driver-core, libnvdimm: Let device subsystems add local lockdep coverage

For good reason, the standard device_lock() is marked
lockdep_set_novalidate_class() because there is simply no sane way to
describe the myriad ways the device_lock() ordered with other locks.
However, that leaves subsystems that know their own local device_lock()
ordering rules to find lock ordering mistakes manually. Instead,
introduce an optional / additional lockdep-enabled lock that a subsystem
can acquire in all the same paths that the device_lock() is acquired.

A conversion of the NFIT driver and NVDIMM subsystem to a
lockdep-validate device_lock() scheme is included. The
debug_nvdimm_lock() implementation implements the correct lock-class and
stacking order for the libnvdimm device topology hierarchy.

Yes, this is a hack, but hopefully it is a useful hack for other
subsystems device_lock() debug sessions. Quoting Greg:

    "Yeah, it feels a bit hacky but it's really up to a subsystem to mess up
     using it as much as anything else, so user beware :)

     I don't object to it if it makes things easier for you to debug."

Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Link: https://lore.kernel.org/r/156341210661.292348.7014034644265455704.stgit@dwillia2-desk3.amr.corp.intel.com

drivers/acpi/nfit/core.c

@@ -1282,7 +1282,7 @@ static ssize_t hw_error_scrub_store(struct device *dev,
 	if (rc)
 		return rc;
 
-	device_lock(dev);
+	nfit_device_lock(dev);
 	nd_desc = dev_get_drvdata(dev);
 	if (nd_desc) {
 		struct acpi_nfit_desc *acpi_desc = to_acpi_desc(nd_desc);
@@ -1299,7 +1299,7 @@ static ssize_t hw_error_scrub_store(struct device *dev,
 			break;
 		}
 	}
-	device_unlock(dev);
+	nfit_device_unlock(dev);
 	if (rc)
 		return rc;
 	return size;
@@ -1319,7 +1319,7 @@ static ssize_t scrub_show(struct device *dev,
 	ssize_t rc = -ENXIO;
 	bool busy;
 
-	device_lock(dev);
+	nfit_device_lock(dev);
 	nd_desc = dev_get_drvdata(dev);
 	if (!nd_desc) {
 		device_unlock(dev);
@@ -1339,7 +1339,7 @@ static ssize_t scrub_show(struct device *dev,
 	}
 
 	mutex_unlock(&acpi_desc->init_mutex);
-	device_unlock(dev);
+	nfit_device_unlock(dev);
 	return rc;
 }
 
@@ -1356,14 +1356,14 @@ static ssize_t scrub_store(struct device *dev,
 	if (val != 1)
 		return -EINVAL;
 
-	device_lock(dev);
+	nfit_device_lock(dev);
 	nd_desc = dev_get_drvdata(dev);
 	if (nd_desc) {
 		struct acpi_nfit_desc *acpi_desc = to_acpi_desc(nd_desc);
 
 		rc = acpi_nfit_ars_rescan(acpi_desc, ARS_REQ_LONG);
 	}
-	device_unlock(dev);
+	nfit_device_unlock(dev);
 	if (rc)
 		return rc;
 	return size;
@@ -1749,9 +1749,9 @@ static void acpi_nvdimm_notify(acpi_handle handle, u32 event, void *data)
 	struct acpi_device *adev = data;
 	struct device *dev = &adev->dev;
 
-	device_lock(dev->parent);
+	nfit_device_lock(dev->parent);
 	__acpi_nvdimm_notify(dev, event);
-	device_unlock(dev->parent);
+	nfit_device_unlock(dev->parent);
 }
 
 static bool acpi_nvdimm_has_method(struct acpi_device *adev, char *method)
@@ -3457,8 +3457,8 @@ static int acpi_nfit_flush_probe(struct nvdimm_bus_descriptor *nd_desc)
 	struct device *dev = acpi_desc->dev;
 
