[patch] locking, rwsem: Add missing __init_rwsem() for PREEMPT_RT

[Mike Galbraith]

730633f0b7f95 became the first direct caller of __init_rwsem() vs the
usual init_rwsem(), exposing PREEMPT_RT's lack thereof.  Add it.

Signed-off-by: Mike Galbraith <efault@xxxxxx>
---
 include/linux/rwsem.h |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

--- a/include/linux/rwsem.h
+++ b/include/linux/rwsem.h
@@ -152,12 +152,18 @@ static inline void  __rwsem_init(struct
 }
 #endif

+static inline void __init_rwsem(struct rw_semaphore *sem, const char *name,
+				struct lock_class_key *key)
+{
+	init_rwbase_rt(&(sem)->rwbase);
+	__rwsem_init(sem, name, key);
+}
+
 #define init_rwsem(sem)						\
 do {								\
 	static struct lock_class_key __key;			\
 								\
-	init_rwbase_rt(&(sem)->rwbase);			\
-	__rwsem_init((sem), #sem, &__key);			\
+	__init_rwsem((sem), #sem, &__key);			\
 } while (0)

 static __always_inline int rwsem_is_locked(struct rw_semaphore *sem)