Re: [PATCH v3 08/18] cxl/region: Move find_cxl_root() to cxl_add_to_region()

[Dave Jiang <dave.jiang@intel.com>]

On 2/11/25 2:53 AM, Robert Richter wrote:
> When adding an endpoint to a region, the root port is determined
> first. Move this directly into cxl_add_to_region(). This is in
> preparation of the initialization of endpoints that iterates the port
> hierarchy from the endpoint up to the root port.
> 
> As a side-effect the root argument is removed from the argument lists
> of cxl_add_to_region() and related functions. Now, the endpoint is the
> only parameter to add a region. This simplifies the function
> interface.
> 
> Signed-off-by: Robert Richter <rrichter@amd.com>
> Reviewed-by: Gregory Price <gourry@gourry.net>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Tested-by: Gregory Price <gourry@gourry.net>

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> ---
>  drivers/cxl/core/region.c |  6 ++++--
>  drivers/cxl/cxl.h         |  6 ++----
>  drivers/cxl/port.c        | 15 +++------------
>  3 files changed, 9 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index b8201c2faa87..0e38bcb43be6 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -3312,9 +3312,11 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
>  	return ERR_PTR(rc);
>  }
>  
> -int cxl_add_to_region(struct cxl_port *root, struct cxl_endpoint_decoder *cxled)
> +int cxl_add_to_region(struct cxl_endpoint_decoder *cxled)
>  {
>  	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
> +	struct cxl_port *port = cxled_to_port(cxled);
> +	struct cxl_root *cxl_root __free(put_cxl_root) = find_cxl_root(port);
>  	struct range *hpa = &cxled->cxld.hpa_range;
>  	struct cxl_decoder *cxld = &cxled->cxld;
>  	struct device *cxlrd_dev, *region_dev;
> @@ -3324,7 +3326,7 @@ int cxl_add_to_region(struct cxl_port *root, struct cxl_endpoint_decoder *cxled)
>  	bool attach = false;
>  	int rc;
>  
> -	cxlrd_dev = device_find_child(&root->dev, &cxld->hpa_range,
> +	cxlrd_dev = device_find_child(&cxl_root->port.dev, &cxld->hpa_range,
>  				      match_root_decoder_by_range);
>  	if (!cxlrd_dev) {
>  		dev_err(cxlmd->dev.parent,
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index 0d7aff8b97b3..85dfc8df0a80 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -854,8 +854,7 @@ struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct cxl_port *port);
>  #ifdef CONFIG_CXL_REGION
>  bool is_cxl_pmem_region(struct device *dev);
>  struct cxl_pmem_region *to_cxl_pmem_region(struct device *dev);
> -int cxl_add_to_region(struct cxl_port *root,
> -		      struct cxl_endpoint_decoder *cxled);
> +int cxl_add_to_region(struct cxl_endpoint_decoder *cxled);
>  struct cxl_dax_region *to_cxl_dax_region(struct device *dev);
>  #else
>  static inline bool is_cxl_pmem_region(struct device *dev)
> @@ -866,8 +865,7 @@ static inline struct cxl_pmem_region *to_cxl_pmem_region(struct device *dev)
>  {
>  	return NULL;
>  }
> -static inline int cxl_add_to_region(struct cxl_port *root,
> -				    struct cxl_endpoint_decoder *cxled)
> +static inline int cxl_add_to_region(struct cxl_endpoint_decoder *cxled)
>  {
>  	return 0;
>  }
> diff --git a/drivers/cxl/port.c b/drivers/cxl/port.c
> index d2bfd1ff5492..74587a403e3d 100644
> --- a/drivers/cxl/port.c
> +++ b/drivers/cxl/port.c
> @@ -30,7 +30,7 @@ static void schedule_detach(void *cxlmd)
>  	schedule_cxl_memdev_detach(cxlmd);
>  }
>  
> -static int discover_region(struct device *dev, void *root)
> +static int discover_region(struct device *dev, void *unused)
>  {
>  	struct cxl_endpoint_decoder *cxled;
>  	int rc;
> @@ -49,7 +49,7 @@ static int discover_region(struct device *dev, void *root)
>  	 * Region enumeration is opportunistic, if this add-event fails,
>  	 * continue to the next endpoint decoder.
>  	 */
> -	rc = cxl_add_to_region(root, cxled);
> +	rc = cxl_add_to_region(cxled);
>  	if (rc)
>  		dev_dbg(dev, "failed to add to region: %#llx-%#llx\n",
>  			cxled->cxld.hpa_range.start, cxled->cxld.hpa_range.end);
> @@ -95,7 +95,6 @@ static int cxl_endpoint_port_probe(struct cxl_port *port)
>  	struct cxl_memdev *cxlmd = to_cxl_memdev(port->uport_dev);
>  	struct cxl_dev_state *cxlds = cxlmd->cxlds;
>  	struct cxl_hdm *cxlhdm;
> -	struct cxl_port *root;
>  	int rc;
>  
>  	rc = cxl_dvsec_rr_decode(cxlds, &info);
> @@ -126,19 +125,11 @@ static int cxl_endpoint_port_probe(struct cxl_port *port)
>  	if (rc)
>  		return rc;
>  
> -	/*
> -	 * This can't fail in practice as CXL root exit unregisters all
> -	 * descendant ports and that in turn synchronizes with cxl_port_probe()
> -	 */
> -	struct cxl_root *cxl_root __free(put_cxl_root) = find_cxl_root(port);
> -
> -	root = &cxl_root->port;
> -
>  	/*
>  	 * Now that all endpoint decoders are successfully enumerated, try to
>  	 * assemble regions from committed decoders
>  	 */
> -	device_for_each_child(&port->dev, root, discover_region);
> +	device_for_each_child(&port->dev, NULL, discover_region);
>  
>  	return 0;
>  }