 	/* Bounce the device lock to flush acpi_nfit_add / acpi_nfit_notify */
-	device_lock(dev);
-	device_unlock(dev);
+	nfit_device_lock(dev);
+	nfit_device_unlock(dev);
 
 	/* Bounce the init_mutex to complete initial registration */
 	mutex_lock(&acpi_desc->init_mutex);
@@ -3602,8 +3602,8 @@ void acpi_nfit_shutdown(void *data)
 	 * acpi_nfit_ars_rescan() submissions have had a chance to
 	 * either submit or see ->cancel set.
 	 */
-	device_lock(bus_dev);
-	device_unlock(bus_dev);
+	nfit_device_lock(bus_dev);
+	nfit_device_unlock(bus_dev);
 
 	flush_workqueue(nfit_wq);
 }
@@ -3746,9 +3746,9 @@ EXPORT_SYMBOL_GPL(__acpi_nfit_notify);
 
 static void acpi_nfit_notify(struct acpi_device *adev, u32 event)
 {
-	device_lock(&adev->dev);
+	nfit_device_lock(&adev->dev);
 	__acpi_nfit_notify(&adev->dev, adev->handle, event);
-	device_unlock(&adev->dev);
+	nfit_device_unlock(&adev->dev);
 }
 
 static const struct acpi_device_id acpi_nfit_ids[] = {

drivers/acpi/nfit/nfit.h

@@ -312,6 +312,30 @@ static inline struct acpi_nfit_desc *to_acpi_desc(
 	return container_of(nd_desc, struct acpi_nfit_desc, nd_desc);
 }
 
+#ifdef CONFIG_PROVE_LOCKING
+static inline void nfit_device_lock(struct device *dev)
+{
+	device_lock(dev);
+	mutex_lock(&dev->lockdep_mutex);
+}
+
+static inline void nfit_device_unlock(struct device *dev)
+{
+	mutex_unlock(&dev->lockdep_mutex);
+	device_unlock(dev);
+}
+#else
+static inline void nfit_device_lock(struct device *dev)
+{
+	device_lock(dev);
+}
+
+static inline void nfit_device_unlock(struct device *dev)
+{
+	device_unlock(dev);
+}
+#endif
+
 const guid_t *to_nfit_uuid(enum nfit_uuids id);
 int acpi_nfit_init(struct acpi_nfit_desc *acpi_desc, void *nfit, acpi_size sz);
 void acpi_nfit_shutdown(void *data);

drivers/base/core.c

@@ -1663,6 +1663,9 @@ void device_initialize(struct device *dev)
 	kobject_init(&dev->kobj, &device_ktype);
 	INIT_LIST_HEAD(&dev->dma_pools);
 	mutex_init(&dev->mutex);
+#ifdef CONFIG_PROVE_LOCKING
+	mutex_init(&dev->lockdep_mutex);
+#endif
 	lockdep_set_novalidate_class(&dev->mutex);
 	spin_lock_init(&dev->devres_lock);
 	INIT_LIST_HEAD(&dev->devres_head);

drivers/nvdimm/btt_devs.c

@@ -62,14 +62,14 @@ static ssize_t sector_size_store(struct device *dev,
 	struct nd_btt *nd_btt = to_nd_btt(dev);
 	ssize_t rc;
 
-	device_lock(dev);
+	nd_device_lock(dev);
 	nvdimm_bus_lock(dev);
 	rc = nd_size_select_store(dev, buf, &nd_btt->lbasize,
 			btt_lbasize_supported);
 	dev_dbg(dev, "result: %zd wrote: %s%s", rc, buf,
 			buf[len - 1] == '\n' ? "" : "\n");
 	nvdimm_bus_unlock(dev);
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	return rc ? rc : len;
 }
@@ -91,11 +91,11 @@ static ssize_t uuid_store(struct device *dev,
 	struct nd_btt *nd_btt = to_nd_btt(dev);
 	ssize_t rc;
 
