queue/blk-mq-move-cancel-of-requeue_work-to-the-front-of-b.patch

From 693ccf68871b8d29c5c346576673d067dba03adf Mon Sep 17 00:00:00 2001
From: zhengbin <zhengbin13@huawei.com>
Date: Mon, 12 Aug 2019 20:36:55 +0800
Subject: [PATCH] blk-mq: move cancel of requeue_work to the front of
 blk_exit_queue

commit e26cc08265dda37d2acc8394604f220ef412299d upstream.

blk_exit_queue will free elevator_data, while blk_mq_requeue_work
will access it. Move cancel of requeue_work to the front of
blk_exit_queue to avoid use-after-free.

blk_exit_queue                blk_mq_requeue_work
  __elevator_exit               blk_mq_run_hw_queues
    blk_mq_exit_sched             blk_mq_run_hw_queue
      dd_exit_queue                 blk_mq_hctx_has_pending
        kfree(elevator_data)          blk_mq_sched_has_work
                                        dd_has_work

Fixes: fbc2a15e3433 ("blk-mq: move cancel of requeue_work into blk_mq_release")
Cc: stable@vger.kernel.org
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: zhengbin <zhengbin13@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 01f5660aae64..5f1493fc9c7f 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2420,8 +2420,6 @@ void blk_mq_release(struct request_queue *q)
 	struct blk_mq_hw_ctx *hctx;
 	unsigned int i;
 
-	cancel_delayed_work_sync(&q->requeue_work);
-
 	/* hctx kobj stays in hctx */
 	queue_for_each_hw_ctx(q, hctx, i) {
 		if (!hctx)
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 96c7dfc04852..d1f9118a1036 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -821,6 +821,9 @@ static void __blk_release_queue(struct work_struct *work)
 
 	blk_free_queue_stats(q->stats);
 
+	if (queue_is_mq(q))
+		cancel_delayed_work_sync(&q->requeue_work);
+
 	blk_exit_rl(q, &q->root_rl);
 
 	if (q->queue_tags)
-- 
2.7.4