core/region.c is overloaded with per-region control logic (pmem, dax,
sysram, etc). Move the pmem region driver logic from region.c into
region_pmem.c make it clear that this code only applies to pmem regions.

No functional changes.

Signed-off-by: Gregory Price <gourry@gourry.net>
---
 drivers/cxl/core/Makefile      |   1 +
 drivers/cxl/core/core.h        |   1 +
 drivers/cxl/core/region.c      | 184 --------------------------------
 drivers/cxl/core/region_pmem.c | 189 +++++++++++++++++++++++++++++++++
 4 files changed, 191 insertions(+), 184 deletions(-)
 create mode 100644 drivers/cxl/core/region_pmem.c

diff --git a/drivers/cxl/core/Makefile b/drivers/cxl/core/Makefile
index a639a9499972..d1484a0e5eb4 100644
--- a/drivers/cxl/core/Makefile
+++ b/drivers/cxl/core/Makefile
@@ -16,6 +16,7 @@ cxl_core-y += pmu.o
 cxl_core-y += cdat.o
 cxl_core-$(CONFIG_TRACING) += trace.o
 cxl_core-$(CONFIG_CXL_REGION) += region.o
+cxl_core-$(CONFIG_CXL_REGION) += region_pmem.o
 cxl_core-$(CONFIG_CXL_MCE) += mce.o
 cxl_core-$(CONFIG_CXL_FEATURES) += features.o
 cxl_core-$(CONFIG_CXL_EDAC_MEM_FEATURES) += edac.o
diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
index 5539e941782f..ef03966eeabd 100644
--- a/drivers/cxl/core/core.h
+++ b/drivers/cxl/core/core.h
@@ -50,6 +50,7 @@ int cxl_get_poison_by_endpoint(struct cxl_port *port);
 struct cxl_region *cxl_dpa_to_region(const struct cxl_memdev *cxlmd, u64 dpa);
 u64 cxl_dpa_to_hpa(struct cxl_region *cxlr, const struct cxl_memdev *cxlmd,
 		   u64 dpa);
+int devm_cxl_add_pmem_region(struct cxl_region *cxlr);
 
 #else
 static inline u64 cxl_dpa_to_hpa(struct cxl_region *cxlr,
diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index f24b7e754727..72aee1408efb 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -2781,46 +2781,6 @@ static ssize_t delete_region_store(struct device *dev,
 }
 DEVICE_ATTR_WO(delete_region);
 
-static void cxl_pmem_region_release(struct device *dev)
-{
-	struct cxl_pmem_region *cxlr_pmem = to_cxl_pmem_region(dev);
-	int i;
-
-	for (i = 0; i < cxlr_pmem->nr_mappings; i++) {
-		struct cxl_memdev *cxlmd = cxlr_pmem->mapping[i].cxlmd;
-
-		put_device(&cxlmd->dev);
-	}
-
-	kfree(cxlr_pmem);
-}
-
-static const struct attribute_group *cxl_pmem_region_attribute_groups[] = {
-	&cxl_base_attribute_group,
-	NULL,
-};
-
-const struct device_type cxl_pmem_region_type = {
-	.name = "cxl_pmem_region",
-	.release = cxl_pmem_region_release,
-	.groups = cxl_pmem_region_attribute_groups,
-};
-
-bool is_cxl_pmem_region(struct device *dev)
-{
-	return dev->type == &cxl_pmem_region_type;
-}
-EXPORT_SYMBOL_NS_GPL(is_cxl_pmem_region, "CXL");
-
-struct cxl_pmem_region *to_cxl_pmem_region(struct device *dev)
-{
-	if (dev_WARN_ONCE(dev, !is_cxl_pmem_region(dev),
-			  "not a cxl_pmem_region device\n"))
-		return NULL;
-	return container_of(dev, struct cxl_pmem_region, dev);
-}
-EXPORT_SYMBOL_NS_GPL(to_cxl_pmem_region, "CXL");
-
 struct cxl_poison_context {
 	struct cxl_port *port;
 	int part;
@@ -3476,64 +3436,6 @@ static int region_offset_to_dpa_result(struct cxl_region *cxlr, u64 offset,
 	return -ENXIO;
 }
 
-static struct lock_class_key cxl_pmem_region_key;
-
-static int cxl_pmem_region_alloc(struct cxl_region *cxlr)
-{
-	struct cxl_region_params *p = &cxlr->params;
-	struct cxl_nvdimm_bridge *cxl_nvb;
-	struct device *dev;
-	int i;
-
-	guard(rwsem_read)(&cxl_rwsem.region);
-	if (p->state != CXL_CONFIG_COMMIT)
-		return -ENXIO;
-
-	struct cxl_pmem_region *cxlr_pmem __free(kfree) =
-		kzalloc_flex(*cxlr_pmem, mapping, p->nr_targets);
-	if (!cxlr_pmem)
-		return -ENOMEM;
-
-	cxlr_pmem->hpa_range.start = p->res->start;
-	cxlr_pmem->hpa_range.end = p->res->end;
-
-	/* Snapshot the region configuration underneath the cxl_rwsem.region */
-	cxlr_pmem->nr_mappings = p->nr_targets;
-	for (i = 0; i < p->nr_targets; i++) {
-		struct cxl_endpoint_decoder *cxled = p->targets[i];
-		struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
-		struct cxl_pmem_region_mapping *m = &cxlr_pmem->mapping[i];
-
-		/*
-		 * Regions never span CXL root devices, so by definition the
-		 * bridge for one device is the same for all.
-		 */
-		if (i == 0) {
-			cxl_nvb = cxl_find_nvdimm_bridge(cxlmd->endpoint);
-			if (!cxl_nvb)
-				return -ENODEV;
-			cxlr->cxl_nvb = cxl_nvb;
-		}
-		m->cxlmd = cxlmd;
-		get_device(&cxlmd->dev);
-		m->start = cxled->dpa_res->start;
-		m->size = resource_size(cxled->dpa_res);
-		m->position = i;
-	}
-
-	dev = &cxlr_pmem->dev;
-	device_initialize(dev);
-	lockdep_set_class(&dev->mutex, &cxl_pmem_region_key);
-	device_set_pm_not_required(dev);
-	dev->parent = &cxlr->dev;
-	dev->bus = &cxl_bus_type;
-	dev->type = &cxl_pmem_region_type;
-	cxlr_pmem->cxlr = cxlr;
-	cxlr->cxlr_pmem = no_free_ptr(cxlr_pmem);
-
-	return 0;
-}
-
 static void cxl_dax_region_release(struct device *dev)
 {
 	struct cxl_dax_region *cxlr_dax = to_cxl_dax_region(dev);
@@ -3597,92 +3499,6 @@ static struct cxl_dax_region *cxl_dax_region_alloc(struct cxl_region *cxlr)
 	return cxlr_dax;
 }
 
