linux-kernel - [RFC PATCH 20/20] cxl/pmem_region: Add cxl region label updation and deletion device attributes

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Message-Id: <1371006431.81750165382853.JavaMail.epsvc@epcpadp2new>
Date: Tue, 17 Jun 2025 18:09:44 +0530
From: Neeraj Kumar <s.neeraj@...sung.com>
To: dan.j.williams@...el.com, dave@...olabs.net,
	jonathan.cameron@...wei.com, dave.jiang@...el.com,
	alison.schofield@...el.com, vishal.l.verma@...el.com, ira.weiny@...el.com
Cc: a.manzanares@...sung.com, nifan.cxl@...il.com, anisa.su@...sung.com,
	vishak.g@...sung.com, krish.reddy@...sung.com, arun.george@...sung.com,
	alok.rathore@...sung.com, s.neeraj@...sung.com, neeraj.kernel@...il.com,
	linux-kernel@...r.kernel.org, linux-cxl@...r.kernel.org,
	nvdimm@...ts.linux.dev, gost.dev@...sung.com, cpgs@...sung.com
Subject: [RFC PATCH 20/20] cxl/pmem_region: Add cxl region label updation
 and deletion device attributes

Using these attributes region label is added/deleted into LSA. These
attributes are called from userspace (ndctl) after region creation.

Signed-off-by: Neeraj Kumar <s.neeraj@...sung.com>
---
 drivers/cxl/core/pmem_region.c | 103 +++++++++++++++++++++++++++++++++
 drivers/cxl/cxl.h              |   1 +
 2 files changed, 104 insertions(+)

diff --git a/drivers/cxl/core/pmem_region.c b/drivers/cxl/core/pmem_region.c
index a29526c27d40..f582d796c21b 100644
--- a/drivers/cxl/core/pmem_region.c
+++ b/drivers/cxl/core/pmem_region.c
@@ -45,8 +45,111 @@ static void cxl_pmem_region_release(struct device *dev)
 	kfree(cxlr_pmem);
 }
 
+static ssize_t region_label_update_store(struct device *dev,
+					 struct device_attribute *attr,
+					 const char *buf, size_t len)
+{
+	struct cxl_pmem_region *cxlr_pmem = to_cxl_pmem_region(dev);
+	struct cxl_region *cxlr = cxlr_pmem->cxlr;
+	struct cxl_region_params *p = &cxlr->params;
+	ssize_t rc;
+	bool update;
+
+	rc = kstrtobool(buf, &update);
+	if (rc)
+		return rc;
+
+	rc = down_write_killable(&cxl_region_rwsem);
+	if (rc)
+		return rc;
+
+	/* Region not yet committed */
+	if (update && p->state != CXL_CONFIG_COMMIT) {
+		dev_dbg(dev, "region not committed, can't update into LSA\n");
+		rc = -ENXIO;
+		goto out;
+	}
+
+	if (cxlr && cxlr->cxlr_pmem && cxlr->cxlr_pmem->nd_region) {
+		rc = nd_region_label_update(cxlr->cxlr_pmem->nd_region);
+
+		if (!rc)
+			p->region_label_state = 1;
+	}
+
+out:
+	up_write(&cxl_region_rwsem);
+
+	if (rc)
+		return rc;
+
+	return len;
+}
+
+static ssize_t region_label_update_show(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct cxl_pmem_region *cxlr_pmem = to_cxl_pmem_region(dev);
+	struct cxl_region *cxlr = cxlr_pmem->cxlr;
+	struct cxl_region_params *p = &cxlr->params;
+	ssize_t rc;
+
+	rc = down_read_interruptible(&cxl_region_rwsem);
+	if (rc)
+		return rc;
+	rc = sysfs_emit(buf, "%d\n", p->region_label_state);
+	up_read(&cxl_region_rwsem);
+
+	return rc;
+}
+static DEVICE_ATTR_RW(region_label_update);
+
+static ssize_t region_label_delete_store(struct device *dev,
+				   struct device_attribute *attr,
+				   const char *buf, size_t len)
+{
+	struct cxl_pmem_region *cxlr_pmem = to_cxl_pmem_region(dev);
+	struct cxl_region *cxlr = cxlr_pmem->cxlr;
+	struct cxl_region_params *p = &cxlr->params;
+	ssize_t rc;
+
+	rc = down_write_killable(&cxl_region_rwsem);
+	if (rc)
+		return rc;
+
+	if (cxlr && cxlr->cxlr_pmem && cxlr->cxlr_pmem->nd_region) {
+		rc = nd_region_label_delete(cxlr->cxlr_pmem->nd_region);
+		if (rc)
+			goto out;
+	}
+
+	if (!rc)
+		p->region_label_state = 0;
+
+out:
+	up_write(&cxl_region_rwsem);
+
+	if (rc)
+		return rc;
+
+	return len;
+}
+DEVICE_ATTR_WO(region_label_delete);
+
+static struct attribute *cxl_pmem_region_attrs[] = {
+	&dev_attr_region_label_update.attr,
+	&dev_attr_region_label_delete.attr,
+	NULL,
+};
+
+struct attribute_group cxl_pmem_region_group = {
+	.attrs = cxl_pmem_region_attrs,
+};
+
 static const struct attribute_group *cxl_pmem_region_attribute_groups[] = {
 	&cxl_base_attribute_group,
+	&cxl_pmem_region_group,
 	NULL,
 };
 
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index c6cd0c8d78a1..f67bf7df287a 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -498,6 +498,7 @@ enum cxl_config_state {
  */
 struct cxl_region_params {
 	enum cxl_config_state state;
+	int region_label_state;
 	uuid_t uuid;
 	int interleave_ways;
 	int interleave_granularity;
-- 
2.34.1