devm_cxl_pmem_add_region() is used to create cxl region based on region
information scanned from LSA.

devm_cxl_add_region() is used to just allocate cxlr and its fields are
filled later by userspace tool using device attributes (*_store()).

Inspiration for devm_cxl_pmem_add_region() is taken from these device
attributes (_store*) calls. It allocates cxlr and fills information
parsed from LSA and calls device_add(&cxlr->dev) to initiate further
region creation porbes

Rename __create_region() to cxl_create_region(), which will be used
in later patch to create cxl region after fetching region information
from LSA.

Signed-off-by: Neeraj Kumar <s.neeraj@samsung.com>
---
 drivers/cxl/core/core.h   |  12 ++++
 drivers/cxl/core/region.c | 124 ++++++++++++++++++++++++++++++++++++--
 2 files changed, 131 insertions(+), 5 deletions(-)

diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
index 1fb66132b777..fde96507cb75 100644
--- a/drivers/cxl/core/core.h
+++ b/drivers/cxl/core/core.h
@@ -42,6 +42,10 @@ int cxl_get_poison_by_endpoint(struct cxl_port *port);
 struct cxl_region *cxl_dpa_to_region(const struct cxl_memdev *cxlmd, u64 dpa);
 u64 cxl_dpa_to_hpa(struct cxl_region *cxlr, const struct cxl_memdev *cxlmd,
 		   u64 dpa);
+struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
+				     enum cxl_partition_mode mode, int id,
+				     struct cxl_pmem_region_params *params,
+				     struct cxl_decoder *cxld);
 
 #else
 static inline u64 cxl_dpa_to_hpa(struct cxl_region *cxlr,
@@ -71,6 +75,14 @@ static inline int cxl_region_init(void)
 static inline void cxl_region_exit(void)
 {
 }
+static inline struct cxl_region *
+cxl_create_region(struct cxl_root_decoder *cxlrd,
+		  enum cxl_partition_mode mode, int id,
+		  struct cxl_pmem_region_params *params,
+		  struct cxl_decoder *cxld)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
 #define CXL_REGION_ATTR(x) NULL
 #define CXL_REGION_TYPE(x) NULL
 #define SET_CXL_REGION_ATTR(x)
diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 3c868c4de4ec..06a75f0a8e9b 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -2618,6 +2618,114 @@ static struct cxl_region *devm_cxl_add_region(struct cxl_root_decoder *cxlrd,
 	return ERR_PTR(rc);
 }
 