-static void cxlr_pmem_unregister(void *_cxlr_pmem)
-{
-	struct cxl_pmem_region *cxlr_pmem = _cxlr_pmem;
-	struct cxl_region *cxlr = cxlr_pmem->cxlr;
-	struct cxl_nvdimm_bridge *cxl_nvb = cxlr->cxl_nvb;
-
-	/*
-	 * Either the bridge is in ->remove() context under the device_lock(),
-	 * or cxlr_release_nvdimm() is cancelling the bridge's release action
-	 * for @cxlr_pmem and doing it itself (while manually holding the bridge
-	 * lock).
-	 */
-	device_lock_assert(&cxl_nvb->dev);
-	cxlr->cxlr_pmem = NULL;
-	cxlr_pmem->cxlr = NULL;
-	device_unregister(&cxlr_pmem->dev);
-}
-
-static void cxlr_release_nvdimm(void *_cxlr)
-{
-	struct cxl_region *cxlr = _cxlr;
-	struct cxl_nvdimm_bridge *cxl_nvb = cxlr->cxl_nvb;
-
-	scoped_guard(device, &cxl_nvb->dev) {
-		if (cxlr->cxlr_pmem)
-			devm_release_action(&cxl_nvb->dev, cxlr_pmem_unregister,
-					    cxlr->cxlr_pmem);
-	}
-	cxlr->cxl_nvb = NULL;
-	put_device(&cxl_nvb->dev);
-}
-
-/**
- * devm_cxl_add_pmem_region() - add a cxl_region-to-nd_region bridge
- * @cxlr: parent CXL region for this pmem region bridge device
- *
- * Return: 0 on success negative error code on failure.
- */
-static int devm_cxl_add_pmem_region(struct cxl_region *cxlr)
-{
-	struct cxl_pmem_region *cxlr_pmem;
-	struct cxl_nvdimm_bridge *cxl_nvb;
-	struct device *dev;
-	int rc;
-
-	rc = cxl_pmem_region_alloc(cxlr);
-	if (rc)
-		return rc;
-	cxlr_pmem = cxlr->cxlr_pmem;
-	cxl_nvb = cxlr->cxl_nvb;
-
-	dev = &cxlr_pmem->dev;
-	rc = dev_set_name(dev, "pmem_region%d", cxlr->id);
-	if (rc)
-		goto err;
-
-	rc = device_add(dev);
-	if (rc)
-		goto err;
-
-	dev_dbg(&cxlr->dev, "%s: register %s\n", dev_name(dev->parent),
-		dev_name(dev));
-
-	scoped_guard(device, &cxl_nvb->dev) {
-		if (cxl_nvb->dev.driver)
-			rc = devm_add_action_or_reset(&cxl_nvb->dev,
-						      cxlr_pmem_unregister,
-						      cxlr_pmem);
-		else
-			rc = -ENXIO;
-	}
-
-	if (rc)
-		goto err_bridge;
-
-	/* @cxlr carries a reference on @cxl_nvb until cxlr_release_nvdimm */
-	return devm_add_action_or_reset(&cxlr->dev, cxlr_release_nvdimm, cxlr);
-
-err:
-	put_device(dev);
-err_bridge:
-	put_device(&cxl_nvb->dev);
-	cxlr->cxl_nvb = NULL;
-	return rc;
-}
-
 static void cxlr_dax_unregister(void *_cxlr_dax)
 {
 	struct cxl_dax_region *cxlr_dax = _cxlr_dax;
diff --git a/drivers/cxl/core/region_pmem.c b/drivers/cxl/core/region_pmem.c
new file mode 100644
index 000000000000..138c373a5700
--- /dev/null
+++ b/drivers/cxl/core/region_pmem.c
@@ -0,0 +1,189 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright(c) 2022 Intel Corporation. All rights reserved. */
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <cxlmem.h>
+#include <cxl.h>
+#include "core.h"
+
+static void cxl_pmem_region_release(struct device *dev)
+{
+	struct cxl_pmem_region *cxlr_pmem = to_cxl_pmem_region(dev);
+	int i;
+
+	for (i = 0; i < cxlr_pmem->nr_mappings; i++) {
+		struct cxl_memdev *cxlmd = cxlr_pmem->mapping[i].cxlmd;
+
+		put_device(&cxlmd->dev);
+	}
+
+	kfree(cxlr_pmem);
+}
+
+static const struct attribute_group *cxl_pmem_region_attribute_groups[] = {
+	&cxl_base_attribute_group,
+	NULL
+};
+
+const struct device_type cxl_pmem_region_type = {
+	.name = "cxl_pmem_region",
+	.release = cxl_pmem_region_release,
+	.groups = cxl_pmem_region_attribute_groups,
+};
+bool is_cxl_pmem_region(struct device *dev)
+{
+	return dev->type == &cxl_pmem_region_type;
+}
+EXPORT_SYMBOL_NS_GPL(is_cxl_pmem_region, "CXL");
+
+struct cxl_pmem_region *to_cxl_pmem_region(struct device *dev)
+{
+	if (dev_WARN_ONCE(dev, !is_cxl_pmem_region(dev),
+				"not a cxl_pmem_region device\n"))
+		return NULL;
+	return container_of(dev, struct cxl_pmem_region, dev);
+}
+EXPORT_SYMBOL_NS_GPL(to_cxl_pmem_region, "CXL");
+static struct lock_class_key cxl_pmem_region_key;
+
+static int cxl_pmem_region_alloc(struct cxl_region *cxlr)
+{
+	struct cxl_region_params *p = &cxlr->params;
+	struct cxl_nvdimm_bridge *cxl_nvb;
+	struct device *dev;
+	int i;
+
+	guard(rwsem_read)(&cxl_rwsem.region);
+	if (p->state != CXL_CONFIG_COMMIT)
+		return -ENXIO;
+
+	struct cxl_pmem_region *cxlr_pmem __free(kfree) =
+		kzalloc_flex(*cxlr_pmem, mapping, p->nr_targets);
+	if (!cxlr_pmem)
+		return -ENOMEM;
+
+	cxlr_pmem->hpa_range.start = p->res->start;
+	cxlr_pmem->hpa_range.end = p->res->end;
+
+	/* Snapshot the region configuration underneath the cxl_rwsem.region */
+	cxlr_pmem->nr_mappings = p->nr_targets;
+	for (i = 0; i < p->nr_targets; i++) {
+		struct cxl_endpoint_decoder *cxled = p->targets[i];
+		struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
+		struct cxl_pmem_region_mapping *m = &cxlr_pmem->mapping[i];
+
+		/*
+		 * Regions never span CXL root devices, so by definition the
+		 * bridge for one device is the same for all.
+		 */
+		if (i == 0) {
+			cxl_nvb = cxl_find_nvdimm_bridge(cxlmd->endpoint);
+			if (!cxl_nvb)
+				return -ENODEV;
+			cxlr->cxl_nvb = cxl_nvb;
+		}
+		m->cxlmd = cxlmd;
+		get_device(&cxlmd->dev);
+		m->start = cxled->dpa_res->start;
+		m->size = resource_size(cxled->dpa_res);
+		m->position = i;
+	}
+
+	dev = &cxlr_pmem->dev;
+	device_initialize(dev);
+	lockdep_set_class(&dev->mutex, &cxl_pmem_region_key);
+	device_set_pm_not_required(dev);
+	dev->parent = &cxlr->dev;
+	dev->bus = &cxl_bus_type;
+	dev->type = &cxl_pmem_region_type;
+	cxlr_pmem->cxlr = cxlr;
+	cxlr->cxlr_pmem = no_free_ptr(cxlr_pmem);
+
+	return 0;
+}
+
+static void cxlr_pmem_unregister(void *_cxlr_pmem)
+{
+	struct cxl_pmem_region *cxlr_pmem = _cxlr_pmem;
+	struct cxl_region *cxlr = cxlr_pmem->cxlr;
+	struct cxl_nvdimm_bridge *cxl_nvb = cxlr->cxl_nvb;
+
+	/*
+	 * Either the bridge is in ->remove() context under the device_lock(),
+	 * or cxlr_release_nvdimm() is cancelling the bridge's release action
+	 * for @cxlr_pmem and doing it itself (while manually holding the bridge
+	 * lock).
+	 */
+	device_lock_assert(&cxl_nvb->dev);
+	cxlr->cxlr_pmem = NULL;
+	cxlr_pmem->cxlr = NULL;
+	device_unregister(&cxlr_pmem->dev);
+}
+
+static void cxlr_release_nvdimm(void *_cxlr)
+{
+	struct cxl_region *cxlr = _cxlr;
+	struct cxl_nvdimm_bridge *cxl_nvb = cxlr->cxl_nvb;
+
+	scoped_guard(device, &cxl_nvb->dev) {
+		if (cxlr->cxlr_pmem)
+			devm_release_action(&cxl_nvb->dev, cxlr_pmem_unregister,
+					cxlr->cxlr_pmem);
+	}
+	cxlr->cxl_nvb = NULL;
+	put_device(&cxl_nvb->dev);
+}
+
+/**
+ * devm_cxl_add_pmem_region() - add a cxl_region-to-nd_region bridge
+ * @cxlr: parent CXL region for this pmem region bridge device
+ *
+ * Return: 0 on success negative error code on failure.
+ */
+int devm_cxl_add_pmem_region(struct cxl_region *cxlr)
+{
+	struct cxl_pmem_region *cxlr_pmem;
+	struct cxl_nvdimm_bridge *cxl_nvb;
+	struct device *dev;
+	int rc;
+
+	rc = cxl_pmem_region_alloc(cxlr);
+	if (rc)
+		return rc;
+	cxlr_pmem = cxlr->cxlr_pmem;
+	cxl_nvb = cxlr->cxl_nvb;
+
+	dev = &cxlr_pmem->dev;
+	rc = dev_set_name(dev, "pmem_region%d", cxlr->id);
+	if (rc)
+		goto err;
+
+	rc = device_add(dev);
+	if (rc)
+		goto err;
+
+	dev_dbg(&cxlr->dev, "%s: register %s\n", dev_name(dev->parent),
+			dev_name(dev));
+
+	scoped_guard(device, &cxl_nvb->dev) {
+		if (cxl_nvb->dev.driver)
+			rc = devm_add_action_or_reset(&cxl_nvb->dev,
+					cxlr_pmem_unregister,
+					cxlr_pmem);
+		else
+			rc = -ENXIO;
+	}
+
+	if (rc)
+		goto err_bridge;
+
+	/* @cxlr carries a reference on @cxl_nvb until cxlr_release_nvdimm */
+	return devm_add_action_or_reset(&cxlr->dev, cxlr_release_nvdimm, cxlr);
+
+err:
+	put_device(dev);
+err_bridge:
+	put_device(&cxl_nvb->dev);
+	cxlr->cxl_nvb = NULL;
+	return rc;
+}
-- 
2.53.0

