[PATCH RFC 06/33] locking/mutex: Annotate struct mutex and mutex functions

[Bart Van Assche <bvanassche@acm.org>]

Inform the Clang thread-safety analyzer about mutex operations and also
about the meaning of the return value of the functions that operate on
mutexes.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 include/linux/mutex.h       | 46 +++++++++++++++++++++++--------------
 include/linux/mutex_types.h |  5 ++--
 kernel/locking/mutex.c      | 12 ++++++++++
 3 files changed, 44 insertions(+), 19 deletions(-)

diff --git a/include/linux/mutex.h b/include/linux/mutex.h
index 6c0a8a843a29..b7669baeffe9 100644
--- a/include/linux/mutex.h
+++ b/include/linux/mutex.h
@@ -21,6 +21,7 @@
 #include <linux/debug_locks.h>
 #include <linux/cleanup.h>
 #include <linux/mutex_types.h>
+#include <linux/thread_safety.h>
 
 struct device;
 
@@ -154,14 +155,18 @@ static inline int __devm_mutex_init(struct device *dev, struct mutex *lock)
  * Also see Documentation/locking/mutex-design.rst.
  */
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
-extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass);
-extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock);
+void mutex_lock_nested(struct mutex *lock, unsigned int subclass) ACQUIRE(*lock);
+void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock)
+	ACQUIRE(*lock);
 
 extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock,
-					unsigned int subclass);
+					unsigned int subclass)
+	TRY_ACQUIRE(0, *lock);
 extern int __must_check mutex_lock_killable_nested(struct mutex *lock,
-					unsigned int subclass);
-extern void mutex_lock_io_nested(struct mutex *lock, unsigned int subclass);
+					unsigned int subclass)
+	TRY_ACQUIRE(0, *lock);
+extern void mutex_lock_io_nested(struct mutex *lock, unsigned int subclass)
+	ACQUIRE(*lock);
 
 #define mutex_lock(lock) mutex_lock_nested(lock, 0)
 #define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0)
@@ -175,10 +180,11 @@ do {									\
 } while (0)
 
 #else
-extern void mutex_lock(struct mutex *lock);
-extern int __must_check mutex_lock_interruptible(struct mutex *lock);
-extern int __must_check mutex_lock_killable(struct mutex *lock);
-extern void mutex_lock_io(struct mutex *lock);
+void mutex_lock(struct mutex *lock) ACQUIRE(*lock);
+int __must_check mutex_lock_interruptible(struct mutex *lock)
+	TRY_ACQUIRE(0, *lock);
+int __must_check mutex_lock_killable(struct mutex *lock) TRY_ACQUIRE(0, *lock);
+void mutex_lock_io(struct mutex *lock) ACQUIRE(*lock);
 
 # define mutex_lock_nested(lock, subclass) mutex_lock(lock)
 # define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock)
@@ -193,13 +199,19 @@ extern void mutex_lock_io(struct mutex *lock);
  *
  * Returns 1 if the mutex has been acquired successfully, and 0 on contention.
  */
-extern int mutex_trylock(struct mutex *lock);
-extern void mutex_unlock(struct mutex *lock);
-
-bool atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);
-
-DEFINE_GUARD(mutex, struct mutex *, mutex_lock(_T), mutex_unlock(_T))
-DEFINE_GUARD_COND(mutex, _try, mutex_trylock(_T))
-DEFINE_GUARD_COND(mutex, _intr, mutex_lock_interruptible(_T) == 0)
+int mutex_trylock(struct mutex *lock) TRY_ACQUIRE(1, *lock);
+void mutex_unlock(struct mutex *lock) RELEASE(*lock);
+
+bool atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock)
+	TRY_ACQUIRE(true, *lock);
+
+DEFINE_GUARD_ATTR(mutex, struct mutex *,
+		  mutex_lock(_T),
+		  ASSERT_CAPABILITY(*_T) NO_THREAD_SAFETY_ANALYSIS,
+		  mutex_unlock(_T))
+DEFINE_GUARD_COND_ATTR(mutex, _try, mutex_trylock(_T),
+		       ASSERT_CAPABILITY(*_T) NO_THREAD_SAFETY_ANALYSIS)
+DEFINE_GUARD_COND_ATTR(mutex, _intr, mutex_lock_interruptible(_T) == 0,
+		       ASSERT_CAPABILITY(*_T) NO_THREAD_SAFETY_ANALYSIS)
 
 #endif /* __LINUX_MUTEX_H */
diff --git a/include/linux/mutex_types.h b/include/linux/mutex_types.h
index fdf7f515fde8..59469956426a 100644
--- a/include/linux/mutex_types.h
+++ b/include/linux/mutex_types.h
@@ -6,6 +6,7 @@
 #include <linux/lockdep_types.h>
 #include <linux/osq_lock.h>
 #include <linux/spinlock_types.h>
+#include <linux/thread_safety.h>
 #include <linux/types.h>
 
