[PATCH] cfq-iosched: fix bug in timer handling for the idle class (ae818a38) · Commits · 戴 / test

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 <axboe@suse.de>

block/cfq-iosched.c

+3 −4

Original line number	Diff line number	Diff line
		@@ -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);

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