On Sun, Mar 22, 2026 at 09:16:36AM -0400, Gregory Price wrote:
> core/region.c is overloaded with per-region control logic (pmem, dax,
> sysram, etc). Move the pmem region driver logic from region.c into
> region_pmem.c make it clear that this code only applies to pmem regions.
> 
> No functional changes.

Reviewed-by: Alison Schofield <alison.schofield@intel.com>

On Sun, 22 Mar 2026 09:16:36 -0400
Gregory Price <gourry@gourry.net> wrote:

> core/region.c is overloaded with per-region control logic (pmem, dax,
> sysram, etc). Move the pmem region driver logic from region.c into
> region_pmem.c make it clear that this code only applies to pmem regions.
> 
> No functional changes.
> 
> Signed-off-by: Gregory Price <gourry@gourry.net>
> ---
>  drivers/cxl/core/Makefile      |   1 +
>  drivers/cxl/core/core.h        |   1 +
>  drivers/cxl/core/region.c      | 184 --------------------------------
>  drivers/cxl/core/region_pmem.c | 189 +++++++++++++++++++++++++++++++++
>  4 files changed, 191 insertions(+), 184 deletions(-)
>  create mode 100644 drivers/cxl/core/region_pmem.c
> 
> diff --git a/drivers/cxl/core/Makefile b/drivers/cxl/core/Makefile
> index a639a9499972..d1484a0e5eb4 100644
> --- a/drivers/cxl/core/Makefile
> +++ b/drivers/cxl/core/Makefile
> @@ -16,6 +16,7 @@ cxl_core-y += pmu.o
>  cxl_core-y += cdat.o
>  cxl_core-$(CONFIG_TRACING) += trace.o
>  cxl_core-$(CONFIG_CXL_REGION) += region.o
> +cxl_core-$(CONFIG_CXL_REGION) += region_pmem.o

cxl_core-$(CONFIG_CXL_REGION) += region.o region_pmem.o

For me having them on one line makes it more obvious it's
either neither or both. Cost is a bit more churn if you
decide later to split the CONFIG_* up.

>  cxl_core-$(CONFIG_CXL_MCE) += mce.o
>  cxl_core-$(CONFIG_CXL_FEATURES) += features.o
>  cxl_core-$(CONFIG_CXL_EDAC_MEM_FEATURES) += edac.o
Otherwise a couple of white space things. + a passing comment on the lifetime
management being more complex than I'd like.

Fix the white space and you can add
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>

> diff --git a/drivers/cxl/core/region_pmem.c b/drivers/cxl/core/region_pmem.c
> new file mode 100644
> index 000000000000..138c373a5700
> --- /dev/null
> +++ b/drivers/cxl/core/region_pmem.c

> +const struct device_type cxl_pmem_region_type = {
> +	.name = "cxl_pmem_region",
> +	.release = cxl_pmem_region_release,
> +	.groups = cxl_pmem_region_attribute_groups,
> +};

Blank line here. There is one in the original and I can't see why
we'd want to get rid of it.

> +bool is_cxl_pmem_region(struct device *dev)
> +{
> +	return dev->type == &cxl_pmem_region_type;
> +}
> +EXPORT_SYMBOL_NS_GPL(is_cxl_pmem_region, "CXL");
> +
> +struct cxl_pmem_region *to_cxl_pmem_region(struct device *dev)
> +{
> +	if (dev_WARN_ONCE(dev, !is_cxl_pmem_region(dev),
> +				"not a cxl_pmem_region device\n"))
> +		return NULL;
> +	return container_of(dev, struct cxl_pmem_region, dev);
> +}
> +EXPORT_SYMBOL_NS_GPL(to_cxl_pmem_region, "CXL");

Blank line here probably makes sense as the key has nothing to do
with the EXPORT_SYMBOL...


> +static struct lock_class_key cxl_pmem_region_key;
> +

> +
> +/**
> + * devm_cxl_add_pmem_region() - add a cxl_region-to-nd_region bridge
> + * @cxlr: parent CXL region for this pmem region bridge device
> + *
> + * Return: 0 on success negative error code on failure.

FWIW the lifetime management in here feels way to complex to me.  Not
a problem for this patch and I'm not immediately sure what we can do about it.

> + */
> +int devm_cxl_add_pmem_region(struct cxl_region *cxlr)
> +{
> +	struct cxl_pmem_region *cxlr_pmem;
> +	struct cxl_nvdimm_bridge *cxl_nvb;
> +	struct device *dev;
> +	int rc;
> +
> +	rc = cxl_pmem_region_alloc(cxlr);
> +	if (rc)
> +		return rc;
> +	cxlr_pmem = cxlr->cxlr_pmem;
> +	cxl_nvb = cxlr->cxl_nvb;
> +
> +	dev = &cxlr_pmem->dev;
> +	rc = dev_set_name(dev, "pmem_region%d", cxlr->id);
> +	if (rc)
> +		goto err;
> +
> +	rc = device_add(dev);
> +	if (rc)
> +		goto err;
> +
> +	dev_dbg(&cxlr->dev, "%s: register %s\n", dev_name(dev->parent),
> +			dev_name(dev));
> +
> +	scoped_guard(device, &cxl_nvb->dev) {
> +		if (cxl_nvb->dev.driver)
> +			rc = devm_add_action_or_reset(&cxl_nvb->dev,
> +					cxlr_pmem_unregister,
> +					cxlr_pmem);
> +		else
> +			rc = -ENXIO;
As an example. If we happen to take this path... Where is the device_add() undone?
> +	}
> +
> +	if (rc)
> +		goto err_bridge;
> +
> +	/* @cxlr carries a reference on @cxl_nvb until cxlr_release_nvdimm */
> +	return devm_add_action_or_reset(&cxlr->dev, cxlr_release_nvdimm, cxlr);
> +
> +err:
> +	put_device(dev);
> +err_bridge:
> +	put_device(&cxl_nvb->dev);
> +	cxlr->cxl_nvb = NULL;
> +	return rc;
> +}

On Mon, Mar 23, 2026 at 03:08:47PM +0000, Jonathan Cameron wrote:
> On Sun, 22 Mar 2026 09:16:36 -0400
> Gregory Price <gourry@gourry.net> wrote:
> 
> > +	scoped_guard(device, &cxl_nvb->dev) {
> > +		if (cxl_nvb->dev.driver)
> > +			rc = devm_add_action_or_reset(&cxl_nvb->dev,
> > +					cxlr_pmem_unregister,
> > +					cxlr_pmem);
> > +		else
> > +			rc = -ENXIO;
> As an example. If we happen to take this path... Where is the device_add() undone?

