From 96c51ce94e8415d2dfb08358bbd50e1589111f33 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Mon, 27 Jun 2005 14:49:39 +0200 Subject: [PATCH] [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 Signed-off-by: Linus Torvalds --- drivers/block/cfq-iosched.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/block/cfq-iosched.c b/drivers/block/cfq-iosched.c index 1ecb179b8604..ff1cc968f96d 100644 --- a/drivers/block/cfq-iosched.c +++ b/drivers/block/cfq-iosched.c @@ -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); -- 2.11.0