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Commit ae818a38 authored by Jens Axboe's avatar Jens Axboe
Browse files

[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: default avatarJens Axboe <axboe@suse.de>
parent 25776e35

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);