In many other parts of the code, device_add is not rolled back either
"for reasons", and - depending on who you talk to - this is
intentional... for debugging?

I dunno, but the "hanging objects on failure" thing is common throughout
cxl/ - :shrug:

~Gregory

On Mon, 23 Mar 2026 10:47:51 -0500
Gregory Price <gourry@gourry.net> wrote:

> On Mon, Mar 23, 2026 at 03:08:47PM +0000, Jonathan Cameron wrote:
> > On Sun, 22 Mar 2026 09:16:36 -0400
> > Gregory Price <gourry@gourry.net> wrote:
> >   
> > > +	scoped_guard(device, &cxl_nvb->dev) {
> > > +		if (cxl_nvb->dev.driver)
> > > +			rc = devm_add_action_or_reset(&cxl_nvb->dev,
> > > +					cxlr_pmem_unregister,
> > > +					cxlr_pmem);
> > > +		else
> > > +			rc = -ENXIO;  
> > As an example. If we happen to take this path... Where is the device_add() undone?  
> 
> In many other parts of the code, device_add is not rolled back either
> "for reasons", and - depending on who you talk to - this is
> intentional... for debugging?
> 
> I dunno, but the "hanging objects on failure" thing is common throughout
> cxl/ - :shrug:

If it were consistent maybe, but in other paths in this function it is cleaned up...
So I call bug even if it's one that is relatively unlikely to actually happen.

J
> 
> ~Gregory

On Sun, Mar 22, 2026 at 09:16:36AM -0400, Gregory Price wrote:
> core/region.c is overloaded with per-region control logic (pmem, dax,
> sysram, etc). Move the pmem region driver logic from region.c into
> region_pmem.c make it clear that this code only applies to pmem regions.
> 
> No functional changes.

This always adds region_pmem.o regardless of CONFIG_CXL_PMEM.
Are you heading towards conditionally compiling, where region_pmem.o is
omitted if !CONFIG_CXL_PMEM? 

