commit 609efa781b4a162e7c7ed75d748139ec4f628ba9
Author: Andriy Gapon <avg@icyb.net.ua>
Date:   Tue Nov 26 22:19:51 2013 +0200

    add taskqueue_drain_all

diff --git a/sys/kern/subr_taskqueue.c b/sys/kern/subr_taskqueue.c
index cbe80de..bfc941e 100644
--- a/sys/kern/subr_taskqueue.c
+++ b/sys/kern/subr_taskqueue.c
@@ -300,6 +300,15 @@ taskqueue_enqueue_timeout(struct taskqueue *queue,
 	return (res);
 }
 
+static void
+taskqueue_drain_running(struct taskqueue *queue)
+{
+
+	while (!TAILQ_EMPTY(&queue->tq_active))
+		TQ_SLEEP(queue, &queue->tq_active, &queue->tq_mutex,
+		    PWAIT, "-", 0);
+}
+
 void
 taskqueue_block(struct taskqueue *queue)
 {
@@ -350,6 +359,8 @@ taskqueue_run_locked(struct taskqueue *queue)
 		wakeup(task);
 	}
 	TAILQ_REMOVE(&queue->tq_active, &tb, tb_link);
+	if (TAILQ_EMPTY(&queue->tq_active))
+		wakeup(&queue->tq_active);
 }
 
 void
@@ -434,6 +445,25 @@ taskqueue_drain(struct taskqueue *queue, struct task *task)
 }
 
 void
+taskqueue_drain_all(struct taskqueue *queue)
+{
+	struct task *task;
+
+	if (!queue->tq_spin)
+		WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__);
+
+	TQ_LOCK(queue);
+	task = STAILQ_LAST(&queue->tq_queue, task, ta_link);
+	if (task != NULL)
+		while (task->ta_pending != 0)
+			TQ_SLEEP(queue, task, &queue->tq_mutex, PWAIT, "-", 0);
+	taskqueue_drain_running(queue);
+	KASSERT(STAILQ_EMPTY(&queue->tq_queue),
+	    ("taskqueue queue is not empty after draining"));
+	TQ_UNLOCK(queue);
+}
+
+void
 taskqueue_drain_timeout(struct taskqueue *queue,
     struct timeout_task *timeout_task)
 {
diff --git a/sys/sys/taskqueue.h b/sys/sys/taskqueue.h
index 7836262..326eb91 100644
--- a/sys/sys/taskqueue.h
+++ b/sys/sys/taskqueue.h
@@ -81,6 +81,7 @@ int	taskqueue_cancel_timeout(struct taskqueue *queue,
 void	taskqueue_drain(struct taskqueue *queue, struct task *task);
 void	taskqueue_drain_timeout(struct taskqueue *queue,
 	    struct timeout_task *timeout_task);
+void	taskqueue_drain_all(struct taskqueue *queue);
 void	taskqueue_free(struct taskqueue *queue);
 void	taskqueue_run(struct taskqueue *queue);
 void	taskqueue_block(struct taskqueue *queue);