Re: [PATCH v4 04/10] blk-mq: Check blk_mq_debugfs_register() return value

[Omar Sandoval <osandov@osandov.com>]

On Fri, Apr 21, 2017 at 04:40:20PM -0700, Bart Van Assche wrote:
> Make __blk_mq_register_dev() check the blk_mq_debugfs_register()
> return value.

I intentionally didn't check this. In my opinion, a missing debug
directory shouldn't be fatal.

> In the error path, only unregister hctxs for which
> registration succeeded.

This part of it seems reasonable.

> Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
> Cc: Omar Sandoval <osandov@fb.com>
> Cc: Hannes Reinecke <hare@suse.com>
> ---
>  block/blk-mq-sysfs.c | 23 +++++++++++++++++------
>  1 file changed, 17 insertions(+), 6 deletions(-)
> 
> diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c
> index c2cac20d981d..5f66a7798878 100644
> --- a/block/blk-mq-sysfs.c
> +++ b/block/blk-mq-sysfs.c
> @@ -318,21 +318,32 @@ int __blk_mq_register_dev(struct device *dev, struct request_queue *q)
>  
>  	kobject_uevent(&q->mq_kobj, KOBJ_ADD);
>  
> -	blk_mq_debugfs_register(q);
> +	ret = blk_mq_debugfs_register(q);
> +	if (ret)
> +		goto remove;
>  
>  	queue_for_each_hw_ctx(q, hctx, i) {
>  		ret = blk_mq_register_hctx(hctx);
>  		if (ret)
> -			break;
> +			goto unreg;
>  	}
>  
> -	if (ret)
> -		__blk_mq_unregister_dev(dev, q);
> -	else
> -		q->mq_sysfs_init_done = true;
> +	q->mq_sysfs_init_done = true;
>  
>  out:
>  	return ret;
> +
> +unreg:
> +	while (--i >= 0)
> +		blk_mq_unregister_hctx(hctx);
> +
> +	blk_mq_debugfs_unregister_mq(q);
> +
> +remove:
> +	kobject_uevent(&q->mq_kobj, KOBJ_REMOVE);
> +	kobject_del(&q->mq_kobj);
> +	kobject_put(&dev->kobj);
> +	goto out;
>  }
>  
>  int blk_mq_register_dev(struct device *dev, struct request_queue *q)
> -- 
> 2.12.2
>