Similar question for region_dax.o

--Alison

> 
> Signed-off-by: Gregory Price <gourry@gourry.net>
> ---
>  drivers/cxl/core/Makefile      |   1 +
>  drivers/cxl/core/core.h        |   1 +
>  drivers/cxl/core/region.c      | 184 --------------------------------
>  drivers/cxl/core/region_pmem.c | 189 +++++++++++++++++++++++++++++++++
>  4 files changed, 191 insertions(+), 184 deletions(-)
>  create mode 100644 drivers/cxl/core/region_pmem.c
> 
> diff --git a/drivers/cxl/core/Makefile b/drivers/cxl/core/Makefile
> index a639a9499972..d1484a0e5eb4 100644
> --- a/drivers/cxl/core/Makefile
> +++ b/drivers/cxl/core/Makefile
> @@ -16,6 +16,7 @@ cxl_core-y += pmu.o
>  cxl_core-y += cdat.o
>  cxl_core-$(CONFIG_TRACING) += trace.o
>  cxl_core-$(CONFIG_CXL_REGION) += region.o
> +cxl_core-$(CONFIG_CXL_REGION) += region_pmem.o
>  cxl_core-$(CONFIG_CXL_MCE) += mce.o
>  cxl_core-$(CONFIG_CXL_FEATURES) += features.o
>  cxl_core-$(CONFIG_CXL_EDAC_MEM_FEATURES) += edac.o
> diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
> index 5539e941782f..ef03966eeabd 100644
> --- a/drivers/cxl/core/core.h
> +++ b/drivers/cxl/core/core.h
> @@ -50,6 +50,7 @@ int cxl_get_poison_by_endpoint(struct cxl_port *port);
>  struct cxl_region *cxl_dpa_to_region(const struct cxl_memdev *cxlmd, u64 dpa);
>  u64 cxl_dpa_to_hpa(struct cxl_region *cxlr, const struct cxl_memdev *cxlmd,
>  		   u64 dpa);
> +int devm_cxl_add_pmem_region(struct cxl_region *cxlr);
>  
>  #else
>  static inline u64 cxl_dpa_to_hpa(struct cxl_region *cxlr,
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index f24b7e754727..72aee1408efb 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -2781,46 +2781,6 @@ static ssize_t delete_region_store(struct device *dev,
>  }
>  DEVICE_ATTR_WO(delete_region);
>  
> -static void cxl_pmem_region_release(struct device *dev)
> -{
> -	struct cxl_pmem_region *cxlr_pmem = to_cxl_pmem_region(dev);
> -	int i;
> -
> -	for (i = 0; i < cxlr_pmem->nr_mappings; i++) {
> -		struct cxl_memdev *cxlmd = cxlr_pmem->mapping[i].cxlmd;
> -
> -		put_device(&cxlmd->dev);
> -	}
> -
> -	kfree(cxlr_pmem);
> -}
> -
> -static const struct attribute_group *cxl_pmem_region_attribute_groups[] = {
> -	&cxl_base_attribute_group,
> -	NULL,
> -};
> -
> -const struct device_type cxl_pmem_region_type = {
> -	.name = "cxl_pmem_region",
> -	.release = cxl_pmem_region_release,
> -	.groups = cxl_pmem_region_attribute_groups,
> -};
> -
> -bool is_cxl_pmem_region(struct device *dev)
> -{
> -	return dev->type == &cxl_pmem_region_type;
> -}
> -EXPORT_SYMBOL_NS_GPL(is_cxl_pmem_region, "CXL");
> -
> -struct cxl_pmem_region *to_cxl_pmem_region(struct device *dev)
> -{
> -	if (dev_WARN_ONCE(dev, !is_cxl_pmem_region(dev),
> -			  "not a cxl_pmem_region device\n"))
> -		return NULL;
> -	return container_of(dev, struct cxl_pmem_region, dev);
> -}
> -EXPORT_SYMBOL_NS_GPL(to_cxl_pmem_region, "CXL");
> -
>  struct cxl_poison_context {
>  	struct cxl_port *port;
>  	int part;
> @@ -3476,64 +3436,6 @@ static int region_offset_to_dpa_result(struct cxl_region *cxlr, u64 offset,
>  	return -ENXIO;
>  }
>  
> -static struct lock_class_key cxl_pmem_region_key;
> -
> -static int cxl_pmem_region_alloc(struct cxl_region *cxlr)
> -{
> -	struct cxl_region_params *p = &cxlr->params;
> -	struct cxl_nvdimm_bridge *cxl_nvb;
> -	struct device *dev;
> -	int i;
> -
> -	guard(rwsem_read)(&cxl_rwsem.region);
> -	if (p->state != CXL_CONFIG_COMMIT)
> -		return -ENXIO;
> -
> -	struct cxl_pmem_region *cxlr_pmem __free(kfree) =
> -		kzalloc_flex(*cxlr_pmem, mapping, p->nr_targets);
> -	if (!cxlr_pmem)
> -		return -ENOMEM;
> -
> -	cxlr_pmem->hpa_range.start = p->res->start;
> -	cxlr_pmem->hpa_range.end = p->res->end;
> -
> -	/* Snapshot the region configuration underneath the cxl_rwsem.region */
> -	cxlr_pmem->nr_mappings = p->nr_targets;
> -	for (i = 0; i < p->nr_targets; i++) {
> -		struct cxl_endpoint_decoder *cxled = p->targets[i];
> -		struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
> -		struct cxl_pmem_region_mapping *m = &cxlr_pmem->mapping[i];
> -
> -		/*
> -		 * Regions never span CXL root devices, so by definition the
> -		 * bridge for one device is the same for all.
> -		 */
> -		if (i == 0) {
> -			cxl_nvb = cxl_find_nvdimm_bridge(cxlmd->endpoint);
> -			if (!cxl_nvb)
> -				return -ENODEV;
> -			cxlr->cxl_nvb = cxl_nvb;
> -		}
> -		m->cxlmd = cxlmd;
> -		get_device(&cxlmd->dev);
