From 4ea2176dfa714882e88180b474e4cbcd888b70af Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@elte.hu>
Date: Mon, 3 Jul 2006 00:24:53 -0700
Subject: [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>
---
 include/linux/rwsem-spinlock.h | 23 ++++++++++++++--
 include/linux/rwsem.h          | 59 ++++++++++++++++++------------------------
 2 files changed, 46 insertions(+), 36 deletions(-)

(limited to 'include/linux')

diff --git a/include/linux/rwsem-spinlock.h b/include/linux/rwsem-spinlock.h
index d68afcc..ae1fcad 100644
--- a/include/linux/rwsem-spinlock.h
+++ b/include/linux/rwsem-spinlock.h
@@ -32,18 +32,37 @@ struct rw_semaphore {
 	__s32			activity;
 	spinlock_t		wait_lock;
 	struct list_head	wait_list;
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	struct lockdep_map dep_map;
+#endif
 };
 
+#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) \
-{ 0, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) }
+{ 0, 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)
 
-extern void FASTCALL(init_rwsem(struct rw_semaphore *sem));
+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)
+
 extern void FASTCALL(__down_read(struct rw_semaphore *sem));
 extern int FASTCALL(__down_read_trylock(struct rw_semaphore *sem));
 extern void FASTCALL(__down_write(struct rw_semaphore *sem));
+extern void FASTCALL(__down_write_nested(struct rw_semaphore *sem, int subclass));
 extern int FASTCALL(__down_write_trylock(struct rw_semaphore *sem));
 extern void FASTCALL(__up_read(struct rw_semaphore *sem));
 extern void FASTCALL(__up_write(struct rw_semaphore *sem));
diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h
index 9358153..658afb3 100644
--- a/include/linux/rwsem.h
+++ b/include/linux/rwsem.h
@@ -27,64 +27,55 @@ struct rw_semaphore;
 /*
  * lock for reading
  */
-static inline void down_read(struct rw_semaphore *sem)
-{
-	might_sleep();
-	__down_read(sem);
-}
+extern void down_read(struct rw_semaphore *sem);
 
 /*
  * trylock for reading -- returns 1 if successful, 0 if contention
  */
-static inline int down_read_trylock(struct rw_semaphore *sem)
-{
-	int ret;
-	ret = __down_read_trylock(sem);
-	return ret;
-}
+extern int down_read_trylock(struct rw_semaphore *sem);
 
 /*
  * lock for writing
  */
-static inline void down_write(struct rw_semaphore *sem)
-{
-	might_sleep();
-	__down_write(sem);
-}
+extern void down_write(struct rw_semaphore *sem);
 
 /*
  * trylock for writing -- returns 1 if successful, 0 if contention
  */
-static inline int down_write_trylock(struct rw_semaphore *sem)
-{
-	int ret;
-	ret = __down_write_trylock(sem);
-	return ret;
-}
+extern int down_write_trylock(struct rw_semaphore *sem);
 
 /*
  * release a read lock
  */
-static inline void up_read(struct rw_semaphore *sem)
-{
-	__up_read(sem);
-}
+extern void up_read(struct rw_semaphore *sem);
 
 /*
  * release a write lock
  */
-static inline void up_write(struct rw_semaphore *sem)
-{
-	__up_write(sem);
-}
+extern void up_write(struct rw_semaphore *sem);
 
 /*
  * downgrade write lock to read lock
  */
-static inline void downgrade_write(struct rw_semaphore *sem)
-{
-	__downgrade_write(sem);
-}
+extern void downgrade_write(struct rw_semaphore *sem);
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+/*
+ * nested locking:
+ */
+extern void down_read_nested(struct rw_semaphore *sem, int subclass);
+extern void down_write_nested(struct rw_semaphore *sem, int subclass);
+/*
+ * Take/release a lock when not the owner will release it:
+ */
+extern void down_read_non_owner(struct rw_semaphore *sem);
+extern void up_read_non_owner(struct rw_semaphore *sem);
+#else
+# define down_read_nested(sem, subclass)		down_read(sem)
+# define down_write_nested(sem, subclass)	down_write(sem)
+# define down_read_non_owner(sem)		down_read(sem)
+# define up_read_non_owner(sem)			up_read(sem)
+#endif
 
 #endif /* __KERNEL__ */
 #endif /* _LINUX_RWSEM_H */
-- 
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