 #ifndef CONFIG_PREEMPT_RT
@@ -38,7 +39,7 @@
  * - detects multi-task circular deadlocks and prints out all affected
  *   locks and tasks (and only those tasks)
  */
-struct mutex {
+struct CAPABILITY("mutex") mutex {
 	atomic_long_t		owner;
 	raw_spinlock_t		wait_lock;
 #ifdef CONFIG_MUTEX_SPIN_ON_OWNER
@@ -59,7 +60,7 @@ struct mutex {
  */
 #include <linux/rtmutex.h>
 
-struct mutex {
+struct CAPABILITY("mutex") mutex {
 	struct rt_mutex_base	rtmutex;
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 	struct lockdep_map	dep_map;
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index 0af175f5f031..e44becde2610 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -254,6 +254,7 @@ static void __sched __mutex_lock_slowpath(struct mutex *lock);
  * This function is similar to (but not equivalent to) down().
  */
 void __sched mutex_lock(struct mutex *lock)
+	NO_THREAD_SAFETY_ANALYSIS
 {
 	might_sleep();
 
@@ -515,6 +516,7 @@ static noinline void __sched __mutex_unlock_slowpath(struct mutex *lock, unsigne
  * This function is similar to (but not equivalent to) up().
  */
 void __sched mutex_unlock(struct mutex *lock)
+	NO_THREAD_SAFETY_ANALYSIS
 {
 #ifndef CONFIG_DEBUG_LOCK_ALLOC
 	if (__mutex_unlock_fast(lock))
@@ -536,6 +538,7 @@ EXPORT_SYMBOL(mutex_unlock);
  * of a unlocked mutex is not allowed.
  */
 void __sched ww_mutex_unlock(struct ww_mutex *lock)
+	NO_THREAD_SAFETY_ANALYSIS
 {
 	__ww_mutex_unlock(lock);
 	mutex_unlock(&lock->base);
@@ -751,6 +754,7 @@ __ww_mutex_lock(struct mutex *lock, unsigned int state, unsigned int subclass,
  * A mutex acquired with this function must be released with ww_mutex_unlock.
  */
 int ww_mutex_trylock(struct ww_mutex *ww, struct ww_acquire_ctx *ww_ctx)
+	NO_THREAD_SAFETY_ANALYSIS
 {
 	if (!ww_ctx)
 		return mutex_trylock(&ww->base);
@@ -778,6 +782,7 @@ EXPORT_SYMBOL(ww_mutex_trylock);
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 void __sched
 mutex_lock_nested(struct mutex *lock, unsigned int subclass)
+	NO_THREAD_SAFETY_ANALYSIS
 {
 	__mutex_lock(lock, TASK_UNINTERRUPTIBLE, subclass, NULL, _RET_IP_);
 }
@@ -786,6 +791,7 @@ EXPORT_SYMBOL_GPL(mutex_lock_nested);
 
 void __sched
 _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest)
+	NO_THREAD_SAFETY_ANALYSIS
 {
 	__mutex_lock(lock, TASK_UNINTERRUPTIBLE, 0, nest, _RET_IP_);
 }
@@ -807,6 +813,7 @@ EXPORT_SYMBOL_GPL(mutex_lock_interruptible_nested);
 
 void __sched
 mutex_lock_io_nested(struct mutex *lock, unsigned int subclass)
+	NO_THREAD_SAFETY_ANALYSIS
 {
 	int token;
 
@@ -957,6 +964,7 @@ __mutex_lock_interruptible_slowpath(struct mutex *lock);
  * signal arrived.
  */
 int __sched mutex_lock_interruptible(struct mutex *lock)
+	NO_THREAD_SAFETY_ANALYSIS
 {
 	might_sleep();
 
@@ -981,6 +989,7 @@ EXPORT_SYMBOL(mutex_lock_interruptible);
  * fatal signal arrived.
  */
 int __sched mutex_lock_killable(struct mutex *lock)
+	NO_THREAD_SAFETY_ANALYSIS
 {
 	might_sleep();
 
@@ -1061,6 +1070,7 @@ __ww_mutex_lock_interruptible_slowpath(struct ww_mutex *lock,
  * mutex must be released by the same task that acquired it.
  */
 int __sched mutex_trylock(struct mutex *lock)
+	NO_THREAD_SAFETY_ANALYSIS
 {
 	bool locked;
 
@@ -1077,6 +1087,7 @@ EXPORT_SYMBOL(mutex_trylock);
 #ifndef CONFIG_DEBUG_LOCK_ALLOC
 int __sched
 ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
+	NO_THREAD_SAFETY_ANALYSIS
 {
 	might_sleep();
 
@@ -1092,6 +1103,7 @@ EXPORT_SYMBOL(ww_mutex_lock);
 
 int __sched
 ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
+	NO_THREAD_SAFETY_ANALYSIS
 {
 	might_sleep();