-	device_lock(dev);
+	nd_device_lock(dev);
 	rc = nd_uuid_store(dev, &nd_btt->uuid, buf, len);
 	dev_dbg(dev, "result: %zd wrote: %s%s", rc, buf,
 			buf[len - 1] == '\n' ? "" : "\n");
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	return rc ? rc : len;
 }
@@ -120,13 +120,13 @@ static ssize_t namespace_store(struct device *dev,
 	struct nd_btt *nd_btt = to_nd_btt(dev);
 	ssize_t rc;
 
-	device_lock(dev);
+	nd_device_lock(dev);
 	nvdimm_bus_lock(dev);
 	rc = nd_namespace_store(dev, &nd_btt->ndns, buf, len);
 	dev_dbg(dev, "result: %zd wrote: %s%s", rc, buf,
 			buf[len - 1] == '\n' ? "" : "\n");
 	nvdimm_bus_unlock(dev);
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	return rc;
 }
@@ -138,14 +138,14 @@ static ssize_t size_show(struct device *dev,
 	struct nd_btt *nd_btt = to_nd_btt(dev);
 	ssize_t rc;
 
-	device_lock(dev);
+	nd_device_lock(dev);
 	if (dev->driver)
 		rc = sprintf(buf, "%llu\n", nd_btt->size);
 	else {
 		/* no size to convey if the btt instance is disabled */
 		rc = -ENXIO;
 	}
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	return rc;
 }

drivers/nvdimm/bus.c

@@ -26,7 +26,7 @@
 
 int nvdimm_major;
 static int nvdimm_bus_major;
-static struct class *nd_class;
+struct class *nd_class;
 static DEFINE_IDA(nd_ida);
 
 static int to_nd_device_type(struct device *dev)
@@ -91,7 +91,10 @@ static int nvdimm_bus_probe(struct device *dev)
 			dev->driver->name, dev_name(dev));
 
 	nvdimm_bus_probe_start(nvdimm_bus);
+	debug_nvdimm_lock(dev);
 	rc = nd_drv->probe(dev);
+	debug_nvdimm_unlock(dev);
+
 	if (rc == 0)
 		nd_region_probe_success(nvdimm_bus, dev);
 	else
@@ -113,8 +116,11 @@ static int nvdimm_bus_remove(struct device *dev)
 	struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);
 	int rc = 0;
 
-	if (nd_drv->remove)
+	if (nd_drv->remove) {
+		debug_nvdimm_lock(dev);
 		rc = nd_drv->remove(dev);
+		debug_nvdimm_unlock(dev);
+	}
 	nd_region_disable(nvdimm_bus, dev);
 
 	dev_dbg(&nvdimm_bus->dev, "%s.remove(%s) = %d\n", dev->driver->name,
@@ -140,7 +146,7 @@ static void nvdimm_bus_shutdown(struct device *dev)
 
 void nd_device_notify(struct device *dev, enum nvdimm_event event)
 {
-	device_lock(dev);
+	nd_device_lock(dev);
 	if (dev->driver) {
 		struct nd_device_driver *nd_drv;
 
@@ -148,7 +154,7 @@ void nd_device_notify(struct device *dev, enum nvdimm_event event)
 		if (nd_drv->notify)
 			nd_drv->notify(dev, event);
 	}
-	device_unlock(dev);
+	nd_device_unlock(dev);
 }
 EXPORT_SYMBOL(nd_device_notify);
 
@@ -296,7 +302,7 @@ static void nvdimm_bus_release(struct device *dev)
 	kfree(nvdimm_bus);
 }
 
