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Commit e81ca6fe authored by Muthukumar Ratty's avatar Muthukumar Ratty Committed by James Bottomley
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[SCSI] block: Fix blk_execute_rq_nowait() dead queue handling 



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: default avatarMuthukumar Ratty <muthur@gmail.com>
Signed-off-by: default avatarBart Van Assche <bvanassche@acm.org>
Reviewed-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarJens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarJames Bottomley <JBottomley@Parallels.com>
parent 6548b0e5

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 */