[SRU][Xenial][PATCH 1/1] block: Fix a race between blk_cleanup_queue() and timeout handling

[Joseph Salisbury]

From: Bart Van Assche <bart.vanassche at wdc.com>

BugLink: https://bugs.launchpad.net/bugs/1791790

Make sure that if the timeout timer fires after a queue has been
marked "dying" that the affected requests are finished.

Reported-by: chenxiang (M) <chenxiang66 at hisilicon.com>
Fixes: commit 287922eb0b18 ("block: defer timeouts to a workqueue")
Signed-off-by: Bart Van Assche <bart.vanassche at wdc.com>
Tested-by: chenxiang (M) <chenxiang66 at hisilicon.com>
Cc: Christoph Hellwig <hch at lst.de>
Cc: Keith Busch <keith.busch at intel.com>
Cc: Hannes Reinecke <hare at suse.com>
Cc: Ming Lei <ming.lei at redhat.com>
Cc: Johannes Thumshirn <jthumshirn at suse.de>
Cc: <stable at vger.kernel.org>
Signed-off-by: Jens Axboe <axboe at kernel.dk>
(cherry picked from commit 4e9b6f20828ac880dbc1fa2fdbafae779473d1af)
Signed-off-by: Joseph Salisbury <joseph.salisbury at canonical.com>
---
 block/blk-core.c    | 2 ++
 block/blk-timeout.c | 3 ---
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index be184a8..13c1e5c 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -266,6 +266,7 @@ EXPORT_SYMBOL(blk_stop_queue);
 void blk_sync_queue(struct request_queue *q)
 {
 	del_timer_sync(&q->timeout);
+	cancel_work_sync(&q->timeout_work);
 
 	if (q->mq_ops) {
 		struct blk_mq_hw_ctx *hctx;
@@ -701,6 +702,7 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
 	setup_timer(&q->backing_dev_info->laptop_mode_wb_timer,
 		    laptop_mode_timer_fn, (unsigned long) q);
 	setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
+	INIT_WORK(&q->timeout_work, NULL);
 	INIT_LIST_HEAD(&q->queue_head);
 	INIT_LIST_HEAD(&q->timeout_list);
 	INIT_LIST_HEAD(&q->icq_list);
diff --git a/block/blk-timeout.c b/block/blk-timeout.c
index 7c176f6..aedd128 100644
--- a/block/blk-timeout.c
+++ b/block/blk-timeout.c
@@ -135,8 +135,6 @@ void blk_timeout_work(struct work_struct *work)
 	struct request *rq, *tmp;
 	int next_set = 0;
 
-	if (blk_queue_enter(q, true))
-		return;
 	spin_lock_irqsave(q->queue_lock, flags);
 
 	list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list)
@@ -146,7 +144,6 @@ void blk_timeout_work(struct work_struct *work)
 		mod_timer(&q->timeout, round_jiffies_up(next));
 
 	spin_unlock_irqrestore(q->queue_lock, flags);
-	blk_queue_exit(q);
 }
 
 /**
-- 
2.7.4