-static bool is_nvdimm_bus(struct device *dev)
+bool is_nvdimm_bus(struct device *dev)
 {
 	return dev->release == nvdimm_bus_release;
 }
@@ -575,9 +581,9 @@ void nd_device_unregister(struct device *dev, enum nd_async_mode mode)
 		 * or otherwise let the async path handle it if the
 		 * unregistration was already queued.
 		 */
-		device_lock(dev);
+		nd_device_lock(dev);
 		killed = kill_device(dev);
-		device_unlock(dev);
+		nd_device_unlock(dev);
 
 		if (!killed)
 			return;
@@ -888,10 +894,10 @@ void wait_nvdimm_bus_probe_idle(struct device *dev)
 		if (nvdimm_bus->probe_active == 0)
 			break;
 		nvdimm_bus_unlock(dev);
-		device_unlock(dev);
+		nd_device_unlock(dev);
 		wait_event(nvdimm_bus->wait,
 				nvdimm_bus->probe_active == 0);
-		device_lock(dev);
+		nd_device_lock(dev);
 		nvdimm_bus_lock(dev);
 	} while (true);
 }
@@ -1107,7 +1113,7 @@ static int __nd_ioctl(struct nvdimm_bus *nvdimm_bus, struct nvdimm *nvdimm,
 		goto out;
 	}
 
-	device_lock(dev);
+	nd_device_lock(dev);
 	nvdimm_bus_lock(dev);
 	rc = nd_cmd_clear_to_send(nvdimm_bus, nvdimm, func, buf);
 	if (rc)
@@ -1129,7 +1135,7 @@ static int __nd_ioctl(struct nvdimm_bus *nvdimm_bus, struct nvdimm *nvdimm,
 
 out_unlock:
 	nvdimm_bus_unlock(dev);
-	device_unlock(dev);
+	nd_device_unlock(dev);
 out:
 	kfree(in_env);
 	kfree(out_env);

drivers/nvdimm/core.c

@@ -246,7 +246,7 @@ static int nd_uuid_parse(struct device *dev, u8 *uuid_out, const char *buf,
  *
  * Enforce that uuids can only be changed while the device is disabled
  * (driver detached)
- * LOCKING: expects device_lock() is held on entry
+ * LOCKING: expects nd_device_lock() is held on entry
  */
 int nd_uuid_store(struct device *dev, u8 **uuid_out, const char *buf,
 		size_t len)
@@ -347,15 +347,15 @@ static DEVICE_ATTR_RO(provider);
 
 static int flush_namespaces(struct device *dev, void *data)
 {
-	device_lock(dev);
-	device_unlock(dev);
+	nd_device_lock(dev);
+	nd_device_unlock(dev);
 	return 0;
 }
 
 static int flush_regions_dimms(struct device *dev, void *data)
 {
-	device_lock(dev);
-	device_unlock(dev);
+	nd_device_lock(dev);
+	nd_device_unlock(dev);
 	device_for_each_child(dev, NULL, flush_namespaces);
 	return 0;
 }

drivers/nvdimm/dimm_devs.c

@@ -484,12 +484,12 @@ static ssize_t security_store(struct device *dev,
 	 * done while probing is idle and the DIMM is not in active use
 	 * in any region.
 	 */
-	device_lock(dev);
+	nd_device_lock(dev);
 	nvdimm_bus_lock(dev);
 	wait_nvdimm_bus_probe_idle(dev);
 	rc = __security_store(dev, buf, len);
 	nvdimm_bus_unlock(dev);
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	return rc;
 }

drivers/nvdimm/namespace_devs.c

@@ -410,7 +410,7 @@ static ssize_t alt_name_store(struct device *dev,
 	struct nd_region *nd_region = to_nd_region(dev->parent);
 	ssize_t rc;
 
-	device_lock(dev);
+	nd_device_lock(dev);
 	nvdimm_bus_lock(dev);
 	wait_nvdimm_bus_probe_idle(dev);
 	rc = __alt_name_store(dev, buf, len);
@@ -418,7 +418,7 @@ static ssize_t alt_name_store(struct device *dev,
 		rc = nd_namespace_label_update(nd_region, dev);
 	dev_dbg(dev, "%s(%zd)\n", rc < 0 ? "fail " : "", rc);
 	nvdimm_bus_unlock(dev);
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	return rc < 0 ? rc : len;
 }
@@ -1077,7 +1077,7 @@ static ssize_t size_store(struct device *dev,
 	if (rc)
 		return rc;
 
