struct workqueue_struct *wq;
struct task_struct *thread;
- int should_stop;
int run_depth; /* Detect run_workqueue() recursion depth */
} ____cacheline_aligned;
static int singlethread_cpu __read_mostly;
static cpumask_t cpu_singlethread_map __read_mostly;
-/* optimization, we could use cpu_possible_map */
+/*
+ * _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. */
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;
+ if (cwq->wq->freezeable)
+ set_freezable();
set_user_nice(current, -5);
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);
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;
}
/**
EXPORT_SYMBOL_GPL(flush_workqueue);
/*
- * 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
wait_on_cpu_work(per_cpu_ptr(wq->cpu_wq, cpu), work);
}
+static int __cancel_work_timer(struct work_struct *work,
+ struct timer_list* timer)
+{
+ int ret;
+
+ do {
+ ret = (timer && likely(del_timer(timer)));
+ if (!ret)
+ ret = try_to_grab_pending(work);
+ wait_on_work(work);
+ } while (unlikely(ret < 0));
+
+ work_clear_pending(work);
+ return ret;
+}
+
/**
* cancel_work_sync - block until a work_struct's callback has terminated
* @work: the work which is to be flushed
*
+ * Returns true if @work was pending.
+ *
* cancel_work_sync() will cancel the work if it is queued. If the work's
* callback appears to be running, cancel_work_sync() will block until it
* has completed.
* 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;
return PTR_ERR(p);
cwq->thread = p;
- cwq->should_stop = 0;
return 0;
}
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);
-
- if (alive) {
- wait_for_completion(&barr.done);
+ /*
+ * Our caller is either destroy_workqueue() or CPU_DEAD,
+ * workqueue_mutex protects cwq->thread
+ */
+ if (cwq->thread == NULL)
+ return;
- 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_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.
+ */
+ kthread_stop(cwq->thread);
+ cwq->thread = NULL;
}
/**
git.openpandora.org / pandora-kernel.git / blobdiff