Message-ID: <534936cc-4ecc-46e5-8196-bc3992e086ab@intel.com>
Date: Fri, 15 Aug 2025 14:55:40 -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 05/20] nvdimm/region_label: Add region label updation
 routine



On 7/30/25 5:11 AM, Neeraj Kumar wrote:
> Added __pmem_region_label_update region label update routine to update
> region label.
> 
> Also used guard(mutex)(&nd_mapping->lock) in place of mutex_lock() and
> mutex_unlock()
> 
> Signed-off-by: Neeraj Kumar <s.neeraj@...sung.com>

Subject, s/updation/update/ ?

> ---
>  drivers/nvdimm/label.c          | 171 +++++++++++++++++++++++++++++---
>  drivers/nvdimm/label.h          |   2 +
>  drivers/nvdimm/namespace_devs.c |  12 +++
>  drivers/nvdimm/nd.h             |  20 ++++
>  include/linux/libnvdimm.h       |   8 ++
>  5 files changed, 198 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/nvdimm/label.c b/drivers/nvdimm/label.c
> index 3f8a6bdb77c7..94f2d0ba7aca 100644
> --- a/drivers/nvdimm/label.c
> +++ b/drivers/nvdimm/label.c
> @@ -381,6 +381,16 @@ static void nsl_calculate_checksum(struct nvdimm_drvdata *ndd,
>  	nsl_set_checksum(ndd, nd_label, sum);
>  }
>  
> +static void rgl_calculate_checksum(struct nvdimm_drvdata *ndd,

region_label_checksum()? rgl/rg is just a bit jarring to read even though I get nvdimm already has nd and nsl etc.

> +				   struct cxl_region_label *rg_label)

Prefer just spell out region_label

> +{
> +	u64 sum;
> +
> +	rgl_set_checksum(rg_label, 0);
> +	sum = nd_fletcher64(rg_label, sizeof_namespace_label(ndd), 1);
> +	rgl_set_checksum(rg_label, sum);
> +}
> +
>  static bool slot_valid(struct nvdimm_drvdata *ndd,
>  		struct nd_lsa_label *lsa_label, u32 slot)
>  {
> @@ -960,7 +970,7 @@ static int __pmem_label_update(struct nd_region *nd_region,
>  		return rc;
>  
>  	/* Garbage collect the previous label */
> -	mutex_lock(&nd_mapping->lock);
> +	guard(mutex)(&nd_mapping->lock);
>  	list_for_each_entry(label_ent, &nd_mapping->labels, list) {
>  		if (!label_ent->label)
>  			continue;
> @@ -972,20 +982,20 @@ static int __pmem_label_update(struct nd_region *nd_region,
>  	/* update index */
>  	rc = nd_label_write_index(ndd, ndd->ns_next,
>  			nd_inc_seq(__le32_to_cpu(nsindex->seq)), 0);
> -	if (rc == 0) {
> -		list_for_each_entry(label_ent, &nd_mapping->labels, list)
> -			if (!label_ent->label) {
> -				label_ent->label = lsa_label;
> -				lsa_label = NULL;
> -				break;
> -			}
> -		dev_WARN_ONCE(&nspm->nsio.common.dev, lsa_label,
> -				"failed to track label: %d\n",
> -				to_slot(ndd, lsa_label));
> -		if (lsa_label)
> -			rc = -ENXIO;
> -	}
> -	mutex_unlock(&nd_mapping->lock);
> +	if (rc)
> +		return rc;
> +
> +	list_for_each_entry(label_ent, &nd_mapping->labels, list)
> +		if (!label_ent->label) {
> +			label_ent->label = lsa_label;
> +			lsa_label = NULL;
> +			break;
> +		}

Would've preferred the original code to look like:

list_for_each_entry(label_ent, &nd_mapping->labels, list) {
	if (label_ent->label)
		continue;

	label_ent->label = lsa_label;
	lsa_label = NULL;
	break;
}

But ah well....

> +	dev_WARN_ONCE(&nspm->nsio.common.dev, lsa_label,> +			"failed to track label: %d\n",
> +			to_slot(ndd, lsa_label));
> +	if (lsa_label)
> +		rc = -ENXIO;

Just return here as Jonathan already mentioned. guard() helps with cleaning that up.