-	device_lock(dev);
+	nd_device_lock(dev);
 	nvdimm_bus_lock(dev);
 	wait_nvdimm_bus_probe_idle(dev);
 	rc = __size_store(dev, val);
@@ -1103,7 +1103,7 @@ static ssize_t size_store(struct device *dev,
 	dev_dbg(dev, "%llx %s (%d)\n", val, rc < 0 ? "fail" : "success", rc);
 
 	nvdimm_bus_unlock(dev);
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	return rc < 0 ? rc : len;
 }
@@ -1286,7 +1286,7 @@ static ssize_t uuid_store(struct device *dev,
 	} else
 		return -ENXIO;
 
-	device_lock(dev);
+	nd_device_lock(dev);
 	nvdimm_bus_lock(dev);
 	wait_nvdimm_bus_probe_idle(dev);
 	if (to_ndns(dev)->claim)
@@ -1302,7 +1302,7 @@ static ssize_t uuid_store(struct device *dev,
 	dev_dbg(dev, "result: %zd wrote: %s%s", rc, buf,
 			buf[len - 1] == '\n' ? "" : "\n");
 	nvdimm_bus_unlock(dev);
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	return rc < 0 ? rc : len;
 }
@@ -1376,7 +1376,7 @@ static ssize_t sector_size_store(struct device *dev,
 	} else
 		return -ENXIO;
 
-	device_lock(dev);
+	nd_device_lock(dev);
 	nvdimm_bus_lock(dev);
 	if (to_ndns(dev)->claim)
 		rc = -EBUSY;
@@ -1387,7 +1387,7 @@ static ssize_t sector_size_store(struct device *dev,
 	dev_dbg(dev, "result: %zd %s: %s%s", rc, rc < 0 ? "tried" : "wrote",
 			buf, buf[len - 1] == '\n' ? "" : "\n");
 	nvdimm_bus_unlock(dev);
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	return rc ? rc : len;
 }
@@ -1502,9 +1502,9 @@ static ssize_t holder_show(struct device *dev,
 	struct nd_namespace_common *ndns = to_ndns(dev);
 	ssize_t rc;
 
-	device_lock(dev);
+	nd_device_lock(dev);
 	rc = sprintf(buf, "%s\n", ndns->claim ? dev_name(ndns->claim) : "");
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	return rc;
 }
@@ -1541,7 +1541,7 @@ static ssize_t holder_class_store(struct device *dev,
 	struct nd_region *nd_region = to_nd_region(dev->parent);
 	ssize_t rc;
 
-	device_lock(dev);
+	nd_device_lock(dev);
 	nvdimm_bus_lock(dev);
 	wait_nvdimm_bus_probe_idle(dev);
 	rc = __holder_class_store(dev, buf);
@@ -1549,7 +1549,7 @@ static ssize_t holder_class_store(struct device *dev,
 		rc = nd_namespace_label_update(nd_region, dev);
 	dev_dbg(dev, "%s(%zd)\n", rc < 0 ? "fail " : "", rc);
 	nvdimm_bus_unlock(dev);
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	return rc < 0 ? rc : len;
 }
@@ -1560,7 +1560,7 @@ static ssize_t holder_class_show(struct device *dev,
 	struct nd_namespace_common *ndns = to_ndns(dev);
 	ssize_t rc;
 