> -		m->start = cxled->dpa_res->start;
> -		m->size = resource_size(cxled->dpa_res);
> -		m->position = i;
> -	}
> -
> -	dev = &cxlr_pmem->dev;
> -	device_initialize(dev);
> -	lockdep_set_class(&dev->mutex, &cxl_pmem_region_key);
> -	device_set_pm_not_required(dev);
> -	dev->parent = &cxlr->dev;
> -	dev->bus = &cxl_bus_type;
> -	dev->type = &cxl_pmem_region_type;
> -	cxlr_pmem->cxlr = cxlr;
> -	cxlr->cxlr_pmem = no_free_ptr(cxlr_pmem);
> -
> -	return 0;
> -}
> -
>  static void cxl_dax_region_release(struct device *dev)
>  {
>  	struct cxl_dax_region *cxlr_dax = to_cxl_dax_region(dev);
> @@ -3597,92 +3499,6 @@ static struct cxl_dax_region *cxl_dax_region_alloc(struct cxl_region *cxlr)
>  	return cxlr_dax;
>  }
>  
> -static void cxlr_pmem_unregister(void *_cxlr_pmem)
> -{
> -	struct cxl_pmem_region *cxlr_pmem = _cxlr_pmem;
> -	struct cxl_region *cxlr = cxlr_pmem->cxlr;
> -	struct cxl_nvdimm_bridge *cxl_nvb = cxlr->cxl_nvb;
> -
> -	/*
> -	 * Either the bridge is in ->remove() context under the device_lock(),
> -	 * or cxlr_release_nvdimm() is cancelling the bridge's release action
> -	 * for @cxlr_pmem and doing it itself (while manually holding the bridge
> -	 * lock).
> -	 */
> -	device_lock_assert(&cxl_nvb->dev);
> -	cxlr->cxlr_pmem = NULL;
> -	cxlr_pmem->cxlr = NULL;
> -	device_unregister(&cxlr_pmem->dev);
> -}
> -
> -static void cxlr_release_nvdimm(void *_cxlr)
> -{
> -	struct cxl_region *cxlr = _cxlr;
> -	struct cxl_nvdimm_bridge *cxl_nvb = cxlr->cxl_nvb;
> -
> -	scoped_guard(device, &cxl_nvb->dev) {
> -		if (cxlr->cxlr_pmem)
> -			devm_release_action(&cxl_nvb->dev, cxlr_pmem_unregister,
> -					    cxlr->cxlr_pmem);
> -	}
> -	cxlr->cxl_nvb = NULL;
> -	put_device(&cxl_nvb->dev);
> -}
> -
> -/**
> - * devm_cxl_add_pmem_region() - add a cxl_region-to-nd_region bridge
> - * @cxlr: parent CXL region for this pmem region bridge device
> - *
> - * Return: 0 on success negative error code on failure.
> - */
> -static int devm_cxl_add_pmem_region(struct cxl_region *cxlr)
> -{
> -	struct cxl_pmem_region *cxlr_pmem;
> -	struct cxl_nvdimm_bridge *cxl_nvb;
> -	struct device *dev;
> -	int rc;
> -
> -	rc = cxl_pmem_region_alloc(cxlr);
> -	if (rc)
> -		return rc;
> -	cxlr_pmem = cxlr->cxlr_pmem;
> -	cxl_nvb = cxlr->cxl_nvb;
> -
> -	dev = &cxlr_pmem->dev;
> -	rc = dev_set_name(dev, "pmem_region%d", cxlr->id);
> -	if (rc)
> -		goto err;
> -
> -	rc = device_add(dev);
> -	if (rc)
> -		goto err;
> -
> -	dev_dbg(&cxlr->dev, "%s: register %s\n", dev_name(dev->parent),
> -		dev_name(dev));
> -
> -	scoped_guard(device, &cxl_nvb->dev) {
> -		if (cxl_nvb->dev.driver)
> -			rc = devm_add_action_or_reset(&cxl_nvb->dev,
> -						      cxlr_pmem_unregister,
> -						      cxlr_pmem);
> -		else
> -			rc = -ENXIO;
> -	}
> -
> -	if (rc)
> -		goto err_bridge;
> -
> -	/* @cxlr carries a reference on @cxl_nvb until cxlr_release_nvdimm */
> -	return devm_add_action_or_reset(&cxlr->dev, cxlr_release_nvdimm, cxlr);
> -
> -err:
> -	put_device(dev);
> -err_bridge:
> -	put_device(&cxl_nvb->dev);
> -	cxlr->cxl_nvb = NULL;
> -	return rc;
> -}
> -
>  static void cxlr_dax_unregister(void *_cxlr_dax)
>  {
>  	struct cxl_dax_region *cxlr_dax = _cxlr_dax;
> diff --git a/drivers/cxl/core/region_pmem.c b/drivers/cxl/core/region_pmem.c
> new file mode 100644
> index 000000000000..138c373a5700
> --- /dev/null
> +++ b/drivers/cxl/core/region_pmem.c
> @@ -0,0 +1,189 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/* Copyright(c) 2022 Intel Corporation. All rights reserved. */
> +#include <linux/device.h>
> +#include <linux/slab.h>
> +#include <cxlmem.h>
> +#include <cxl.h>
> +#include "core.h"
> +
> +static void cxl_pmem_region_release(struct device *dev)
> +{
> +	struct cxl_pmem_region *cxlr_pmem = to_cxl_pmem_region(dev);
> +	int i;
> +
> +	for (i = 0; i < cxlr_pmem->nr_mappings; i++) {
> +		struct cxl_memdev *cxlmd = cxlr_pmem->mapping[i].cxlmd;
> +
> +		put_device(&cxlmd->dev);
> +	}
> +
> +	kfree(cxlr_pmem);
> +}
> +
> +static const struct attribute_group *cxl_pmem_region_attribute_groups[] = {
> +	&cxl_base_attribute_group,
> +	NULL
> +};
> +
> +const struct device_type cxl_pmem_region_type = {
> +	.name = "cxl_pmem_region",
> +	.release = cxl_pmem_region_release,
> +	.groups = cxl_pmem_region_attribute_groups,
> +};
> +bool is_cxl_pmem_region(struct device *dev)
> +{
> +	return dev->type == &cxl_pmem_region_type;
> +}
> +EXPORT_SYMBOL_NS_GPL(is_cxl_pmem_region, "CXL");