+static ssize_t alloc_region_hpa(struct cxl_region *cxlr, u64 size)
+{
+	int rc;
+
+	ACQUIRE(rwsem_write_kill, rwsem)(&cxl_rwsem.region);
+	if ((rc = ACQUIRE_ERR(rwsem_write_kill, &rwsem)))
+		return rc;
+
+	if (!size)
+		return -EINVAL;
+
+	return alloc_hpa(cxlr, size);
+}
+
+static ssize_t alloc_region_dpa(struct cxl_endpoint_decoder *cxled, u64 size)
+{
+	int rc;
+
+	if (!size)
+		return -EINVAL;
+
+	if (!IS_ALIGNED(size, SZ_256M))
+		return -EINVAL;
+
+	rc = cxl_dpa_free(cxled);
+	if (rc)
+		return rc;
+
+	return cxl_dpa_alloc(cxled, size);
+}
+
+static struct cxl_region *
+devm_cxl_pmem_add_region(struct cxl_root_decoder *cxlrd, int id,
+			 struct cxl_pmem_region_params *params,
+			 struct cxl_decoder *cxld,
+			 enum cxl_decoder_type type)
+{
+	struct cxl_endpoint_decoder *cxled;
+	struct cxl_region_params *p;
+	struct cxl_port *root_port;
+	struct device *dev;
+	int rc;
+
+	struct cxl_region *cxlr __free(put_cxl_region) =
+		cxl_region_alloc(cxlrd, id);
+	if (IS_ERR(cxlr))
+		return cxlr;
+
+	cxlr->mode = CXL_PARTMODE_PMEM;
+	cxlr->type = type;
+
+	dev = &cxlr->dev;
+	rc = dev_set_name(dev, "region%d", id);
+	if (rc)
+		return ERR_PTR(rc);
+
+	p = &cxlr->params;
+	p->uuid = params->uuid;
+	p->interleave_ways = params->nlabel;
+	p->interleave_granularity = params->ig;
+
+	rc = alloc_region_hpa(cxlr, params->rawsize);
+	if (rc)
+		return ERR_PTR(rc);
+
+	cxled = to_cxl_endpoint_decoder(&cxld->dev);
+
+	rc = cxl_dpa_set_part(cxled, CXL_PARTMODE_PMEM);
+	if (rc)
+		return ERR_PTR(rc);
+
+	rc = alloc_region_dpa(cxled, params->rawsize);
+	if (rc)
+		return ERR_PTR(rc);
+
+	/*
+	 * TODO: Currently we have support of interleave_way == 1, where
+	 * we can only have one region per mem device. It means mem device
+	 * position (params->position) will always be 0. It is therefore
+	 * attaching only one target at params->position
+	 */
+	if (params->position)
+		return ERR_PTR(-EOPNOTSUPP);
+
+	rc = attach_target(cxlr, cxled, params->position, TASK_INTERRUPTIBLE);
+	if (rc)
+		return ERR_PTR(rc);
+
+	rc = __commit(cxlr);
+	if (rc)
+		return ERR_PTR(rc);
+
+	rc = device_add(dev);
+	if (rc)
+		return ERR_PTR(rc);
+
+	root_port = to_cxl_port(cxlrd->cxlsd.cxld.dev.parent);
+	rc = devm_add_action_or_reset(root_port->uport_dev,
+			unregister_region, cxlr);
+	if (rc)
+		return ERR_PTR(rc);
+
+	dev_dbg(root_port->uport_dev, "%s: created %s\n",
+		dev_name(&cxlrd->cxlsd.cxld.dev), dev_name(dev));
+
+	return no_free_ptr(cxlr);
+}
+
 static ssize_t __create_region_show(struct cxl_root_decoder *cxlrd, char *buf)
 {
 	return sysfs_emit(buf, "region%u\n", atomic_read(&cxlrd->region_id));
@@ -2635,8 +2743,10 @@ static ssize_t create_ram_region_show(struct device *dev,
 	return __create_region_show(to_cxl_root_decoder(dev), buf);
 }
 
-static struct cxl_region *__create_region(struct cxl_root_decoder *cxlrd,
-					  enum cxl_partition_mode mode, int id)
+struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
+				     enum cxl_partition_mode mode, int id,
+				     struct cxl_pmem_region_params *pmem_params,
+				     struct cxl_decoder *cxld)
 {
 	int rc;
 
@@ -2658,6 +2768,9 @@ static struct cxl_region *__create_region(struct cxl_root_decoder *cxlrd,
 		return ERR_PTR(-EBUSY);
 	}
 
+	if (pmem_params)
+		return devm_cxl_pmem_add_region(cxlrd, id, pmem_params, cxld,
+						CXL_DECODER_HOSTONLYMEM);
 	return devm_cxl_add_region(cxlrd, id, mode, CXL_DECODER_HOSTONLYMEM);
 }
 
@@ -2672,7 +2785,7 @@ static ssize_t create_region_store(struct device *dev, const char *buf,
 	if (rc != 1)
 		return -EINVAL;
 
-	cxlr = __create_region(cxlrd, mode, id);
+	cxlr = cxl_create_region(cxlrd, mode, id, NULL, NULL);
 	if (IS_ERR(cxlr))
 		return PTR_ERR(cxlr);
 
@@ -3641,8 +3754,9 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
 	struct cxl_region *cxlr;
 
 	do {
-		cxlr = __create_region(cxlrd, cxlds->part[part].mode,
-				       atomic_read(&cxlrd->region_id));
+		cxlr = cxl_create_region(cxlrd, cxlds->part[part].mode,
+					 atomic_read(&cxlrd->region_id),
+					 NULL, NULL);
 	} while (IS_ERR(cxlr) && PTR_ERR(cxlr) == -EBUSY);
 
 	if (IS_ERR(cxlr)) {
-- 
2.34.1

On Wed, 19 Nov 2025 13:22:49 +0530
Neeraj Kumar <s.neeraj@samsung.com> wrote:

