Merge branch 'for-3.1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

* 'for-3.1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: separate out drain_workqueue() from destroy_workqueue() workqueue: remove cancel_rearming_delayed_work[queue]()

Linus Torvalds committed 15 years ago

Commit 5a791ea2 parents 8209f53 9c5a2ba3 files · +55 −54Browse files

Showing the changes to kernel/workqueue.c (1 of 3 files). Show all

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kernel/workqueue.c+53−28

  * per-CPU workqueues:
  */
 struct workqueue_struct {
-	unsigned int		flags;		/* I: WQ_* flags */
+	unsigned int		flags;		/* W: WQ_* flags */
 	union {
 		struct cpu_workqueue_struct __percpu	*pcpu;
 		struct cpu_workqueue_struct		*single;
 	mayday_mask_t		mayday_mask;	/* cpus requesting rescue */
 	struct worker		*rescuer;	/* I: rescue worker */
+	int			nr_drainers;	/* W: drain in progress */
 	int			saved_max_active; /* W: saved cwq max_active */
 	const char		*name;		/* I: workqueue name */
 #ifdef CONFIG_LOCKDEP
 	debug_work_activate(work);
 	/* if dying, only works from the same workqueue are allowed */
-	if (unlikely(wq->flags & WQ_DYING) &&
+	if (unlikely(wq->flags & WQ_DRAINING) &&
 	    WARN_ON_ONCE(!is_chained_work(wq)))
 		return;
 }
 EXPORT_SYMBOL_GPL(flush_workqueue);
+/**
+ * drain_workqueue - drain a workqueue
+ * @wq: workqueue to drain
+ *
+ * Wait until the workqueue becomes empty.  While draining is in progress,
+ * only chain queueing is allowed.  IOW, only currently pending or running
+ * work items on @wq can queue further work items on it.  @wq is flushed
+ * repeatedly until it becomes empty.  The number of flushing is detemined
+ * by the depth of chaining and should be relatively short.  Whine if it
+ * takes too long.
+ */
+void drain_workqueue(struct workqueue_struct *wq)
+{
+	unsigned int flush_cnt = 0;
+	unsigned int cpu;
+	/*
+	 * __queue_work() needs to test whether there are drainers, is much
+	 * hotter than drain_workqueue() and already looks at @wq->flags.
+	 * Use WQ_DRAINING so that queue doesn't have to check nr_drainers.
+	 */
+	spin_lock(&workqueue_lock);
+	if (!wq->nr_drainers++)
+		wq->flags |= WQ_DRAINING;
+	spin_unlock(&workqueue_lock);
+reflush:
+	flush_workqueue(wq);
+	for_each_cwq_cpu(cpu, wq) {
+		struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
+		if (!cwq->nr_active && list_empty(&cwq->delayed_works))
+			continue;
+		if (++flush_cnt == 10 ||
+		    (flush_cnt % 100 == 0 && flush_cnt <= 1000))
+			pr_warning("workqueue %s: flush on destruction isn't complete after %u tries\n",
+				   wq->name, flush_cnt);
+		goto reflush;
+	}
+	spin_lock(&workqueue_lock);
+	if (!--wq->nr_drainers)
+		wq->flags &= ~WQ_DRAINING;
+	spin_unlock(&workqueue_lock);
+}
+EXPORT_SYMBOL_GPL(drain_workqueue);
 static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr,
 			     bool wait_executing)
 {
  */
 void destroy_workqueue(struct workqueue_struct *wq)
 {
-	unsigned int flush_cnt = 0;
 	unsigned int cpu;
-	/*
+	/* drain it before proceeding with destruction */
-	 * Mark @wq dying and drain all pending works.  Once WQ_DYING is
+	drain_workqueue(wq);
-	 * set, only chain queueing is allowed.  IOW, only currently
-	 * pending or running work items on @wq can queue further work
-	 * items on it.  @wq is flushed repeatedly until it becomes empty.
-	 * The number of flushing is detemined by the depth of chaining and
-	 * should be relatively short.  Whine if it takes too long.
-	 */
-	wq->flags |= WQ_DYING;
-reflush:
-	flush_workqueue(wq);
-	for_each_cwq_cpu(cpu, wq) {
-		struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
-		if (!cwq->nr_active && list_empty(&cwq->delayed_works))
-			continue;
-		if (++flush_cnt == 10 ||
-		    (flush_cnt % 100 == 0 && flush_cnt <= 1000))
-			printk(KERN_WARNING "workqueue %s: flush on "
-			       "destruction isn't complete after %u tries\n",
-			       wq->name, flush_cnt);
-		goto reflush;
-	}
 	/*
 	 * wq list is used to freeze wq, remove from list after