[v1,07/29] cxl/region: Factor out code to find a root decoder's region

Commit Message

Robert Richter Jan. 7, 2025, 2:09 p.m. UTC

In function cxl_add_to_region() there is code to determine a root
decoder's region. Factor that code out. This is in preparation to
further rework and simplify function cxl_add_to_region().

No functional changes.

Signed-off-by: Robert Richter <[e-mail]>
---
 drivers/cxl/core/region.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

Comments

Gregory Price Jan. 7, 2025, 4:59 p.m. UTC | #1

On Tue, Jan 07, 2025 at 03:09:53PM +0100, Robert Richter wrote:
> In function cxl_add_to_region() there is code to determine a root
> decoder's region. Factor that code out. This is in preparation to
> further rework and simplify function cxl_add_to_region().
> 
> No functional changes.
> 
> Signed-off-by: Robert Richter <[e-mail]>
> ---
>  drivers/cxl/core/region.c | 24 ++++++++++++++++--------
>  1 file changed, 16 insertions(+), 8 deletions(-)
> 
... snip ...
>  	 * one does the construction and the others add to that.
>  	 */
>  	mutex_lock(&cxlrd->range_lock);

If the function must be called with the cxlrd range lock held, then the
function should have a comment/contract that states this.

> -	region_dev = device_find_child(&cxlrd->cxlsd.cxld.dev, hpa,
> -				       match_region_by_range);
> -	if (!region_dev) {
> +	cxlr = cxl_find_region_by_range(cxlrd, hpa);
> +	if (!cxlr)
>  		cxlr = construct_region(cxlrd, cxled);
> -		region_dev = &cxlr->dev;
> -	} else
> -		cxlr = to_cxl_region(region_dev);
>  	mutex_unlock(&cxlrd->range_lock);
>

Patch

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 448408918def..d5dcc94df0a5 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -3255,6 +3255,19 @@  static int match_region_by_range(struct device *dev, void *data)
 	return rc;
 }
 
+static struct cxl_region *
+cxl_find_region_by_range(struct cxl_root_decoder *cxlrd, struct range *hpa)
+{
+	struct device *region_dev;
+
+	region_dev = device_find_child(&cxlrd->cxlsd.cxld.dev, hpa,
+				       match_region_by_range);
+	if (!region_dev)
+		return NULL;
+
+	return to_cxl_region(region_dev);
+}
+
 /* Establish an empty region covering the given HPA range */
 static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
 					   struct cxl_endpoint_decoder *cxled)
@@ -3342,7 +3355,6 @@  static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
 int cxl_add_to_region(struct cxl_endpoint_decoder *cxled)
 {
 	struct range *hpa = &cxled->cxld.hpa_range;
-	struct device *region_dev;
 	struct cxl_root_decoder *cxlrd;
 	struct cxl_region_params *p;
 	struct cxl_region *cxlr;
@@ -3358,13 +3370,9 @@  int cxl_add_to_region(struct cxl_endpoint_decoder *cxled)
 	 * one does the construction and the others add to that.
 	 */
 	mutex_lock(&cxlrd->range_lock);
-	region_dev = device_find_child(&cxlrd->cxlsd.cxld.dev, hpa,
-				       match_region_by_range);
-	if (!region_dev) {
+	cxlr = cxl_find_region_by_range(cxlrd, hpa);
+	if (!cxlr)
 		cxlr = construct_region(cxlrd, cxled);
-		region_dev = &cxlr->dev;
-	} else
-		cxlr = to_cxl_region(region_dev);
 	mutex_unlock(&cxlrd->range_lock);
 
 	rc = PTR_ERR_OR_ZERO(cxlr);
@@ -3389,7 +3397,7 @@  int cxl_add_to_region(struct cxl_endpoint_decoder *cxled)
 				p->res);
 	}
 
-	put_device(region_dev);
+	put_device(&cxlr->dev);			/* cxl_find_region_by_range() */
 
 	return rc;
 }