> devm_cxl_pmem_add_region() is used to create cxl region based on region
> information scanned from LSA.
> 
> devm_cxl_add_region() is used to just allocate cxlr and its fields are
> filled later by userspace tool using device attributes (*_store()).
> 
> Inspiration for devm_cxl_pmem_add_region() is taken from these device
> attributes (_store*) calls. It allocates cxlr and fills information
> parsed from LSA and calls device_add(&cxlr->dev) to initiate further
> region creation porbes
> 
> Rename __create_region() to cxl_create_region(), which will be used
> in later patch to create cxl region after fetching region information
> from LSA.
> 
> Signed-off-by: Neeraj Kumar <s.neeraj@samsung.com>

I think there is an underflow of the device reference count in an error
path. See below.  

Jonathan

> +static struct cxl_region *
> +devm_cxl_pmem_add_region(struct cxl_root_decoder *cxlrd, int id,
> +			 struct cxl_pmem_region_params *params,
> +			 struct cxl_decoder *cxld,
> +			 enum cxl_decoder_type type)
> +{
> +	struct cxl_endpoint_decoder *cxled;
> +	struct cxl_region_params *p;
> +	struct cxl_port *root_port;
> +	struct device *dev;
> +	int rc;
> +
> +	struct cxl_region *cxlr __free(put_cxl_region) =
> +		cxl_region_alloc(cxlrd, id);
It can be tricky to get the use of __free() when related
to devices that are being registered right.  I'm not sure it
is quite correct here.

> +	if (IS_ERR(cxlr))
> +		return cxlr;
> +
> +	cxlr->mode = CXL_PARTMODE_PMEM;
> +	cxlr->type = type;
> +
> +	dev = &cxlr->dev;
> +	rc = dev_set_name(dev, "region%d", id);
> +	if (rc)
> +		return ERR_PTR(rc);
> +
> +	p = &cxlr->params;
> +	p->uuid = params->uuid;
> +	p->interleave_ways = params->nlabel;
> +	p->interleave_granularity = params->ig;
> +
> +	rc = alloc_region_hpa(cxlr, params->rawsize);
> +	if (rc)
> +		return ERR_PTR(rc);
> +
> +	cxled = to_cxl_endpoint_decoder(&cxld->dev);
> +
> +	rc = cxl_dpa_set_part(cxled, CXL_PARTMODE_PMEM);
> +	if (rc)
> +		return ERR_PTR(rc);
> +
> +	rc = alloc_region_dpa(cxled, params->rawsize);
> +	if (rc)
> +		return ERR_PTR(rc);
> +
> +	/*
> +	 * TODO: Currently we have support of interleave_way == 1, where
> +	 * we can only have one region per mem device. It means mem device
> +	 * position (params->position) will always be 0. It is therefore
> +	 * attaching only one target at params->position
> +	 */
> +	if (params->position)
> +		return ERR_PTR(-EOPNOTSUPP);
> +
> +	rc = attach_target(cxlr, cxled, params->position, TASK_INTERRUPTIBLE);
> +	if (rc)
> +		return ERR_PTR(rc);
> +
> +	rc = __commit(cxlr);
> +	if (rc)
> +		return ERR_PTR(rc);
> +
> +	rc = device_add(dev);
> +	if (rc)
> +		return ERR_PTR(rc);
> +
> +	root_port = to_cxl_port(cxlrd->cxlsd.cxld.dev.parent);
> +	rc = devm_add_action_or_reset(root_port->uport_dev,
> +			unregister_region, cxlr);
> +	if (rc)
In this path the __free(put_cxl_region) will put once.
The unregister_region will both unregister and put.  The
dev_add_action_or_reset() will have called unregister_region()
Which does both device_del() and a put on cxlr->dev. 

I might have missed another reference but at first glance at least
this underflows.

Note the different error path for the devm_add_action_or_reset
in current devm_cxl_add_region() which is there because there isn't
another reference count to decrement.

