linux-kernel - Re: [PATCH V2 04/20] nvdimm/label: CXL labels skip the need for 'interleave-set cookie'

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Message-ID: <a05bbfe7-dec6-4858-8f9f-9f80deda48ae@intel.com>
Date: Fri, 15 Aug 2025 14:02:10 -0700
From: Dave Jiang <dave.jiang@...el.com>
To: Neeraj Kumar <s.neeraj@...sung.com>, linux-cxl@...r.kernel.org,
 nvdimm@...ts.linux.dev, linux-kernel@...r.kernel.org, gost.dev@...sung.com
Cc: a.manzanares@...sung.com, vishak.g@...sung.com, neeraj.kernel@...il.com
Subject: Re: [PATCH V2 04/20] nvdimm/label: CXL labels skip the need for
 'interleave-set cookie'



On 7/30/25 5:11 AM, Neeraj Kumar wrote:
> CXL LSA v2.1 utilizes the region labels stored in the LSA for interleave
> set configuration instead of interleave-set cookie used in previous LSA
> versions. As interleave-set cookie is not required for CXL LSA v2.1 format
> so skip its usage for CXL LSA 2.1 format
> 
> Signed-off-by: Neeraj Kumar <s.neeraj@...sung.com>
> ---
>  drivers/nvdimm/namespace_devs.c | 3 ++-
>  drivers/nvdimm/region_devs.c    | 5 +++++
>  2 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
> index bdf1ed6f23d8..5b73119dc8fd 100644
> --- a/drivers/nvdimm/namespace_devs.c
> +++ b/drivers/nvdimm/namespace_devs.c
> @@ -1692,7 +1692,8 @@ static struct device *create_namespace_pmem(struct nd_region *nd_region,
>  	int rc = 0;
>  	u16 i;
>  
> -	if (cookie == 0) {
> +	/* CXL labels skip the need for 'interleave-set cookie' */

This comment doesn't make sense to me. If it's a CXL label, we continue to execute. There's no skipping. Or are you trying to say if it's CXL label, then checking of cookie value is unnecessary? But the cookie value still is being used later on. Maybe a bit more comments on what's going on here would be helpful.

DJ

> +	if (!ndd->cxl && cookie == 0) {
>  		dev_dbg(&nd_region->dev, "invalid interleave-set-cookie\n");
>  		return ERR_PTR(-ENXIO);
>  	}
> diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
> index de1ee5ebc851..2debe60f8bf0 100644
> --- a/drivers/nvdimm/region_devs.c
> +++ b/drivers/nvdimm/region_devs.c
> @@ -858,6 +858,11 @@ u64 nd_region_interleave_set_cookie(struct nd_region *nd_region,
>  	if (!nd_set)
>  		return 0;
>  
> +	/* CXL labels skip the need for 'interleave-set cookie' */
> +	if (nsindex && __le16_to_cpu(nsindex->major) == 2
> +			&& __le16_to_cpu(nsindex->minor) == 1)
> +		return 0;
> +
>  	if (nsindex && __le16_to_cpu(nsindex->major) == 1
>  			&& __le16_to_cpu(nsindex->minor) == 1)
>  		return nd_set->cookie1;