Commit daec29dc authored by Thomas Weißschuh's avatar Thomas Weißschuh Committed by Boqun Feng
Browse files

locking/mutex: Mark devm_mutex_init() as __must_check 



devm_mutex_init() can fail. With CONFIG_DEBUG_MUTEXES=y the mutex will be
marked as unusable and trigger errors on usage.
Enforce all callers check the return value through the compiler.

As devm_mutex_init() itself is a macro, it can not be annotated
directly. Annotate __devm_mutex_init() instead.
Unfortunately __must_check/warn_unused_result don't propagate through
statement expression. So move the statement expression into the argument
list of the call to __devm_mutex_init() through a helper macro.

Suggested-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarThomas Weißschuh <linux@weissschuh.net>
Reviewed-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: default avatarBartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: default avatarBoqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20250617-must_check-devm_mutex_init-v7-3-d9e449f4d224@weissschuh.net
parent 3b07bb90

include/linux/mutex.h

+7 −4
Original line number Diff line number Diff line
@@ -126,11 +126,11 @@ do { \ 


#ifdef CONFIG_DEBUG_MUTEXES



int __devm_mutex_init(struct device *dev, struct mutex *lock);

int __must_check __devm_mutex_init(struct device *dev, struct mutex *lock);



#else



static inline int __devm_mutex_init(struct device *dev, struct mutex *lock)

static inline int __must_check __devm_mutex_init(struct device *dev, struct mutex *lock)

{

	/*

	 * When CONFIG_DEBUG_MUTEXES is off mutex_destroy() is just a nop so
@@ -141,14 +141,17 @@ static inline int __devm_mutex_init(struct device *dev, struct mutex *lock) 


#endif



#define devm_mutex_init(dev, mutex)			\

#define __mutex_init_ret(mutex)				\

({							\

	typeof(mutex) mutex_ = (mutex);			\

							\

	mutex_init(mutex_);				\

	__devm_mutex_init(dev, mutex_);			\

	mutex_;						\

})



#define devm_mutex_init(dev, mutex) \

	__devm_mutex_init(dev, __mutex_init_ret(mutex))



/*

 * See kernel/locking/mutex.c for detailed documentation of these APIs.

 * Also see Documentation/locking/mutex-design.rst.