Various ways to solve this.  A common one is to separate the
allocation and adding stuff into another function (with __free as
you have here) and call that from here, leaving this outer wrapper
just doing the devm_add_action_or_reset() if everything else
has succeeded and hence no need for the outer function to do any
other reference coutn handling.  Or just don't use __free() as
is done in devm_cxl_add_region()


> +		return ERR_PTR(rc);
> +
> +	dev_dbg(root_port->uport_dev, "%s: created %s\n",
> +		dev_name(&cxlrd->cxlsd.cxld.dev), dev_name(dev));
> +
> +	return no_free_ptr(cxlr);
> +}

On 17/12/25 03:28PM, Jonathan Cameron wrote:
>On Wed, 19 Nov 2025 13:22:49 +0530
>Neeraj Kumar <s.neeraj@samsung.com> wrote:
>
>> devm_cxl_pmem_add_region() is used to create cxl region based on region
>> information scanned from LSA.
>>
>> devm_cxl_add_region() is used to just allocate cxlr and its fields are
>> filled later by userspace tool using device attributes (*_store()).
>>
>> Inspiration for devm_cxl_pmem_add_region() is taken from these device
>> attributes (_store*) calls. It allocates cxlr and fills information
>> parsed from LSA and calls device_add(&cxlr->dev) to initiate further
>> region creation porbes
>>
>> Rename __create_region() to cxl_create_region(), which will be used
>> in later patch to create cxl region after fetching region information
>> from LSA.
>>
>> Signed-off-by: Neeraj Kumar <s.neeraj@samsung.com>
>
>I think there is an underflow of the device reference count in an error
>path. See below.
>
>Jonathan
>
>> +static struct cxl_region *
>> +devm_cxl_pmem_add_region(struct cxl_root_decoder *cxlrd, int id,
>> +			 struct cxl_pmem_region_params *params,
>> +			 struct cxl_decoder *cxld,
>> +			 enum cxl_decoder_type type)
>> +{
>> +	struct cxl_endpoint_decoder *cxled;
>> +	struct cxl_region_params *p;
>> +	struct cxl_port *root_port;
>> +	struct device *dev;
>> +	int rc;
>> +
>> +	struct cxl_region *cxlr __free(put_cxl_region) =
>> +		cxl_region_alloc(cxlrd, id);
>It can be tricky to get the use of __free() when related
>to devices that are being registered right.  I'm not sure it
>is quite correct here.
>
>> +	if (IS_ERR(cxlr))
>> +		return cxlr;
>> +
>> +	cxlr->mode = CXL_PARTMODE_PMEM;
>> +	cxlr->type = type;
>> +
>> +	dev = &cxlr->dev;
>> +	rc = dev_set_name(dev, "region%d", id);
>> +	if (rc)
>> +		return ERR_PTR(rc);
>> +
>> +	p = &cxlr->params;
>> +	p->uuid = params->uuid;
>> +	p->interleave_ways = params->nlabel;
>> +	p->interleave_granularity = params->ig;
>> +
>> +	rc = alloc_region_hpa(cxlr, params->rawsize);
>> +	if (rc)
>> +		return ERR_PTR(rc);
>> +
>> +	cxled = to_cxl_endpoint_decoder(&cxld->dev);
>> +
>> +	rc = cxl_dpa_set_part(cxled, CXL_PARTMODE_PMEM);
>> +	if (rc)
>> +		return ERR_PTR(rc);
>> +
>> +	rc = alloc_region_dpa(cxled, params->rawsize);
>> +	if (rc)
>> +		return ERR_PTR(rc);
>> +
>> +	/*
>> +	 * TODO: Currently we have support of interleave_way == 1, where
>> +	 * we can only have one region per mem device. It means mem device
>> +	 * position (params->position) will always be 0. It is therefore
>> +	 * attaching only one target at params->position
>> +	 */
>> +	if (params->position)
>> +		return ERR_PTR(-EOPNOTSUPP);
>> +
>> +	rc = attach_target(cxlr, cxled, params->position, TASK_INTERRUPTIBLE);
>> +	if (rc)
>> +		return ERR_PTR(rc);
>> +
>> +	rc = __commit(cxlr);
>> +	if (rc)
>> +		return ERR_PTR(rc);
>> +
>> +	rc = device_add(dev);
>> +	if (rc)
>> +		return ERR_PTR(rc);
>> +
>> +	root_port = to_cxl_port(cxlrd->cxlsd.cxld.dev.parent);
>> +	rc = devm_add_action_or_reset(root_port->uport_dev,
>> +			unregister_region, cxlr);
>> +	if (rc)
>In this path the __free(put_cxl_region) will put once.
>The unregister_region will both unregister and put.  The
>dev_add_action_or_reset() will have called unregister_region()
>Which does both device_del() and a put on cxlr->dev.
>
>I might have missed another reference but at first glance at least
>this underflows.
>
>Note the different error path for the devm_add_action_or_reset
>in current devm_cxl_add_region() which is there because there isn't
>another reference count to decrement.
>
>Various ways to solve this.  A common one is to separate the
>allocation and adding stuff into another function (with __free as
>you have here) and call that from here, leaving this outer wrapper
>just doing the devm_add_action_or_reset() if everything else
>has succeeded and hence no need for the outer function to do any
>other reference coutn handling.  Or just don't use __free() as
>is done in devm_cxl_add_region()
>

