[bug,report] A race between blk_cleanup_queue and blk_timeout_work

Commit Message

Bart Van Assche Oct. 18, 2017, 4:39 p.m. UTC

On Tue, 2017-10-17 at 09:55 +0800, chenxiang (M) wrote:
> I find there is a race between blk_cleanup_queue and blk_timeout_work 

Thanks for the detailed report. Would it be possible to test the patch below
(applies on top of https://github.com/bvanassche/linux/tree/blk-mq-pm-2017-10-18-v10)?

Thanks,

Bart.


Subject: [PATCH] block: Fix race between blk_cleanup_queue() and timeout handling

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) <[e-mail]>
Signed-off-by: Bart Van Assche <[e-mail]>
Cc: Christoph Hellwig <[e-mail]>
Cc: Hannes Reinecke <[e-mail]>
Cc: Ming Lei <[e-mail]>
Cc: Johannes Thumshirn <[e-mail]>
---
 block/blk-core.c    | 1 +
 block/blk-timeout.c | 3 ---
 2 files changed, 1 insertion(+), 3 deletions(-)

Patch

diff --git a/block/blk-core.c b/block/blk-core.c
index 4fc9d6d44edd..16f2aa73696e 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -333,6 +333,7 @@  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;
diff --git a/block/blk-timeout.c b/block/blk-timeout.c
index 1eba71486716..764ecf9aeb30 100644
--- a/block/blk-timeout.c
+++ b/block/blk-timeout.c
@@ -134,8 +134,6 @@  void blk_timeout_work(struct work_struct *work)
 	struct request *rq, *tmp;
 	int next_set = 0;
 
-	if (blk_queue_enter(q, BLK_MQ_REQ_NOWAIT | BLK_MQ_REQ_PREEMPT))
-		return;
 	spin_lock_irqsave(q->queue_lock, flags);
 
 	list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list)
@@ -145,7 +143,6 @@  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);
 }
 
 /**