[PATCH 2/3] locking/rwsem: provide a lock guard for down_read_nested()

[Bartosz Golaszewski <brgl@xxxxxxxx>]

From: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>

This adds a lock guard for taking an RW semaphore for reading in nested
context. It takes the nesting depth as a second argument.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
---
 include/linux/rwsem.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h
index 9c29689ff505..298f5e60d30c 100644
--- a/include/linux/rwsem.h
+++ b/include/linux/rwsem.h
@@ -258,4 +258,10 @@ extern void up_read_non_owner(struct rw_semaphore *sem);
 # define up_read_non_owner(sem)			up_read(sem)
 #endif
 
+DEFINE_LOCK_GUARD_ARGS(rwsem_read_nested,
+		       struct rw_semaphore *,
+		       down_read_nested(_T, subclass),
+		       up_read(_T),
+		       int subclass);
+
 #endif /* _LINUX_RWSEM_H */
-- 
2.40.1