Commit 96c51ce9 authored Jun 27, 2005 by Jens Axboe Committed by Linus Torvalds Jun 27, 2005

[PATCH] CFQ io scheduler: scheduler switch oops



If cfq is managing a queue and a new scheduler is later selected, it is
possible for the cfqd unplug_work work to be queued after the kblockd
work struct has been flushed.  The problem is the ordering of
cfq_shutdown_timer_wq() and blk_put_queue() in cfq_put_cfqd().  The
latter may rearm the work, leaving cfq_kick_queue() with dead data.

Signed-off-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

parent 52a5e15f

drivers/block/cfq-iosched.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -2249,10 +2249,11 @@ static void cfq_put_cfqd(struct cfq_data *cfqd)
		if (!atomic_dec_and_test(&cfqd->ref))
		return;

		cfq_shutdown_timer_wq(cfqd);

		blk_put_queue(q);

		cfq_shutdown_timer_wq(cfqd);
		q->elevator->elevator_data = NULL;

		mempool_destroy(cfqd->crq_pool);
		kfree(cfqd->crq_hash);
		kfree(cfqd->cfq_hash);

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