linux-kernel - Re: [PATCH v3 2/2] nvdimm: Remove dead code for ENODEV checking in scan

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Message-ID: <66c6396577ab9_1719d2945@iweiny-mobl.notmuch>
Date: Wed, 21 Aug 2024 14:00:53 -0500
From: Ira Weiny <ira.weiny@...el.com>
To: Li Zhijian <lizhijian@...itsu.com>, <nvdimm@...ts.linux.dev>
CC: <dan.j.williams@...el.com>, <vishal.l.verma@...el.com>,
	<dave.jiang@...el.com>, <ira.weiny@...el.com>,
	<linux-kernel@...r.kernel.org>, Li Zhijian <lizhijian@...itsu.com>
Subject: Re: [PATCH v3 2/2] nvdimm: Remove dead code for ENODEV checking in
 scan_labels()

Li Zhijian wrote:
> The only way create_namespace_pmem() returns an ENODEV code is if
> select_pmem_id(nd_region, &uuid) returns ENODEV when its 2nd parameter
> is a null pointer. However, this is impossible because &uuid is always
> valid.
> 
> Furthermore, create_namespace_pmem() is the only user of
> select_pmem_id(), it's safe to remove the 'return -ENODEV' branch.
> 
> Signed-off-by: Li Zhijian <lizhijian@...itsu.com>

Reviewed-by: Ira Weiny <ira.weiny@...el.com>

> ---
> V2:
>   new patch.
>   It's found when I'm Reviewing/tracing the return values of create_namespace_pmem()
> ---
>  drivers/nvdimm/namespace_devs.c | 9 ---------
>  1 file changed, 9 deletions(-)
> 
> diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
> index 35d9f3cc2efa..55cfbf1e0a95 100644
> --- a/drivers/nvdimm/namespace_devs.c
> +++ b/drivers/nvdimm/namespace_devs.c
> @@ -1612,9 +1612,6 @@ static int select_pmem_id(struct nd_region *nd_region, const uuid_t *pmem_id)
>  {
>  	int i;
>  
> -	if (!pmem_id)
> -		return -ENODEV;
> -
>  	for (i = 0; i < nd_region->ndr_mappings; i++) {
>  		struct nd_mapping *nd_mapping = &nd_region->mapping[i];
>  		struct nvdimm_drvdata *ndd = to_ndd(nd_mapping);
> @@ -1790,9 +1787,6 @@ static struct device *create_namespace_pmem(struct nd_region *nd_region,
>  	case -EINVAL:
>  		dev_dbg(&nd_region->dev, "invalid label(s)\n");
>  		break;
> -	case -ENODEV:
> -		dev_dbg(&nd_region->dev, "label not found\n");
> -		break;
>  	default:
>  		dev_dbg(&nd_region->dev, "unexpected err: %d\n", rc);
>  		break;
> @@ -1980,9 +1974,6 @@ static struct device **scan_labels(struct nd_region *nd_region)
>  			case -EAGAIN:
>  				/* skip invalid labels */
>  				continue;
> -			case -ENODEV:
> -				/* fallthrough to seed creation */
> -				break;
>  			default:
>  				goto err;
>  			}
> -- 
> 2.29.2
>