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Subject[PATCH 3/3] mutex: Add missing annotations
Sparse reports false warnings and hide real warnings
where mutex_lock() and mutex_unlock() are used within the kernel
An example is within the kernel cgroup files
where the below warnings are found
|warning: context imbalance in cgroup_lock_and_drain_offline()
| - wrong count at exit
|warning: context imbalance in cgroup_procs_write_finish()
|- wrong count at exit
|warning: context imbalance in cgroup_procs_write_start()
|- wrong count at exit.

To fix these,
an __acquires(lock) is added to mutex_lock() declaration
a __releases(lock) to mutex_unlock() declaration

Signed-off-by: Jules Irenge <>
include/linux/mutex.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/mutex.h b/include/linux/mutex.h
index aca8f36dfac9..a8ab4029913e 100644
--- a/include/linux/mutex.h
+++ b/include/linux/mutex.h
@@ -162,7 +162,7 @@ do { \
} while (0)

-extern void mutex_lock(struct mutex *lock);
+extern void mutex_lock(struct mutex *lock) __acquires(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);
@@ -181,7 +181,7 @@ 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);
+extern void mutex_unlock(struct mutex *lock) __releases(lock);

extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);

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