> +
> +struct cxl_pmem_region *to_cxl_pmem_region(struct device *dev)
> +{
> +	if (dev_WARN_ONCE(dev, !is_cxl_pmem_region(dev),
> +				"not a cxl_pmem_region device\n"))
> +		return NULL;
> +	return container_of(dev, struct cxl_pmem_region, dev);
> +}
> +EXPORT_SYMBOL_NS_GPL(to_cxl_pmem_region, "CXL");
> +static struct lock_class_key cxl_pmem_region_key;
> +
> +static int cxl_pmem_region_alloc(struct cxl_region *cxlr)
> +{
> +	struct cxl_region_params *p = &cxlr->params;
> +	struct cxl_nvdimm_bridge *cxl_nvb;
> +	struct device *dev;
> +	int i;
> +
> +	guard(rwsem_read)(&cxl_rwsem.region);
> +	if (p->state != CXL_CONFIG_COMMIT)
> +		return -ENXIO;
> +
> +	struct cxl_pmem_region *cxlr_pmem __free(kfree) =
> +		kzalloc_flex(*cxlr_pmem, mapping, p->nr_targets);
> +	if (!cxlr_pmem)
> +		return -ENOMEM;
> +
> +	cxlr_pmem->hpa_range.start = p->res->start;
> +	cxlr_pmem->hpa_range.end = p->res->end;
> +
> +	/* Snapshot the region configuration underneath the cxl_rwsem.region */
> +	cxlr_pmem->nr_mappings = p->nr_targets;
> +	for (i = 0; i < p->nr_targets; i++) {
> +		struct cxl_endpoint_decoder *cxled = p->targets[i];
> +		struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
> +		struct cxl_pmem_region_mapping *m = &cxlr_pmem->mapping[i];
> +
> +		/*
> +		 * Regions never span CXL root devices, so by definition the
> +		 * bridge for one device is the same for all.
> +		 */
> +		if (i == 0) {
> +			cxl_nvb = cxl_find_nvdimm_bridge(cxlmd->endpoint);
> +			if (!cxl_nvb)
> +				return -ENODEV;
> +			cxlr->cxl_nvb = cxl_nvb;
> +		}
> +		m->cxlmd = cxlmd;
> +		get_device(&cxlmd->dev);
> +		m->start = cxled->dpa_res->start;
> +		m->size = resource_size(cxled->dpa_res);
> +		m->position = i;
> +	}
> +
> +	dev = &cxlr_pmem->dev;
> +	device_initialize(dev);
> +	lockdep_set_class(&dev->mutex, &cxl_pmem_region_key);
> +	device_set_pm_not_required(dev);
> +	dev->parent = &cxlr->dev;
> +	dev->bus = &cxl_bus_type;
> +	dev->type = &cxl_pmem_region_type;
> +	cxlr_pmem->cxlr = cxlr;
> +	cxlr->cxlr_pmem = no_free_ptr(cxlr_pmem);
> +
> +	return 0;
> +}
> +
> +static void cxlr_pmem_unregister(void *_cxlr_pmem)
> +{
> +	struct cxl_pmem_region *cxlr_pmem = _cxlr_pmem;
> +	struct cxl_region *cxlr = cxlr_pmem->cxlr;
> +	struct cxl_nvdimm_bridge *cxl_nvb = cxlr->cxl_nvb;
> +
> +	/*
> +	 * Either the bridge is in ->remove() context under the device_lock(),
> +	 * or cxlr_release_nvdimm() is cancelling the bridge's release action
> +	 * for @cxlr_pmem and doing it itself (while manually holding the bridge
> +	 * lock).
> +	 */
> +	device_lock_assert(&cxl_nvb->dev);
> +	cxlr->cxlr_pmem = NULL;
> +	cxlr_pmem->cxlr = NULL;
> +	device_unregister(&cxlr_pmem->dev);
> +}
> +
> +static void cxlr_release_nvdimm(void *_cxlr)
> +{
> +	struct cxl_region *cxlr = _cxlr;
> +	struct cxl_nvdimm_bridge *cxl_nvb = cxlr->cxl_nvb;
> +
> +	scoped_guard(device, &cxl_nvb->dev) {
> +		if (cxlr->cxlr_pmem)
> +			devm_release_action(&cxl_nvb->dev, cxlr_pmem_unregister,
> +					cxlr->cxlr_pmem);
> +	}
> +	cxlr->cxl_nvb = NULL;
> +	put_device(&cxl_nvb->dev);
> +}
> +
> +/**
> + * devm_cxl_add_pmem_region() - add a cxl_region-to-nd_region bridge
> + * @cxlr: parent CXL region for this pmem region bridge device
> + *
> + * Return: 0 on success negative error code on failure.
> + */
> +int devm_cxl_add_pmem_region(struct cxl_region *cxlr)
> +{
> +	struct cxl_pmem_region *cxlr_pmem;
> +	struct cxl_nvdimm_bridge *cxl_nvb;
> +	struct device *dev;
> +	int rc;
> +
> +	rc = cxl_pmem_region_alloc(cxlr);
> +	if (rc)
> +		return rc;
> +	cxlr_pmem = cxlr->cxlr_pmem;
> +	cxl_nvb = cxlr->cxl_nvb;
> +
> +	dev = &cxlr_pmem->dev;
> +	rc = dev_set_name(dev, "pmem_region%d", cxlr->id);
> +	if (rc)
> +		goto err;
> +
> +	rc = device_add(dev);
> +	if (rc)
> +		goto err;
> +
> +	dev_dbg(&cxlr->dev, "%s: register %s\n", dev_name(dev->parent),
> +			dev_name(dev));
> +
> +	scoped_guard(device, &cxl_nvb->dev) {
> +		if (cxl_nvb->dev.driver)
> +			rc = devm_add_action_or_reset(&cxl_nvb->dev,
> +					cxlr_pmem_unregister,
> +					cxlr_pmem);
> +		else
> +			rc = -ENXIO;
> +	}
> +
> +	if (rc)
> +		goto err_bridge;
> +
> +	/* @cxlr carries a reference on @cxl_nvb until cxlr_release_nvdimm */
> +	return devm_add_action_or_reset(&cxlr->dev, cxlr_release_nvdimm, cxlr);
> +
> +err:
> +	put_device(dev);
> +err_bridge:
> +	put_device(&cxl_nvb->dev);
> +	cxlr->cxl_nvb = NULL;
> +	return rc;
> +}
> -- 
> 2.53.0
>