I have used __free() based on Dave's review comment in V2[1] to
avoid extra gotos. Thanks for catching this reference underflow.

I have fixed it in V5 as per your suggestion.
I have used separate routine cxl_pmem_region_prep() where i have used __free().

[1]: https://lore.kernel.org/linux-cxl/148912029.181757055784505.JavaMail.epsvc@epcpadp2new/



Regards,
Neeraj

On 11/19/25 12:52 AM, Neeraj Kumar wrote:
> devm_cxl_pmem_add_region() is used to create cxl region based on region
> information scanned from LSA.
> 
> devm_cxl_add_region() is used to just allocate cxlr and its fields are
> filled later by userspace tool using device attributes (*_store()).
> 
> Inspiration for devm_cxl_pmem_add_region() is taken from these device
> attributes (_store*) calls. It allocates cxlr and fills information
> parsed from LSA and calls device_add(&cxlr->dev) to initiate further
> region creation porbes
> 
> Rename __create_region() to cxl_create_region(), which will be used
> in later patch to create cxl region after fetching region information
> from LSA.
> 
> Signed-off-by: Neeraj Kumar <s.neeraj@samsung.com>

small comment below, otherwise
Reviewed-by: Dave Jiang <dave.jiang@intel.com>

> ---
>  drivers/cxl/core/core.h   |  12 ++++
>  drivers/cxl/core/region.c | 124 ++++++++++++++++++++++++++++++++++++--
>  2 files changed, 131 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
> index 1fb66132b777..fde96507cb75 100644
> --- a/drivers/cxl/core/core.h
> +++ b/drivers/cxl/core/core.h
> @@ -42,6 +42,10 @@ int cxl_get_poison_by_endpoint(struct cxl_port *port);
>  struct cxl_region *cxl_dpa_to_region(const struct cxl_memdev *cxlmd, u64 dpa);
>  u64 cxl_dpa_to_hpa(struct cxl_region *cxlr, const struct cxl_memdev *cxlmd,
>  		   u64 dpa);
> +struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
> +				     enum cxl_partition_mode mode, int id,
> +				     struct cxl_pmem_region_params *params,
> +				     struct cxl_decoder *cxld);
>  
>  #else
>  static inline u64 cxl_dpa_to_hpa(struct cxl_region *cxlr,
> @@ -71,6 +75,14 @@ static inline int cxl_region_init(void)
>  static inline void cxl_region_exit(void)
>  {
>  }
> +static inline struct cxl_region *
> +cxl_create_region(struct cxl_root_decoder *cxlrd,
> +		  enum cxl_partition_mode mode, int id,
> +		  struct cxl_pmem_region_params *params,
> +		  struct cxl_decoder *cxld)
> +{
> +	return ERR_PTR(-EOPNOTSUPP);
> +}
>  #define CXL_REGION_ATTR(x) NULL
>  #define CXL_REGION_TYPE(x) NULL
>  #define SET_CXL_REGION_ATTR(x)
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index 3c868c4de4ec..06a75f0a8e9b 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -2618,6 +2618,114 @@ static struct cxl_region *devm_cxl_add_region(struct cxl_root_decoder *cxlrd,
>  	return ERR_PTR(rc);
>  }
>  
> +static ssize_t alloc_region_hpa(struct cxl_region *cxlr, u64 size)
> +{
> +	int rc;
> +
> +	ACQUIRE(rwsem_write_kill, rwsem)(&cxl_rwsem.region);
> +	if ((rc = ACQUIRE_ERR(rwsem_write_kill, &rwsem)))
> +		return rc;
> +
> +	if (!size)
> +		return -EINVAL;

Why not do this check before acquiring the lock?

