On 7/30/25 5:12 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
>
> Renamed __create_region() to cxl_create_region() and make it an exported
> routine. This will be used in later patch to create cxl region after
> fetching region information from LSA.
>
> Also created some helper routines and refactored dpa_size_store(),
> commit_store() to avoid duplicate code usage in devm_cxl_pmem_add_region()
"Some helper routines are created to...."
I would drop the "Also"
>
> Signed-off-by: Neeraj Kumar <s.nee...@samsung.com>
> ---
> drivers/cxl/core/core.h | 1 +
> drivers/cxl/core/port.c | 29 ++++++----
> drivers/cxl/core/region.c | 118 +++++++++++++++++++++++++++++++++-----
> drivers/cxl/cxl.h | 12 ++++
> 4 files changed, 134 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
> index 2669f251d677..80c83e0117c6 100644
> --- a/drivers/cxl/core/core.h
> +++ b/drivers/cxl/core/core.h
> @@ -94,6 +94,7 @@ int cxl_dpa_free(struct cxl_endpoint_decoder *cxled);
> resource_size_t cxl_dpa_size(struct cxl_endpoint_decoder *cxled);
> resource_size_t cxl_dpa_resource_start(struct cxl_endpoint_decoder *cxled);
> bool cxl_resource_contains_addr(const struct resource *res, const
> resource_size_t addr);
> +ssize_t resize_or_free_dpa(struct cxl_endpoint_decoder *cxled, u64 size);
>
> enum cxl_rcrb {
> CXL_RCRB_DOWNSTREAM,
> diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
> index 29197376b18e..ba743e31f721 100644
> --- a/drivers/cxl/core/port.c
> +++ b/drivers/cxl/core/port.c
> @@ -243,16 +243,9 @@ static ssize_t dpa_size_show(struct device *dev, struct
> device_attribute *attr,
> return sysfs_emit(buf, "%pa\n", &size);
> }
>
> -static ssize_t dpa_size_store(struct device *dev, struct device_attribute
> *attr,
> - const char *buf, size_t len)
> +ssize_t resize_or_free_dpa(struct cxl_endpoint_decoder *cxled, u64 size)
Maybe it should be called cxl_realloc_dpa()? More comments later on...
> {
> - struct cxl_endpoint_decoder *cxled = to_cxl_endpoint_decoder(dev);
> - unsigned long long size;
> - ssize_t rc;
> -
> - rc = kstrtoull(buf, 0, &size);
> - if (rc)
> - return rc;
> + int rc;
>
> if (!IS_ALIGNED(size, SZ_256M))
> return -EINVAL;
> @@ -262,9 +255,23 @@ static ssize_t dpa_size_store(struct device *dev, struct
> device_attribute *attr,
> return rc;
>
> if (size == 0)
> - return len;
> + return 0;
> +
> + return cxl_dpa_alloc(cxled, size);
> +}
> +
> +static ssize_t dpa_size_store(struct device *dev, struct device_attribute
> *attr,
> + const char *buf, size_t len)
> +{
> + struct cxl_endpoint_decoder *cxled = to_cxl_endpoint_decoder(dev);
> + unsigned long long size;
> + ssize_t rc;
> +
> + rc = kstrtoull(buf, 0, &size);
> + if (rc)
> + return rc;
>
> - rc = cxl_dpa_alloc(cxled, size);
> + rc = resize_or_free_dpa(cxled, size);
> if (rc)
> return rc;
>
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index eef501f3384c..8578e046aa78 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -703,6 +703,23 @@ static int free_hpa(struct cxl_region *cxlr)
> return 0;
> }
>
> +static ssize_t resize_or_free_region_hpa(struct cxl_region *cxlr, u64 size)
> +{
> + int rc;
> +
> + ACQUIRE(rwsem_write_kill, rwsem)(&cxl_rwsem.region);
> + rc = ACQUIRE_ERR(rwsem_write_kill, &rwsem);
> + if (rc)
> + return rc;
> +
> + if (size)
> + rc = alloc_hpa(cxlr, size);
> + else
> + rc = free_hpa(cxlr);
> +
> + return rc;
> +}
I think it's better to have 2 helper functions rather a single ambiguous one
here. alloc_region_hpa() and free_region_hpa(). More on why later.
