block: Fix race triggered by blk_set_queue_dying()

blk_set_queue_dying() can be called while another thread is
submitting I/O or changing queue flags, e.g. through dm_stop_queue().
Hence protect the QUEUE_FLAG_DYING flag change with locking.

Signed-off-by: Bart Van Assche <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Mike Snitzer <[email protected]>
Cc: stable <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

diff --git a/block/blk-core.c b/block/blk-core.c
index 999442ec4601487a35c76dad156dfa438a2a35b3..36c7ac328d8c17bd1967f898c91ff49f7a9b050d 100644 (file)
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -515,7 +515,9 @@ EXPORT_SYMBOL_GPL(blk_queue_bypass_end);
 
 void blk_set_queue_dying(struct request_queue *q)
 {
-       queue_flag_set_unlocked(QUEUE_FLAG_DYING, q);
+       spin_lock_irq(q->queue_lock);
+       queue_flag_set(QUEUE_FLAG_DYING, q);
+       spin_unlock_irq(q->queue_lock);
 
        if (q->mq_ops)
                blk_mq_wake_waiters(q);