-	device_lock(dev);
+	nd_device_lock(dev);
 	if (ndns->claim_class == NVDIMM_CCLASS_NONE)
 		rc = sprintf(buf, "\n");
 	else if ((ndns->claim_class == NVDIMM_CCLASS_BTT) ||
@@ -1572,7 +1572,7 @@ static ssize_t holder_class_show(struct device *dev,
 		rc = sprintf(buf, "dax\n");
 	else
 		rc = sprintf(buf, "<unknown>\n");
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	return rc;
 }
@@ -1586,7 +1586,7 @@ static ssize_t mode_show(struct device *dev,
 	char *mode;
 	ssize_t rc;
 
-	device_lock(dev);
+	nd_device_lock(dev);
 	claim = ndns->claim;
 	if (claim && is_nd_btt(claim))
 		mode = "safe";
@@ -1599,7 +1599,7 @@ static ssize_t mode_show(struct device *dev,
 	else
 		mode = "raw";
 	rc = sprintf(buf, "%s\n", mode);
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	return rc;
 }
@@ -1703,8 +1703,8 @@ struct nd_namespace_common *nvdimm_namespace_common_probe(struct device *dev)
 		 * Flush any in-progess probes / removals in the driver
 		 * for the raw personality of this namespace.
 		 */
-		device_lock(&ndns->dev);
-		device_unlock(&ndns->dev);
+		nd_device_lock(&ndns->dev);
+		nd_device_unlock(&ndns->dev);
 		if (ndns->dev.driver) {
 			dev_dbg(&ndns->dev, "is active, can't bind %s\n",
 					dev_name(dev));

drivers/nvdimm/nd-core.h

@@ -9,6 +9,7 @@
 #include <linux/sizes.h>
 #include <linux/mutex.h>
 #include <linux/nd.h>
+#include "nd.h"
 
 extern struct list_head nvdimm_bus_list;
 extern struct mutex nvdimm_bus_list_mutex;
@@ -182,4 +183,71 @@ ssize_t nd_namespace_store(struct device *dev,
 		struct nd_namespace_common **_ndns, const char *buf,
 		size_t len);
 struct nd_pfn *to_nd_pfn_safe(struct device *dev);
+bool is_nvdimm_bus(struct device *dev);
+
+#ifdef CONFIG_PROVE_LOCKING
+extern struct class *nd_class;
+
+enum {
+	LOCK_BUS,
+	LOCK_NDCTL,
+	LOCK_REGION,
+	LOCK_DIMM = LOCK_REGION,
+	LOCK_NAMESPACE,
+	LOCK_CLAIM,
+};
+
+static inline void debug_nvdimm_lock(struct device *dev)
+{
+	if (is_nd_region(dev))
+		mutex_lock_nested(&dev->lockdep_mutex, LOCK_REGION);
+	else if (is_nvdimm(dev))
+		mutex_lock_nested(&dev->lockdep_mutex, LOCK_DIMM);
+	else if (is_nd_btt(dev) || is_nd_pfn(dev) || is_nd_dax(dev))
+		mutex_lock_nested(&dev->lockdep_mutex, LOCK_CLAIM);
+	else if (dev->parent && (is_nd_region(dev->parent)))
+		mutex_lock_nested(&dev->lockdep_mutex, LOCK_NAMESPACE);
+	else if (is_nvdimm_bus(dev))
+		mutex_lock_nested(&dev->lockdep_mutex, LOCK_BUS);
+	else if (dev->class && dev->class == nd_class)
+		mutex_lock_nested(&dev->lockdep_mutex, LOCK_NDCTL);
+	else
+		dev_WARN(dev, "unknown lock level\n");
+}
+
+static inline void debug_nvdimm_unlock(struct device *dev)
+{
+	mutex_unlock(&dev->lockdep_mutex);
+}
+
+static inline void nd_device_lock(struct device *dev)
+{
+	device_lock(dev);
+	debug_nvdimm_lock(dev);
+}
+
+static inline void nd_device_unlock(struct device *dev)
+{
+	debug_nvdimm_unlock(dev);
+	device_unlock(dev);
+}
+#else
+static inline void nd_device_lock(struct device *dev)
+{
+	device_lock(dev);
+}
+
+static inline void nd_device_unlock(struct device *dev)
+{
+	device_unlock(dev);
+}
+
+static inline void debug_nvdimm_lock(struct device *dev)
+{
+}
+
+static inline void debug_nvdimm_unlock(struct device *dev)
+{
+}
+#endif
 #endif /* __ND_CORE_H__ */