> +
> static ssize_t size_store(struct device *dev, struct device_attribute *attr,
> const char *buf, size_t len)
> {
> @@ -714,15 +731,7 @@ static ssize_t size_store(struct device *dev, struct
> device_attribute *attr,
> if (rc)
> return rc;
>
> - ACQUIRE(rwsem_write_kill, rwsem)(&cxl_rwsem.region);
> - if ((rc = ACQUIRE_ERR(rwsem_write_kill, &rwsem)))
> - return rc;
> -
> - if (val)
> - rc = alloc_hpa(cxlr, val);
> - else
> - rc = free_hpa(cxlr);
> -
> + rc = resize_or_free_region_hpa(cxlr, val);
> if (rc)
> return rc;
>
> @@ -2569,6 +2578,76 @@ static struct cxl_region *devm_cxl_add_region(struct
> cxl_root_decoder *cxlrd,
> return ERR_PTR(rc);
> }
>
> +static struct cxl_region *
> +devm_cxl_pmem_add_region(struct cxl_root_decoder *cxlrd,
> + int id,
> + enum cxl_partition_mode mode,
> + enum cxl_decoder_type type,
> + struct cxl_pmem_region_params *params,
> + struct cxl_decoder *cxld)
> +{
> + struct cxl_port *root_port;
> + struct cxl_region *cxlr;
> + struct cxl_endpoint_decoder *cxled;
> + struct cxl_region_params *p;
> + struct device *dev;
> + int rc;
> +
> + cxlr = cxl_region_alloc(cxlrd, id);
I think you can use __free() here to drop all the gotos.
struct cxl_region *cxlr __free(put_cxl_region) = cxl_region_alloc(cxlrd, id);
Just make sure to 'return no_free_ptr(cxlr)' at the successful end.
> + if (IS_ERR(cxlr))
> + return cxlr;
> + cxlr->mode = mode;
> + cxlr->type = type;
> +
> + dev = &cxlr->dev;
> + rc = dev_set_name(dev, "region%d", id);
> + if (rc)
> + goto err;
> +
> + p = &cxlr->params;
> + p->uuid = params->uuid;
> + p->interleave_ways = params->nlabel;
> + p->interleave_granularity = params->ig;
> +
> + if (resize_or_free_region_hpa(cxlr, params->rawsize))
> + goto err;
Given this is _add_region(), it really should only be calling
alloc_region_hpa() and not have to deal with free. Maybe a check before this
and make sure params->rawsize is not 0 is needed.
> +
> + cxled = to_cxl_endpoint_decoder(&cxld->dev);
> + if (resize_or_free_dpa(cxled, 0))
Given that resize_or_free_dpa() always frees, is this call necessary here?
> + goto err;
> +
> + if (cxl_dpa_set_part(cxled, CXL_PARTMODE_PMEM))
> + goto err;
> +
> + if (resize_or_free_dpa(cxled, params->rawsize))
Seems like it can be called once here instead and it'll just free and then
re-allocate whatever size in params->rawsize.
> + goto err;
> +
> + /* Attaching only one target due to interleave_way == 1 */
Is it missing a check of interleave_ways here? Also maybe additional comments
on why support iw==1 only?
> + if (attach_target(cxlr, cxled, params->position, TASK_INTERRUPTIBLE))
> + goto err;
> +
> + if (__commit(cxlr))
> + goto err;
> +
> + rc = device_add(dev);
> + if (rc)
> + goto err;
> +
> + 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 cxlr;
> +
> +err:
> + put_device(dev);
> + return ERR_PTR(rc);
> +}
> +
> 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));
> @@ -2586,8 +2665,10 @@ 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 *params,
Maybe name it pmem_params to avoid confusion with cxl region params.
> + struct cxl_decoder *cxld)
> {
> int rc;
>
> @@ -2609,8 +2690,14 @@ static struct cxl_region *__create_region(struct
> cxl_root_decoder *cxlrd,
> return ERR_PTR(-EBUSY);
> }
>
> - return devm_cxl_add_region(cxlrd, id, mode, CXL_DECODER_HOSTONLYMEM);
> + if (params)
> + return devm_cxl_pmem_add_region(cxlrd, id, mode,
> + CXL_DECODER_HOSTONLYMEM, params, cxld);
> + else
'else' not needed here. Just directly return.
> + return devm_cxl_add_region(cxlrd, id, mode,
> + CXL_DECODER_HOSTONLYMEM);
> }
> +EXPORT_SYMBOL_NS_GPL(cxl_create_region, "CXL");
>
> static ssize_t create_region_store(struct device *dev, const char *buf,
> size_t len, enum cxl_partition_mode mode)
> @@ -2623,7 +2710,7 @@ 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);
>
> @@ -3414,8 +3501,9 @@ 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)) {
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index 6edcec95e9ba..129db2e49aa7 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -865,6 +865,10 @@ int cxl_add_to_region(struct cxl_endpoint_decoder
> *cxled);
> struct cxl_dax_region *to_cxl_dax_region(struct device *dev);
> u64 cxl_port_get_spa_cache_alias(struct cxl_port *endpoint, u64 spa);
> void cxl_region_discovery(struct cxl_port *port);
> +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 bool is_cxl_pmem_region(struct device *dev)
> {
> @@ -890,6 +894,14 @@ static inline u64 cxl_port_get_spa_cache_alias(struct
> cxl_port *endpoint,
> static inline void cxl_region_discovery(struct cxl_port *port)
> {
> }
> +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 NULL;
return ERR_PTR(-EOPNOTSUPP);
> +}
> #endif
>
> void cxl_endpoint_parse_cdat(struct cxl_port *port);
