From daec29dcc8731b7596690ab9f647839e4584a86d Mon Sep 17 00:00:00 2001 From: =?utf8?q?Thomas=20Wei=C3=9Fschuh?= Date: Tue, 17 Jun 2025 19:08:14 +0200 Subject: [PATCH] locking/mutex: Mark devm_mutex_init() as __must_check MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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: Peter Zijlstra Signed-off-by: Thomas Weißschuh Reviewed-by: Andy Shevchenko Reviewed-by: Bartosz Golaszewski Signed-off-by: Boqun Feng Link: https://lore.kernel.org/r/20250617-must_check-devm_mutex_init-v7-3-d9e449f4d224@weissschuh.net --- include/linux/mutex.h | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/include/linux/mutex.h b/include/linux/mutex.h index a039fa8c17807..00afd341d293d 100644 --- a/include/linux/mutex.h +++ b/include/linux/mutex.h @@ -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. -- 2.47.2