>  
>  	return rc;
>  }
> @@ -1127,6 +1137,137 @@ int nd_pmem_namespace_label_update(struct nd_region *nd_region,
>  	return 0;
>  }
>  
> +static int __pmem_region_label_update(struct nd_region *nd_region,
> +		struct nd_mapping *nd_mapping, int pos, unsigned long flags)
> +{
> +	struct nd_interleave_set *nd_set = nd_region->nd_set;
> +	struct nvdimm_drvdata *ndd = to_ndd(nd_mapping);
> +	struct nd_lsa_label *nd_label;
> +	struct cxl_region_label *rg_label;
> +	struct nd_namespace_index *nsindex;> +	struct nd_label_ent *label_ent;
> +	unsigned long *free;
> +	u32 nslot, slot;
> +	size_t offset;
> +	int rc;
> +	uuid_t tmp;

uuid instead of tmp would make the variable clearer to read

Also please arrange variable ordering in reverse xmas tree. 

> +
> +	if (!preamble_next(ndd, &nsindex, &free, &nslot))
> +		return -ENXIO;
> +
> +	/* allocate and write the label to the staging (next) index */
> +	slot = nd_label_alloc_slot(ndd);
> +	if (slot == UINT_MAX)
> +		return -ENXIO;
> +	dev_dbg(ndd->dev, "allocated: %d\n", slot);
> +
> +	nd_label = to_label(ndd, slot);
> +
> +	memset(nd_label, 0, sizeof_namespace_label(ndd));
> +	rg_label = &nd_label->rg_label;
> +
> +	/* Set Region Label Format identification UUID */
> +	uuid_parse(CXL_REGION_UUID, &tmp);
> +	export_uuid(nd_label->rg_label.type, &tmp);
> +
> +	/* Set Current Region Label UUID */
> +	export_uuid(nd_label->rg_label.uuid, &nd_set->uuid);
> +
> +	rg_label->flags = __cpu_to_le32(flags);
> +	rg_label->nlabel = __cpu_to_le16(nd_region->ndr_mappings);
> +	rg_label->position = __cpu_to_le16(pos);
> +	rg_label->dpa = __cpu_to_le64(nd_mapping->start);
> +	rg_label->rawsize = __cpu_to_le64(nd_mapping->size);
> +	rg_label->hpa = __cpu_to_le64(nd_set->res->start);
> +	rg_label->slot = __cpu_to_le32(slot);
> +	rg_label->ig = __cpu_to_le32(nd_set->interleave_granularity);
> +	rg_label->align = __cpu_to_le16(0);
> +
> +	/* Update fletcher64 Checksum */
> +	rgl_calculate_checksum(ndd, rg_label);
> +
> +	/* update label */
> +	offset = nd_label_offset(ndd, nd_label);
> +	rc = nvdimm_set_config_data(ndd, offset, nd_label,
> +			sizeof_namespace_label(ndd));
> +	if (rc < 0) {
> +		nd_label_free_slot(ndd, slot);
> +		return rc;
> +	}
> +
> +	/* Garbage collect the previous label */
> +	guard(mutex)(&nd_mapping->lock);
> +	list_for_each_entry(label_ent, &nd_mapping->labels, list) {
> +		if (!label_ent->label)
> +			continue;
> +		if (rgl_uuid_equal(&label_ent->label->rg_label, &nd_set->uuid))
> +			reap_victim(nd_mapping, label_ent);
> +	}
> +
> +	/* update index */
> +	rc = nd_label_write_index(ndd, ndd->ns_next,
> +			nd_inc_seq(__le32_to_cpu(nsindex->seq)), 0);
> +	if (rc)
> +		return rc;
> +
> +	list_for_each_entry(label_ent, &nd_mapping->labels, list)
> +		if (!label_ent->label) {
> +			label_ent->label = nd_label;
> +			nd_label = NULL;
> +			break;
> +		}
> +	dev_WARN_ONCE(&nd_region->dev, nd_label,
> +			"failed to track label: %d\n",
> +			to_slot(ndd, nd_label));
> +	if (nd_label)
> +		rc = -ENXIO;
just return here

> +
> +	return rc;
> +}
> +
> +int nd_pmem_region_label_update(struct nd_region *nd_region)
> +{
> +	int i, rc;
> +
> +	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);
> +
> +		/* No need to update region label for non cxl format */
> +		if (!ndd->cxl)
> +			continue;

Would there be a mix of different nd mappings? I wonder if you can just 'return 0' if you find ndd->cxl on the first one and just skip everything.

