Re: [PATCH 1/2] block: also mark disk-owned queues as dying in __blk_mark_disk_dead

[Sergey Senozhatsky <senozhatsky@chromium.org>]

On (24/10/08 13:57), Christoph Hellwig wrote:
> When del_gendisk shuts down access to a gendisk, it could lead to a
> deadlock with sd or, which try to submit passthrough SCSI commands from
> their ->release method under open_mutex.  The submission can be blocked
> in blk_enter_queue while del_gendisk can't get to actually telling them
> top stop and wake them up.
> 
> As the disk is going away there is no real point in sending these
> commands, but we have no really good way to distinguish between the
> cases.  For now mark even standalone (aka SCSI queues) as dying in
> del_gendisk to avoid this deadlock, but the real fix will be to split
> freeing a disk from freezing a queue for not disk associated requests.
> 
> Reported-by: Sergey Senozhatsky <senozhatsky@chromium.org>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

FWIW
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>

[..]

>  	if (!test_bit(GD_OWNS_QUEUE, &disk->state)) {
> +		if (test_bit(QUEUE_FLAG_RESURRECT, &q->queue_flags))
> +			clear_bit(QUEUE_FLAG_DYING, &q->queue_flags);

Don't know if we also want to clear QUEUE_FLAG_RESURRECT here, just in
case.

>  		blk_queue_flag_clear(QUEUE_FLAG_INIT_DONE, q);
>  		__blk_mq_unfreeze_queue(q, true);
>  	} else {