linux-kernel - [PATCH 3/9] locking/mutex: Mark devm_mutex_init() as __must

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20250716144818.47650-4-boqun.feng@gmail.com>
Date: Wed, 16 Jul 2025 07:48:12 -0700
From: Boqun Feng <boqun.feng@...il.com>
To: Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>
Cc: "Will Deacon" <will@...nel.org>,
	"Waiman Long" <longman@...hat.com>,
	Miguel Ojeda <ojeda@...nel.org>,
	Alice Ryhl <aliceryhl@...gle.com>,
	linux-kernel@...r.kernel.org,
	rust-for-linux@...r.kernel.org,
	Breno Leitao <leitao@...ian.org>,
	"Paul E. McKenney" <paulmck@...nel.org>,
	Thomas Weißschuh <linux@...ssschuh.net>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>,
	Boqun Feng <boqun.feng@...il.com>
Subject: [PATCH 3/9] locking/mutex: Mark devm_mutex_init() as __must_check

From: Thomas Weißschuh <linux@...ssschuh.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@...radead.org>
Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Signed-off-by: Boqun Feng <boqun.feng@...il.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)