> +
> +		/* Init labels to include region label */
> +		rc = init_labels(nd_mapping, 1);
> +
> +		if (rc < 0)
> +			return rc;
> +
> +		rc = __pmem_region_label_update(nd_region, nd_mapping, i,
> +					NSLABEL_FLAG_UPDATING);
> +
> +		if (rc)
> +			return rc;
> +	}
> +
> +	/* Clear the UPDATING flag per UEFI 2.7 expectations */
> +	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);
> +
> +		/* No need to update region label for non cxl format */
> +		if (!ndd->cxl)
> +			continue;
> +> +		rc = __pmem_region_label_update(nd_region, nd_mapping, i, 0);
> +
> +		if (rc)
> +			return rc;
> +	}
> +
> +	return 0;
> +}
> +
>  int __init nd_label_init(void)
>  {
>  	WARN_ON(guid_parse(NVDIMM_BTT_GUID, &nvdimm_btt_guid));
> diff --git a/drivers/nvdimm/label.h b/drivers/nvdimm/label.h
> index 4883b3a1320f..0f428695017d 100644
> --- a/drivers/nvdimm/label.h
> +++ b/drivers/nvdimm/label.h
> @@ -190,6 +190,7 @@ struct nd_namespace_label {
>  struct nd_lsa_label {
>  	union {
>  		struct nd_namespace_label ns_label;
> +		struct cxl_region_label rg_label;
>  	};
>  };
>  
> @@ -233,4 +234,5 @@ struct nd_region;
>  struct nd_namespace_pmem;
>  int nd_pmem_namespace_label_update(struct nd_region *nd_region,
>  		struct nd_namespace_pmem *nspm, resource_size_t size);
> +int nd_pmem_region_label_update(struct nd_region *nd_region);
>  #endif /* __LABEL_H__ */
> diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
> index 5b73119dc8fd..02ae8162566c 100644
> --- a/drivers/nvdimm/namespace_devs.c
> +++ b/drivers/nvdimm/namespace_devs.c
> @@ -232,6 +232,18 @@ static ssize_t __alt_name_store(struct device *dev, const char *buf,
>  	return rc;
>  }
>  
> +int nd_region_label_update(struct nd_region *nd_region)
> +{
> +	int rc;
> +
> +	nvdimm_bus_lock(&nd_region->dev);
> +	rc = nd_pmem_region_label_update(nd_region);
> +	nvdimm_bus_unlock(&nd_region->dev);
> +
> +	return rc;
> +}
> +EXPORT_SYMBOL_GPL(nd_region_label_update);
> +
>  static int nd_namespace_label_update(struct nd_region *nd_region,
>  		struct device *dev)
>  {
> diff --git a/drivers/nvdimm/nd.h b/drivers/nvdimm/nd.h
> index 651847f1bbf9..15d94e3937f0 100644
> --- a/drivers/nvdimm/nd.h
> +++ b/drivers/nvdimm/nd.h
> @@ -322,6 +322,26 @@ static inline void nsl_set_region_uuid(struct nvdimm_drvdata *ndd,
>  		export_uuid(ns_label->cxl.region_uuid, uuid);
>  }
>  
> +static inline bool rgl_uuid_equal(struct cxl_region_label *rg_label,
> +				  const uuid_t *uuid)

region_label_uuid_equal() and region_label

> +{
> +	uuid_t tmp;

tmp_uuid

> +
> +	import_uuid(&tmp, rg_label->uuid);
> +	return uuid_equal(&tmp, uuid);
> +}
> +
> +static inline u64 rgl_get_checksum(struct cxl_region_label *rg_label)

region_label_get_checksum()

> +{
> +	return __le64_to_cpu(rg_label->checksum);
> +}
> +
> +static inline void rgl_set_checksum(struct cxl_region_label *rg_label,
region_label_set_checksum()

> +				    u64 checksum)
> +{
> +	rg_label->checksum = __cpu_to_le64(checksum);
> +}
> +
>  bool nsl_validate_type_guid(struct nvdimm_drvdata *ndd,
>  			    struct nd_namespace_label *nd_label, guid_t *guid);
>  enum nvdimm_claim_class nsl_get_claim_class(struct nvdimm_drvdata *ndd,
> diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h
> index 0a55900842c8..b06bd45373f4 100644
> --- a/include/linux/libnvdimm.h
> +++ b/include/linux/libnvdimm.h
> @@ -115,6 +115,13 @@ struct nd_interleave_set {
>  	u64 altcookie;
>  
>  	guid_t type_guid;
> +
> +	/* v2.1 region label info */
> +	uuid_t uuid;
> +	int interleave_ways;
> +	int interleave_granularity;
> +	struct resource *res;
> +	int nr_targets;
>  };
>  
>  struct nd_mapping_desc {
> @@ -302,6 +309,7 @@ int nvdimm_has_flush(struct nd_region *nd_region);
>  int nvdimm_has_cache(struct nd_region *nd_region);
>  int nvdimm_in_overwrite(struct nvdimm *nvdimm);
>  bool is_nvdimm_sync(struct nd_region *nd_region);
> +int nd_region_label_update(struct nd_region *nd_region);
>  
>  static inline int nvdimm_ctl(struct nvdimm *nvdimm, unsigned int cmd, void *buf,
>  		unsigned int buf_len, int *cmd_rc)

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