[PATCH v3 1/4] nvdimm: Convert nvdimm_bus guard to class

[Dmitry Ilvokhin <d@ilvokhin.com>]

The nvdimm_bus guard accepts NULL and skips locking when NULL is passed.
Convert from DEFINE_GUARD() to DEFINE_CLASS() + DEFINE_CLASS_IS_GUARD().

This is a preparatory change for making DEFINE_GUARD() constructors
__nonnull(). nvdimm_bus legitimately passes NULL, so it must be adjusted
to avoid a compile error.

No functional change.

Signed-off-by: Dmitry Ilvokhin <d@ilvokhin.com>
---
 drivers/nvdimm/nd.h | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/nvdimm/nd.h b/drivers/nvdimm/nd.h
index b199eea3260e..18b64559664b 100644
--- a/drivers/nvdimm/nd.h
+++ b/drivers/nvdimm/nd.h
@@ -632,8 +632,11 @@ u64 nd_region_interleave_set_cookie(struct nd_region *nd_region,
 u64 nd_region_interleave_set_altcookie(struct nd_region *nd_region);
 void nvdimm_bus_lock(struct device *dev);
 void nvdimm_bus_unlock(struct device *dev);
-DEFINE_GUARD(nvdimm_bus, struct device *,
-	     if (_T) nvdimm_bus_lock(_T), if (_T) nvdimm_bus_unlock(_T));
+DEFINE_CLASS(nvdimm_bus, struct device *,
+	     if (_T) nvdimm_bus_unlock(_T),
+	     ({ if (_T) nvdimm_bus_lock(_T); _T; }),
+	     struct device *_T);
+DEFINE_CLASS_IS_GUARD(nvdimm_bus);
 
 bool is_nvdimm_bus_locked(struct device *dev);
 void nvdimm_check_and_set_ro(struct gendisk *disk);
-- 
2.53.0-Meta