drivers/nvdimm/pfn_devs.c

@@ -67,7 +67,7 @@ static ssize_t mode_store(struct device *dev,
 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
 	ssize_t rc = 0;
 
-	device_lock(dev);
+	nd_device_lock(dev);
 	nvdimm_bus_lock(dev);
 	if (dev->driver)
 		rc = -EBUSY;
@@ -89,7 +89,7 @@ static ssize_t mode_store(struct device *dev,
 	dev_dbg(dev, "result: %zd wrote: %s%s", rc, buf,
 			buf[len - 1] == '\n' ? "" : "\n");
 	nvdimm_bus_unlock(dev);
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	return rc ? rc : len;
 }
@@ -132,14 +132,14 @@ static ssize_t align_store(struct device *dev,
 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
 	ssize_t rc;
 
-	device_lock(dev);
+	nd_device_lock(dev);
 	nvdimm_bus_lock(dev);
 	rc = nd_size_select_store(dev, buf, &nd_pfn->align,
 			nd_pfn_supported_alignments());
 	dev_dbg(dev, "result: %zd wrote: %s%s", rc, buf,
 			buf[len - 1] == '\n' ? "" : "\n");
 	nvdimm_bus_unlock(dev);
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	return rc ? rc : len;
 }
@@ -161,11 +161,11 @@ static ssize_t uuid_store(struct device *dev,
 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
 	ssize_t rc;
 
-	device_lock(dev);
+	nd_device_lock(dev);
 	rc = nd_uuid_store(dev, &nd_pfn->uuid, buf, len);
 	dev_dbg(dev, "result: %zd wrote: %s%s", rc, buf,
 			buf[len - 1] == '\n' ? "" : "\n");
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	return rc ? rc : len;
 }
@@ -190,13 +190,13 @@ static ssize_t namespace_store(struct device *dev,
 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
 	ssize_t rc;
 
-	device_lock(dev);
+	nd_device_lock(dev);
 	nvdimm_bus_lock(dev);
 	rc = nd_namespace_store(dev, &nd_pfn->ndns, buf, len);
 	dev_dbg(dev, "result: %zd wrote: %s%s", rc, buf,
 			buf[len - 1] == '\n' ? "" : "\n");
 	nvdimm_bus_unlock(dev);
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	return rc;
 }
@@ -208,7 +208,7 @@ static ssize_t resource_show(struct device *dev,
 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
 	ssize_t rc;
 
-	device_lock(dev);
+	nd_device_lock(dev);
 	if (dev->driver) {
 		struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
 		u64 offset = __le64_to_cpu(pfn_sb->dataoff);
@@ -222,7 +222,7 @@ static ssize_t resource_show(struct device *dev,
 		/* no address to convey if the pfn instance is disabled */
 		rc = -ENXIO;
 	}
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	return rc;
 }
@@ -234,7 +234,7 @@ static ssize_t size_show(struct device *dev,
 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
 	ssize_t rc;
 
