Using of devm API leads to a certain order of releasing resources. So all dependent resources which are not devm-wrapped should be deleted with respect to devm-release order. Mutex is one of such objects that often is bound to other resources and has no own devm wrapping. Since mutex_destroy() actually does nothing in non-debug builds frequently calling mutex_destroy() is just ignored which is safe for now but wrong formally and can lead to a problem if mutex_destroy() will be extended so introduce devm_mutex_init() Signed-off-by: George Stark <gnstark@xxxxxxxxxxxxxxxxx> Suggested by-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx> --- include/linux/mutex.h | 27 +++++++++++++++++++++++++++ kernel/locking/mutex-debug.c | 11 +++++++++++ 2 files changed, 38 insertions(+) diff --git a/include/linux/mutex.h b/include/linux/mutex.h index 67edc4ca2bee..f57e005ded24 100644 --- a/include/linux/mutex.h +++ b/include/linux/mutex.h @@ -22,6 +22,8 @@ #include <linux/cleanup.h> #include <linux/mutex_types.h> +struct device; + #ifdef CONFIG_DEBUG_LOCK_ALLOC # define __DEP_MAP_MUTEX_INITIALIZER(lockname) \ , .dep_map = { \ @@ -117,6 +119,31 @@ do { \ } while (0) #endif /* CONFIG_PREEMPT_RT */ +#ifdef CONFIG_DEBUG_MUTEXES + +int __devm_mutex_init(struct device *dev, struct mutex *lock); + +#else + +static inline int __devm_mutex_init(struct device *dev, struct mutex *lock) +{ + /* + * When CONFIG_DEBUG_MUTEXES is off mutex_destroy is just a nop so + * no really need to register it in devm subsystem. + */ + return 0; +} + +#endif + +#define devm_mutex_init(dev, mutex) \ +({ \ + typeof(mutex) mutex_ = (mutex); \ + \ + mutex_init(mutex_); \ + __devm_mutex_init(dev, mutex_); \ +}) + /* * See kernel/locking/mutex.c for detailed documentation of these APIs. * Also see Documentation/locking/mutex-design.rst. diff --git a/kernel/locking/mutex-debug.c b/kernel/locking/mutex-debug.c index bc8abb8549d2..6aa77e3dc82e 100644 --- a/kernel/locking/mutex-debug.c +++ b/kernel/locking/mutex-debug.c @@ -19,6 +19,7 @@ #include <linux/kallsyms.h> #include <linux/interrupt.h> #include <linux/debug_locks.h> +#include <linux/device.h> #include "mutex.h" @@ -89,6 +90,16 @@ void debug_mutex_init(struct mutex *lock, const char *name, lock->magic = lock; } +static void devm_mutex_release(void *res) +{ + mutex_destroy(res); +} + +int __devm_mutex_init(struct device *dev, struct mutex *lock) +{ + return devm_add_action_or_reset(dev, devm_mutex_release, lock); +} + /*** * mutex_destroy - mark a mutex unusable * @lock: the mutex to be destroyed -- 2.25.1