[PATCH] lockdep: prove rwsem locking correctness

Use the lock validator framework to prove rwsem locking correctness.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 31 insertions, 3 deletions

diff --git a/include/asm-s390/rwsem.h b/include/asm-s390/rwsem.h
index 0422a085dd56..13ec16965150 100644
--- a/include/asm-s390/rwsem.h
+++ b/include/asm-s390/rwsem.h
@@ -61,6 +61,9 @@ struct rw_semaphore {
         signed long             count;
         spinlock_t              wait_lock;
         struct list_head        wait_list;
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+        struct lockdep_map      dep_map;
+#endif
 };
 
 #ifndef __s390x__
@@ -80,8 +83,16 @@ struct rw_semaphore {
 /*
  * initialisation
  */
+
+#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, LIST_HEAD_INIT((name).wait_list) }
+{ RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) \
+  __RWSEM_DEP_MAP_INIT(name) }
 
 #define DECLARE_RWSEM(name) \
         struct rw_semaphore name = __RWSEM_INITIALIZER(name)
@@ -93,6 +104,17 @@ static inline void init_rwsem(struct rw_semaphore *sem)
         INIT_LIST_HEAD(&sem->wait_list);
 }
 
+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
  */
@@ -155,7 +177,7 @@ static inline int __down_read_trylock(struct rw_semaphore *sem)
 /*
  * lock for writing
  */
-static inline void __down_write(struct rw_semaphore *sem)
+static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
 {
         signed long old, new, tmp;
 
@@ -181,6 +203,11 @@ static inline void __down_write(struct rw_semaphore *sem)
                 rwsem_down_write_failed(sem);
 }
 
+static inline void __down_write(struct rw_semaphore *sem)
+{
+        __down_write_nested(sem, 0);
+}
+
 /*
  * trylock for writing -- returns 1 if successful, 0 if contention
  */
diff --git a/include/asm-s390/semaphore.h b/include/asm-s390/semaphore.h
index 702cf436698c..32cdc69f39f4 100644
--- a/include/asm-s390/semaphore.h
+++ b/include/asm-s390/semaphore.h
@@ -37,7 +37,8 @@ struct semaphore {
 
 static inline void sema_init (struct semaphore *sem, int val)
 {
-        *sem = (struct semaphore) __SEMAPHORE_INITIALIZER((*sem),val);
+        atomic_set(&sem->count, val);
+        init_waitqueue_head(&sem->wait);
 }
 
 static inline void init_MUTEX (struct semaphore *sem)