-	device_lock(dev);
+	nd_device_lock(dev);
 	if (dev->driver) {
 		struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
 		u64 offset = __le64_to_cpu(pfn_sb->dataoff);
@@ -250,7 +250,7 @@ static ssize_t size_show(struct device *dev,
 		/* no size to convey if the pfn instance is disabled */
 		rc = -ENXIO;
 	}
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	return rc;
 }

drivers/nvdimm/pmem.c

@@ -520,8 +520,8 @@ static int nd_pmem_remove(struct device *dev)
 		nvdimm_namespace_detach_btt(to_nd_btt(dev));
 	else {
 		/*
-		 * Note, this assumes device_lock() context to not race
-		 * nd_pmem_notify()
+		 * Note, this assumes nd_device_lock() context to not
+		 * race nd_pmem_notify()
 		 */
 		sysfs_put(pmem->bb_state);
 		pmem->bb_state = NULL;

drivers/nvdimm/region.c

@@ -102,7 +102,7 @@ static int nd_region_remove(struct device *dev)
 	nvdimm_bus_unlock(dev);
 
 	/*
-	 * Note, this assumes device_lock() context to not race
+	 * Note, this assumes nd_device_lock() context to not race
 	 * nd_region_notify()
 	 */
 	sysfs_put(nd_region->bb_state);

drivers/nvdimm/region_devs.c

@@ -329,7 +329,7 @@ static ssize_t set_cookie_show(struct device *dev,
 	 * the v1.1 namespace label cookie definition. To read all this
 	 * data we need to wait for probing to settle.
 	 */
-	device_lock(dev);
+	nd_device_lock(dev);
 	nvdimm_bus_lock(dev);
 	wait_nvdimm_bus_probe_idle(dev);
 	if (nd_region->ndr_mappings) {
@@ -346,7 +346,7 @@ static ssize_t set_cookie_show(struct device *dev,
 		}
 	}
 	nvdimm_bus_unlock(dev);
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	if (rc)
 		return rc;
@@ -422,12 +422,12 @@ static ssize_t available_size_show(struct device *dev,
 	 * memory nvdimm_bus_lock() is dropped, but that's userspace's
 	 * problem to not race itself.
 	 */
-	device_lock(dev);
+	nd_device_lock(dev);
 	nvdimm_bus_lock(dev);
 	wait_nvdimm_bus_probe_idle(dev);
 	available = nd_region_available_dpa(nd_region);
 	nvdimm_bus_unlock(dev);
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	return sprintf(buf, "%llu\n", available);
 }
@@ -439,12 +439,12 @@ static ssize_t max_available_extent_show(struct device *dev,
 	struct nd_region *nd_region = to_nd_region(dev);
 	unsigned long long available = 0;
 
-	device_lock(dev);
+	nd_device_lock(dev);
 	nvdimm_bus_lock(dev);
 	wait_nvdimm_bus_probe_idle(dev);
 	available = nd_region_allocatable_dpa(nd_region);
 	nvdimm_bus_unlock(dev);
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	return sprintf(buf, "%llu\n", available);
 }
@@ -563,12 +563,12 @@ static ssize_t region_badblocks_show(struct device *dev,
 	struct nd_region *nd_region = to_nd_region(dev);
 	ssize_t rc;
 
-	device_lock(dev);
+	nd_device_lock(dev);
 	if (dev->driver)
 		rc = badblocks_show(&nd_region->bb, buf, 0);
 	else
 		rc = -ENXIO;
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	return rc;
 }

include/linux/device.h

@@ -909,6 +909,8 @@ struct dev_links_info {
  * 		This identifies the device type and carries type-specific
  * 		information.
  * @mutex:	Mutex to synchronize calls to its driver.
+ * @lockdep_mutex: An optional debug lock that a subsystem can use as a
+ * 		peer lock to gain localized lockdep coverage of the device_lock.
  * @bus:	Type of bus device is on.
  * @driver:	Which driver has allocated this
  * @platform_data: Platform data specific to the device.
@@ -991,6 +993,9 @@ struct device {
 					   core doesn't touch it */
 	void		*driver_data;	/* Driver data, set and get with
 					   dev_set_drvdata/dev_get_drvdata */
+#ifdef CONFIG_PROVE_LOCKING
+	struct mutex		lockdep_mutex;
+#endif
 	struct mutex		mutex;	/* mutex to synchronize calls to
 					 * its driver.
 					 */