
+ * @fn: the function to run
+ * @arg: the function arg
+ *
+ * This will return the value @fn returns.
+ * It is up to the caller to ensure that the cpu doesn't go offline.
+ * The caller must not hold any locks which would prevent @fn from completing.
+ */
+long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
+{
+ struct task_struct *sub_thread;
+ struct work_for_cpu wfc = {
+ .completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion),
+ .fn = fn,
+ .arg = arg,
+ };
+
+ sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu");
+ if (IS_ERR(sub_thread))
+ return PTR_ERR(sub_thread);
+ kthread_bind(sub_thread, cpu);
+ wake_up_process(sub_thread);
+ wait_for_completion(&wfc.completion);
+ return wfc.ret;
}
+EXPORT_SYMBOL_GPL(work_on_cpu);
+#endif /* CONFIG_SMP */
void __init init_workqueues(void)
{
- cpu_populated_map = cpu_online_map;
- singlethread_cpu = first_cpu(cpu_possible_map);
- cpu_singlethread_map = cpumask_of_cpu(singlethread_cpu);
+ alloc_cpumask_var(&cpu_populated_map, GFP_KERNEL);
+
+ cpumask_copy(cpu_populated_map, cpu_online_mask);
+ singlethread_cpu = cpumask_first(cpu_possible_mask);
+ cpu_singlethread_map = cpumask_of(singlethread_cpu);
hotcpu_notifier(workqueue_cpu_callback, 0);
keventd_wq = create_workqueue("events");
BUG_ON(!keventd_wq);
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff