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

2 files changed, 38 insertions, 14 deletions

diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index 23022cf20d26..f22139458ce1 100644
--- a/drivers/acpi/nfit/core.c
+++ b/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[] = {
diff --git a/drivers/acpi/nfit/nfit.h b/drivers/acpi/nfit/nfit.h
index 6ee2b02af73e..24241941181c 100644
--- a/drivers/acpi/nfit/nfit.h
+++ b/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);