blk-mq: fix race with timeouts and requeue events
If a requeue event races with a timeout, we can get into the
situation where we attempt to complete a request from the
timeout handler when it's not start anymore. This causes a crash.
So have the timeout handler check that REQ_ATOM_STARTED is still
set on the request - if not, we ignore the event. If this happens,
the request has now been marked as complete. As a consequence, we
need to ensure to clear REQ_ATOM_COMPLETE in blk_mq_start_request(),
as to maintain proper request state.
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/block/blk.h b/block/blk.h
index 1d880f1..79be2cb 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -37,9 +37,8 @@
void blk_rq_timed_out_timer(unsigned long data);
void blk_rq_check_expired(struct request *rq, unsigned long *next_timeout,
unsigned int *next_set);
-void __blk_add_timer(struct request *req, struct list_head *timeout_list);
+void blk_add_timer(struct request *req);
void blk_delete_timer(struct request *);
-void blk_add_timer(struct request *);
bool bio_attempt_front_merge(struct request_queue *q, struct request *req,