DJ

> +
> +	return alloc_hpa(cxlr, size);
> +}
> +
> +static ssize_t alloc_region_dpa(struct cxl_endpoint_decoder *cxled, u64 size)
> +{
> +	int rc;
> +
> +	if (!size)
> +		return -EINVAL;
> +
> +	if (!IS_ALIGNED(size, SZ_256M))
> +		return -EINVAL;
> +
> +	rc = cxl_dpa_free(cxled);
> +	if (rc)
> +		return rc;
> +
> +	return cxl_dpa_alloc(cxled, size);
> +}
> +
> +static struct cxl_region *
> +devm_cxl_pmem_add_region(struct cxl_root_decoder *cxlrd, int id,
> +			 struct cxl_pmem_region_params *params,
> +			 struct cxl_decoder *cxld,
> +			 enum cxl_decoder_type type)
> +{
> +	struct cxl_endpoint_decoder *cxled;
> +	struct cxl_region_params *p;
> +	struct cxl_port *root_port;
> +	struct device *dev;
> +	int rc;
> +
> +	struct cxl_region *cxlr __free(put_cxl_region) =
> +		cxl_region_alloc(cxlrd, id);
> +	if (IS_ERR(cxlr))
> +		return cxlr;
> +
> +	cxlr->mode = CXL_PARTMODE_PMEM;
> +	cxlr->type = type;
> +
> +	dev = &cxlr->dev;
> +	rc = dev_set_name(dev, "region%d", id);
> +	if (rc)
> +		return ERR_PTR(rc);
> +
> +	p = &cxlr->params;
> +	p->uuid = params->uuid;
> +	p->interleave_ways = params->nlabel;
> +	p->interleave_granularity = params->ig;
> +
> +	rc = alloc_region_hpa(cxlr, params->rawsize);
> +	if (rc)
> +		return ERR_PTR(rc);
> +
> +	cxled = to_cxl_endpoint_decoder(&cxld->dev);
> +
> +	rc = cxl_dpa_set_part(cxled, CXL_PARTMODE_PMEM);
> +	if (rc)
> +		return ERR_PTR(rc);
> +
> +	rc = alloc_region_dpa(cxled, params->rawsize);
> +	if (rc)
> +		return ERR_PTR(rc);
> +
> +	/*
> +	 * TODO: Currently we have support of interleave_way == 1, where
> +	 * we can only have one region per mem device. It means mem device
> +	 * position (params->position) will always be 0. It is therefore
> +	 * attaching only one target at params->position
> +	 */
> +	if (params->position)
> +		return ERR_PTR(-EOPNOTSUPP);
> +
> +	rc = attach_target(cxlr, cxled, params->position, TASK_INTERRUPTIBLE);
> +	if (rc)
> +		return ERR_PTR(rc);
> +
> +	rc = __commit(cxlr);
> +	if (rc)
> +		return ERR_PTR(rc);
> +
> +	rc = device_add(dev);
> +	if (rc)
> +		return ERR_PTR(rc);
> +
> +	root_port = to_cxl_port(cxlrd->cxlsd.cxld.dev.parent);
> +	rc = devm_add_action_or_reset(root_port->uport_dev,
> +			unregister_region, cxlr);
> +	if (rc)
> +		return ERR_PTR(rc);
> +
> +	dev_dbg(root_port->uport_dev, "%s: created %s\n",
> +		dev_name(&cxlrd->cxlsd.cxld.dev), dev_name(dev));
> +
> +	return no_free_ptr(cxlr);
> +}
> +
>  static ssize_t __create_region_show(struct cxl_root_decoder *cxlrd, char *buf)
>  {
>  	return sysfs_emit(buf, "region%u\n", atomic_read(&cxlrd->region_id));
> @@ -2635,8 +2743,10 @@ static ssize_t create_ram_region_show(struct device *dev,
>  	return __create_region_show(to_cxl_root_decoder(dev), buf);
>  }
>  
> -static struct cxl_region *__create_region(struct cxl_root_decoder *cxlrd,
> -					  enum cxl_partition_mode mode, int id)
> +struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
> +				     enum cxl_partition_mode mode, int id,
> +				     struct cxl_pmem_region_params *pmem_params,
> +				     struct cxl_decoder *cxld)
>  {
>  	int rc;
>  
> @@ -2658,6 +2768,9 @@ static struct cxl_region *__create_region(struct cxl_root_decoder *cxlrd,
>  		return ERR_PTR(-EBUSY);
>  	}
>  
> +	if (pmem_params)
> +		return devm_cxl_pmem_add_region(cxlrd, id, pmem_params, cxld,
> +						CXL_DECODER_HOSTONLYMEM);
>  	return devm_cxl_add_region(cxlrd, id, mode, CXL_DECODER_HOSTONLYMEM);
>  }
>  
> @@ -2672,7 +2785,7 @@ static ssize_t create_region_store(struct device *dev, const char *buf,
>  	if (rc != 1)
>  		return -EINVAL;
>  
> -	cxlr = __create_region(cxlrd, mode, id);
> +	cxlr = cxl_create_region(cxlrd, mode, id, NULL, NULL);
>  	if (IS_ERR(cxlr))
>  		return PTR_ERR(cxlr);
>  
> @@ -3641,8 +3754,9 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
>  	struct cxl_region *cxlr;
>  
>  	do {
> -		cxlr = __create_region(cxlrd, cxlds->part[part].mode,
> -				       atomic_read(&cxlrd->region_id));
> +		cxlr = cxl_create_region(cxlrd, cxlds->part[part].mode,
> +					 atomic_read(&cxlrd->region_id),
> +					 NULL, NULL);
>  	} while (IS_ERR(cxlr) && PTR_ERR(cxlr) == -EBUSY);
>  
>  	if (IS_ERR(cxlr)) {

