From: Thomas Weißschuh <linux@weissschuh.net>
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 <peterz@infradead.org>
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
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 a039fa8c1780..00afd341d293 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.
--
2.39.5 (Apple Git-154)