On Sun, Mar 22, 2026 at 07:37:28PM -0700, Alison Schofield wrote:
> On Sun, Mar 22, 2026 at 09:16:36AM -0400, Gregory Price wrote:
> > core/region.c is overloaded with per-region control logic (pmem, dax,
> > sysram, etc). Move the pmem region driver logic from region.c into
> > region_pmem.c make it clear that this code only applies to pmem regions.
> > 
> > No functional changes.
> 
> This always adds region_pmem.o regardless of CONFIG_CXL_PMEM.
> Are you heading towards conditionally compiling, where region_pmem.o is
> omitted if !CONFIG_CXL_PMEM? 
> 
> Similar question for region_dax.o
> 

I hadn't considered going that far, but it doesn't seem unreasonable?

It just seemed natural to break out the code this way, but I don't know
if adding more Kconfig cruft is worth it just to save some .o's and a
smaller amount of code.

The recent pmem/nvdimm Kconfig change does kind of show that we might
have some bloat for some deployments which might not care about pmem -
for example.

~Gregory

On Mon, Mar 23, 2026 at 01:37:49AM -0400, Gregory Price wrote:
> On Sun, Mar 22, 2026 at 07:37:28PM -0700, Alison Schofield wrote:
> > On Sun, Mar 22, 2026 at 09:16:36AM -0400, Gregory Price wrote:
> > > core/region.c is overloaded with per-region control logic (pmem, dax,
> > > sysram, etc). Move the pmem region driver logic from region.c into
> > > region_pmem.c make it clear that this code only applies to pmem regions.
> > > 
> > > No functional changes.
> > 
> > This always adds region_pmem.o regardless of CONFIG_CXL_PMEM.
> > Are you heading towards conditionally compiling, where region_pmem.o is
> > omitted if !CONFIG_CXL_PMEM? 
> > 
> > Similar question for region_dax.o
> > 
> 
> I hadn't considered going that far, but it doesn't seem unreasonable?
> 
> It just seemed natural to break out the code this way, but I don't know
> if adding more Kconfig cruft is worth it just to save some .o's and a
> smaller amount of code.
> 
> The recent pmem/nvdimm Kconfig change does kind of show that we might
> have some bloat for some deployments which might not care about pmem -
> for example.

I guess my original thought was, what is your long term intent with
the move?  And I was thinking you are probably heading to conditionally
compiling.  HOWEVER, now the scaredy-cat-me is thinking, shoot, that 
would add test config complexity and test misses. ie. Folks make a
change in region_dax.c, don't test with CONFIG_CXL_PMEM enabled, and
boom.

So, I lean towards keeping them all (working) together, like you have.

-- Alison


> 
> ~Gregory

On Mon, Mar 23, 2026 at 08:49:02PM -0700, Alison Schofield wrote:
> On Mon, Mar 23, 2026 at 01:37:49AM -0400, Gregory Price wrote:
> > 
> > The recent pmem/nvdimm Kconfig change does kind of show that we might
> > have some bloat for some deployments which might not care about pmem -
> > for example.
> 
> I guess my original thought was, what is your long term intent with
> the move?  And I was thinking you are probably heading to conditionally
> compiling.  HOWEVER, now the scaredy-cat-me is thinking, shoot, that 
> would add test config complexity and test misses. ie. Folks make a
> change in region_dax.c, don't test with CONFIG_CXL_PMEM enabled, and
> boom.
> 
> So, I lean towards keeping them all (working) together, like you have.
>

fwiw i think this is the right take.  It doesn't really cost us anything
to keep in, and probably prevents adding more Kconfig footguns.

~Gregory