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
diff --git a/drivers/nvdimm/nd-core.h b/drivers/nvdimm/nd-core.h
index 6cd4705..0ac52b6 100644
--- a/drivers/nvdimm/nd-core.h
+++ b/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__ */
