[SCSI] block: Fix blk_execute_rq_nowait() dead queue handling (e81ca6fe) · Commits · 戴 / test

If the queue is dead blk_execute_rq_nowait() doesn't invoke the done() callback function. That will result in blk_execute_rq() being stuck in wait_for_completion(). Avoid this by initializing rq->end_io to the done() callback before we check the queue state. Also, make sure the queue lock is held around the invocation of the done() callback. Found this through source code review. Signed-off-by:

Muthukumar Ratty <muthur@gmail.com> Signed-off-by:

Bart Van Assche <bvanassche@acm.org> Reviewed-by:

Tejun Heo <tj@kernel.org> Acked-by:

Jens Axboe <axboe@kernel.dk> Signed-off-by:

James Bottomley <JBottomley@Parallels.com>

block/blk-exec.c

+8 −3

Original line number	Diff line number	Diff line
		@@ -43,6 +43,9 @@ static void blk_end_sync_rq(struct request *rq, int error)
		* Description:
		* Insert a fully prepared request at the back of the I/O scheduler queue
		* for execution. Don't wait for completion.
		*
		* Note:
		* This function will invoke @done directly if the queue is dead.
		*/
		void blk_execute_rq_nowait(struct request_queue q, struct gendisk bd_disk,
		struct request *rq, int at_head,
		@@ -51,18 +54,20 @@ void blk_execute_rq_nowait(struct request_queue q, struct gendisk bd_disk,
		int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;

		WARN_ON(irqs_disabled());

		rq->rq_disk = bd_disk;
		rq->end_io = done;

		spin_lock_irq(q->queue_lock);

		if (unlikely(blk_queue_dead(q))) {
		spin_unlock_irq(q->queue_lock);
		rq->errors = -ENXIO;
		if (rq->end_io)
		rq->end_io(rq, rq->errors);
		spin_unlock_irq(q->queue_lock);
		return;
		}

		rq->rq_disk = bd_disk;
		rq->end_io = done;
		__elv_add_request(q, rq, where);
		__blk_run_queue(q);
		/* the queue is stopped so it won't be run */

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