Re: [PATCH 1/2] block: call blk_mq_exit_queue from disk_release for never added disks

[Ming Lei <ming.lei@redhat.com>]

On Mon, Jul 18, 2022 at 08:29:27AM +0200, Christoph Hellwig wrote:
> To undo the all initialization from blk_mq_init_allocated_queue in case
> of a probe failure where add_disk is never called we have to call
> blk_mq_exit_queue from put_disk.
> 
> We should be doing this in general, but can't do it for the normal
> teardown case (yet) as the tagset can be gone by the time the disk is
> released once it was added.  I hope to sort this out properly eventual
> but for now this isolated hack will do it.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  block/genhd.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/block/genhd.c b/block/genhd.c
> index 44dfcf67ed96a..ad8a3678d4480 100644
> --- a/block/genhd.c
> +++ b/block/genhd.c
> @@ -1138,6 +1138,18 @@ static void disk_release(struct device *dev)
>  	might_sleep();
>  	WARN_ON_ONCE(disk_live(disk));
>  
> +	/*
> +	 * To undo the all initialization from blk_mq_init_allocated_queue in
> +	 * case of a probe failure where add_disk is never called we have to
> +	 * call blk_mq_exit_queue here. We can't do this for the more common
> +	 * teardown case (yet) as the tagset can be gone by the time the disk
> +	 * is released once it was added.
> +	 */
> +	if (queue_is_mq(disk->queue) &&
> +	    test_bit(GD_OWNS_QUEUE, &disk->state) &&
> +	    !test_bit(GD_ADDED, &disk->state))
> +		blk_mq_exit_queue(disk->queue);
> +

Request queue is allocated successfully, but disk allocation may fail,
so blk_mq_exit_queue still may be missed in this case.


thanks,
Ming