netdev - [PATCH v18 14/20] cxl/region: Factor out interleave ways setup

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Message-ID: <20250918091746.2034285-15-alejandro.lucero-palau@amd.com>
Date: Thu, 18 Sep 2025 10:17:40 +0100
From: <alejandro.lucero-palau@....com>
To: <linux-cxl@...r.kernel.org>, <netdev@...r.kernel.org>,
	<dan.j.williams@...el.com>, <edward.cree@....com>, <davem@...emloft.net>,
	<kuba@...nel.org>, <pabeni@...hat.com>, <edumazet@...gle.com>,
	<dave.jiang@...el.com>
CC: Alejandro Lucero <alucerop@....com>, Zhi Wang <zhiw@...dia.com>, "Jonathan
 Cameron" <Jonathan.Cameron@...wei.com>, Ben Cheatham
	<benjamin.cheatham@....com>, Alison Schofield <alison.schofield@...el.com>
Subject: [PATCH v18 14/20] cxl/region: Factor out interleave ways setup

From: Alejandro Lucero <alucerop@....com>

Region creation based on Type3 devices is triggered from user space
allowing memory combination through interleaving.

In preparation for kernel driven region creation, that is Type2 drivers
triggering region creation backed with its advertised CXL memory, factor
out a common helper from the user-sysfs region setup for interleave ways.

Signed-off-by: Alejandro Lucero <alucerop@....com>
Reviewed-by: Zhi Wang <zhiw@...dia.com>
Reviewed-by: Dave Jiang <dave.jiang@...el.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Reviewed-by: Ben Cheatham <benjamin.cheatham@....com>
Reviewed-by: Alison Schofield <alison.schofield@...el.com>
---
 drivers/cxl/core/region.c | 43 ++++++++++++++++++++++++---------------
 1 file changed, 27 insertions(+), 16 deletions(-)

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 3c65ffd17a98..6ea74f53936a 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -483,22 +483,14 @@ static ssize_t interleave_ways_show(struct device *dev,
 
 static const struct attribute_group *get_cxl_region_target_group(void);
 
-static ssize_t interleave_ways_store(struct device *dev,
-				     struct device_attribute *attr,
-				     const char *buf, size_t len)
+static int set_interleave_ways(struct cxl_region *cxlr, int val)
 {
-	struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(dev->parent);
+	struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(cxlr->dev.parent);
 	struct cxl_decoder *cxld = &cxlrd->cxlsd.cxld;
-	struct cxl_region *cxlr = to_cxl_region(dev);
 	struct cxl_region_params *p = &cxlr->params;
-	unsigned int val, save;
-	int rc;
+	int save, rc;
 	u8 iw;
 
-	rc = kstrtouint(buf, 0, &val);
-	if (rc)
-		return rc;
-
 	rc = ways_to_eiw(val, &iw);
 	if (rc)
 		return rc;
@@ -513,9 +505,7 @@ static ssize_t interleave_ways_store(struct device *dev,
 		return -EINVAL;
 	}
 
-	ACQUIRE(rwsem_write_kill, rwsem)(&cxl_rwsem.region);
-	if ((rc = ACQUIRE_ERR(rwsem_write_kill, &rwsem)))
-		return rc;
+	lockdep_assert_held_write(&cxl_rwsem.region);
 
 	if (p->state >= CXL_CONFIG_INTERLEAVE_ACTIVE)
 		return -EBUSY;
@@ -523,10 +513,31 @@ static ssize_t interleave_ways_store(struct device *dev,
 	save = p->interleave_ways;
 	p->interleave_ways = val;
 	rc = sysfs_update_group(&cxlr->dev.kobj, get_cxl_region_target_group());
-	if (rc) {
+	if (rc)
 		p->interleave_ways = save;
+
+	return rc;
+}
+
+static ssize_t interleave_ways_store(struct device *dev,
+				     struct device_attribute *attr,
+				     const char *buf, size_t len)
+{
+	struct cxl_region *cxlr = to_cxl_region(dev);
+	unsigned int val;
+	int rc;
+
+	rc = kstrtouint(buf, 0, &val);
+	if (rc)
+		return rc;
+
+	ACQUIRE(rwsem_write_kill, rwsem)(&cxl_rwsem.region);
+	if ((rc = ACQUIRE_ERR(rwsem_write_kill, &rwsem)))
+		return rc;
+
+	rc = set_interleave_ways(cxlr, val);
+	if (rc)
 		return rc;
-	}
 
 	return len;
 }
-- 
2.34.1