queue/blk-mq-move-cancel-of-requeue_work-into-blk_mq_relea.patch

From aec7c12e99f767f0583d489d3862b25536afedb4 Mon Sep 17 00:00:00 2001
From: Ming Lei <ming.lei@redhat.com>
Date: Tue, 30 Apr 2019 09:52:24 +0800
Subject: [PATCH] blk-mq: move cancel of requeue_work into blk_mq_release

commit fbc2a15e3433058582e5635aabe48a3011a644a8 upstream.

With holding queue's kobject refcount, it is safe for driver
to schedule requeue. However, blk_mq_kick_requeue_list() may
be called after blk_sync_queue() is done because of concurrent
requeue activities, then requeue work may not be completed when
freeing queue, and kernel oops is triggered.

So moving the cancel of requeue_work into blk_mq_release() for
avoiding race between requeue and freeing queue.

Cc: Dongli Zhang <dongli.zhang@oracle.com>
Cc: James Smart <james.smart@broadcom.com>
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: linux-scsi@vger.kernel.org,
Cc: Martin K . Petersen <martin.petersen@oracle.com>,
Cc: Christoph Hellwig <hch@lst.de>,
Cc: James E . J . Bottomley <jejb@linux.vnet.ibm.com>,
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: James Smart <james.smart@broadcom.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/block/blk-core.c b/block/blk-core.c
index 7d4bf916546c..fc41adedf2eb 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -411,7 +411,6 @@ void blk_sync_queue(struct request_queue *q)
 		struct blk_mq_hw_ctx *hctx;
 		int i;
 
-		cancel_delayed_work_sync(&q->requeue_work);
 		queue_for_each_hw_ctx(q, hctx, i)
 			cancel_delayed_work_sync(&hctx->run_work);
 	} else {
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 5f1493fc9c7f..01f5660aae64 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2420,6 +2420,8 @@ 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)
-- 
2.7.4