1 files changed, 52 insertions, 1 deletions

diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h
index efd348fe8ca7..a8afe9cd000c 100644
--- a/include/linux/rwsem.h
+++ b/include/linux/rwsem.h
@@ -11,6 +11,9 @@
 
 #include <linux/types.h>
 #include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+
 #include <asm/system.h>
 #include <asm/atomic.h>
 
@@ -19,9 +22,57 @@ struct rw_semaphore;
 #ifdef CONFIG_RWSEM_GENERIC_SPINLOCK
 #include <linux/rwsem-spinlock.h> /* use a generic implementation */
 #else
-#include <asm/rwsem.h> /* use an arch-specific implementation */
+/* All arch specific implementations share the same struct */
+struct rw_semaphore {
+        long                    count;
+        spinlock_t              wait_lock;
+        struct list_head        wait_list;
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+        struct lockdep_map      dep_map;
+#endif
+};
+
+extern struct rw_semaphore *rwsem_down_read_failed(struct rw_semaphore *sem);
+extern struct rw_semaphore *rwsem_down_write_failed(struct rw_semaphore *sem);
+extern struct rw_semaphore *rwsem_wake(struct rw_semaphore *);
+extern struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem);
+
+/* Include the arch specific part */
+#include <asm/rwsem.h>
+
+/* In all implementations count != 0 means locked */
+static inline int rwsem_is_locked(struct rw_semaphore *sem)
+{
+        return sem->count != 0;
+}
+
+#endif
+
+/* Common initializer macros and functions */
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+# define __RWSEM_DEP_MAP_INIT(lockname) , .dep_map = { .name = #lockname }
+#else
+# define __RWSEM_DEP_MAP_INIT(lockname)
 #endif
 
+#define __RWSEM_INITIALIZER(name) \
+        { RWSEM_UNLOCKED_VALUE, __SPIN_LOCK_UNLOCKED(name.wait_lock),   \
+          LIST_HEAD_INIT((name).wait_list) __RWSEM_DEP_MAP_INIT(name) }
+
+#define DECLARE_RWSEM(name) \
+        struct rw_semaphore name = __RWSEM_INITIALIZER(name)
+
+extern void __init_rwsem(struct rw_semaphore *sem, const char *name,
+                         struct lock_class_key *key);
+
+#define init_rwsem(sem)                                         \
+do {                                                            \
+        static struct lock_class_key __key;                     \
+                                                                \
+        __init_rwsem((sem), #sem, &__key);                      \
+} while (0)
+
 /*
  * lock for reading
  */