On 19/11/25 02:33PM, Dave Jiang wrote:
>
>
>On 11/19/25 12:52 AM, Neeraj Kumar wrote:
>> devm_cxl_pmem_add_region() is used to create cxl region based on region
>> information scanned from LSA.
>>
>> devm_cxl_add_region() is used to just allocate cxlr and its fields are
>> filled later by userspace tool using device attributes (*_store()).
>>
>> Inspiration for devm_cxl_pmem_add_region() is taken from these device
>> attributes (_store*) calls. It allocates cxlr and fills information
>> parsed from LSA and calls device_add(&cxlr->dev) to initiate further
>> region creation porbes
>>
>> Rename __create_region() to cxl_create_region(), which will be used
>> in later patch to create cxl region after fetching region information
>> from LSA.
>>
>> Signed-off-by: Neeraj Kumar <s.neeraj@samsung.com>
>
>small comment below, otherwise
>Reviewed-by: Dave Jiang <dave.jiang@intel.com>

Thanks Dave for RB tag.

>
>> ---
>>  drivers/cxl/core/core.h   |  12 ++++
>>  drivers/cxl/core/region.c | 124 ++++++++++++++++++++++++++++++++++++--
>>  2 files changed, 131 insertions(+), 5 deletions(-)
>>
>> --- a/drivers/cxl/core/region.c
>> +++ b/drivers/cxl/core/region.c
>>
>> +static ssize_t alloc_region_hpa(struct cxl_region *cxlr, u64 size)
>> +{
>> +	int rc;
>> +
>> +	ACQUIRE(rwsem_write_kill, rwsem)(&cxl_rwsem.region);
>> +	if ((rc = ACQUIRE_ERR(rwsem_write_kill, &rwsem)))
>> +		return rc;
>> +
>> +	if (!size)
>> +		return -EINVAL;
>
>Why not do this check before acquiring the lock?
>
>DJ

Fixed it in V5.


Regards,
Neeraj