linux-kernel - [PATCH v1 17/20] cxl/region: Remove create_region() call from construct

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Message-ID: <20250715191143.1023512-18-rrichter@amd.com>
Date: Tue, 15 Jul 2025 21:11:40 +0200
From: Robert Richter <rrichter@....com>
To: Alison Schofield <alison.schofield@...el.com>, Vishal Verma
	<vishal.l.verma@...el.com>, Ira Weiny <ira.weiny@...el.com>, Dan Williams
	<dan.j.williams@...el.com>, Jonathan Cameron <Jonathan.Cameron@...wei.com>,
	Dave Jiang <dave.jiang@...el.com>, Davidlohr Bueso <dave@...olabs.net>
CC: <linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Gregory Price
	<gourry@...rry.net>, "Fabio M. De Francesco"
	<fabio.m.de.francesco@...ux.intel.com>, Terry Bowman <terry.bowman@....com>,
	Robert Richter <rrichter@....com>
Subject: [PATCH v1 17/20] cxl/region: Remove create_region() call from construct_region()

To separate the creation and construction of a region, remove the
create_region() call from construct_region().

This makes the @cxled function argument in construct_region()
obsolete, remove it and instead start using @hpa_range of struct
cxl_region, which is initialized using the endpoint decoders hpa
range.

The region creation is moved to cxl_endpoint_get_region(). Use
put_device() to remove the created region if another region is found
for the same hpa range.

Signed-off-by: Robert Richter <rrichter@....com>
---
 drivers/cxl/core/region.c | 32 +++++++++++++++++---------------
 1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 7e21946072a5..a81278fbb0ab 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -3363,6 +3363,7 @@ static int cxl_extended_linear_cache_resize(struct cxl_region *cxlr,
 	return 0;
 }
 
+/* Establish a region for the endpoint decoder */
 static struct cxl_region *create_region(struct cxl_root_decoder *cxlrd,
 					struct cxl_endpoint_decoder *cxled)
 {
@@ -3407,23 +3408,17 @@ static struct cxl_region *create_region(struct cxl_root_decoder *cxlrd,
 	return cxlr;
 }
 
-/* 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)
+static struct cxl_region *construct_region(struct cxl_region *__cxlr)
 {
-	struct device *cxlrd_dev = &cxlrd->cxlsd.cxld.dev;
-	struct range *hpa = &cxled->cxld.hpa_range;
+	struct device *cxlrd_dev = &__cxlr->cxlrd->cxlsd.cxld.dev;
 	struct cxl_region_params *p;
+	struct range *hpa;
 	struct resource *res;
 	int rc;
 
 	struct cxl_region *cxlr __free(early_region_unregister) =
-		create_region(cxlrd, cxled);
-
-	if (IS_ERR(cxlr))
-		return cxlr;
+		devm_cxl_add_region(__cxlr, -1);
 
-	cxlr = devm_cxl_add_region(cxlr, -1);
 	if (IS_ERR(cxlr)) {
 		dev_err(cxlrd_dev->parent,
 			"%s: %s failed to add region: %ld\n",
@@ -3444,6 +3439,7 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
 	if (!res)
 		return ERR_PTR(-ENOMEM);
 
+	hpa = &cxlr->hpa_range;
 	*res = DEFINE_RES_MEM_NAMED(hpa->start, range_len(hpa),
 				    dev_name(&cxlr->dev));
 
@@ -3459,7 +3455,7 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
 			dev_name(&cxlr->dev), __func__, rc);
 	}
 
-	rc = insert_resource(cxlrd->res, res);
+	rc = insert_resource(cxlr->cxlrd->res, res);
 	if (rc) {
 		/*
 		 * Platform-firmware may not have split resources like "System
@@ -3491,7 +3487,7 @@ cxl_endpoint_get_region(struct cxl_endpoint_decoder *cxled)
 {
 	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
 	struct range *hpa = &cxled->cxld.hpa_range;
-	struct cxl_region *cxlr;
+	struct cxl_region *cxlr, *new;
 
 	struct cxl_root_decoder *cxlrd __free(put_cxl_root_decoder) =
 		cxl_find_root_decoder(cxled);
@@ -3504,15 +3500,21 @@ cxl_endpoint_get_region(struct cxl_endpoint_decoder *cxled)
 		return ERR_PTR(-ENXIO);
 	}
 
+	new = create_region(cxlrd, cxled);
+	if (IS_ERR(new))
+		return new;
+
 	/*
 	 * Ensure that if multiple threads race to construct_region() for @hpa
 	 * one does the construction and the others add to that.
 	 */
-	guard(mutex)(&cxlrd->range_lock);
+	guard(mutex)(&new->cxlrd->range_lock);
 
-	cxlr = cxl_find_region_by_range(cxlrd, hpa);
+	cxlr = cxl_find_region_by_range(new->cxlrd, &new->hpa_range);
 	if (!cxlr)
-		return construct_region(cxlrd, cxled);
+		return construct_region(new);
+
+	put_device(&new->dev);
 
 	return cxlr;
 }
-- 
2.39.5