[PATCH] cfq-iosched: fix bug in timer handling for the idle class

There's a small window from when the timer is entered and we grab the queue lock, where cfq_set_active_queue() could be rearming the timer for us. Seen in the wild on a 12-way ppc box. Fix this by just using mod_timer(), which will do the right thing for us. Signed-off-by: Jens Axboe <[email protected]>
rtvt123 · Jun 1, 2006 · ae818a3 · ae818a3
1 parent 25776e3
commit ae818a3
Showing 1 changed file with 3 additions and 4 deletions.
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
@@ -2193,10 +2193,9 @@ static void cfq_idle_class_timer(unsigned long data)
 	 * race with a non-idle queue, reset timer
 	 */
 	end = cfqd->last_end_request + CFQ_IDLE_GRACE;
-	if (!time_after_eq(jiffies, end)) {
-		cfqd->idle_class_timer.expires = end;
-		add_timer(&cfqd->idle_class_timer);
-	} else
+	if (!time_after_eq(jiffies, end))
+		mod_timer(&cfqd->idle_class_timer, end);
+	else
 		cfq_schedule_dispatch(cfqd);
 
 	spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);