Merge branch 'for-linus'

sound/core/timer.c

diff --git a/sound/core/timer.c b/sound/core/timer.c
index 13d7378..5bc217a 100644
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -489,10 +489,20 @@ static void snd_timer_close_locked(struct snd_timer_instance *timeri,
 	snd_timer_stop(timeri);
 
 	if (timer) {
+		struct snd_timer_instance *slave;
+		bool busy;
+
 		timer->num_instances--;
-		/* wait, until the active callback is finished */
+		/* unqueue then drain the slaves' callbacks before remove_slave_links() severs them */
 		spin_lock_irq(&timer->lock);
-		while (timeri->flags & SNDRV_TIMER_IFLG_CALLBACK) {
+		list_for_each_entry(slave, &timeri->slave_list_head, open_list)
+			list_del_init(&slave->ack_list);
+		for (;;) {
+			busy = timeri->flags & SNDRV_TIMER_IFLG_CALLBACK;
+			list_for_each_entry(slave, &timeri->slave_list_head, open_list)
+				busy |= slave->flags & SNDRV_TIMER_IFLG_CALLBACK;
+			if (!busy)
+				break;
 			spin_unlock_irq(&timer->lock);
 			udelay(10);
 			spin_lock_irq(&timer->lock);
@@ -927,12 +937,15 @@ void snd_timer_interrupt(struct snd_timer * timer, unsigned long ticks_left)
 			ack_list_head = &timer->ack_list_head;
 		else
 			ack_list_head = &timer->sack_list_head;
-		if (list_empty(&ti->ack_list))
+		/* don't requeue an instance whose callback is still running */
+		if (list_empty(&ti->ack_list) &&
+		    !(ti->flags & SNDRV_TIMER_IFLG_CALLBACK))
 			list_add_tail(&ti->ack_list, ack_list_head);
 		list_for_each_entry(ts, &ti->slave_active_head, active_list) {
 			ts->pticks = ti->pticks;
 			ts->resolution = resolution;
-			if (list_empty(&ts->ack_list))
+			if (list_empty(&ts->ack_list) &&
+			    !(ts->flags & SNDRV_TIMER_IFLG_CALLBACK))
 				list_add_tail(&ts->ack_list, ack_list_head);
 		}
 	}