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 <redacted>
---
  include/linux/mutex.h        | 23 +++++++++++++++++++++++
  kernel/locking/mutex-debug.c | 22 ++++++++++++++++++++++
  2 files changed, 45 insertions(+)

diff --git a/include/linux/mutex.h b/include/linux/mutex.h
index a33aa9eb9fc3..ebd03ff1ef66 100644
--- a/include/linux/mutex.h
+++ b/include/linux/mutex.h

@@ -21,6 +21,8 @@
  #include <linux/debug_locks.h>
  #include <linux/cleanup.h>
  
+struct device;
+
  #ifdef CONFIG_DEBUG_LOCK_ALLOC
  # define __DEP_MAP_MUTEX_INITIALIZER(lockname)			\
  		, .dep_map = {					\

@@ -127,6 +129,20 @@ extern void __mutex_init(struct mutex *lock, const char *name,
   */
  extern bool mutex_is_locked(struct mutex *lock);
  
+#ifdef CONFIG_DEBUG_MUTEXES
+
+int devm_mutex_init(struct device *dev, struct mutex *lock);

+
+#endif
+
  #else /* !CONFIG_PREEMPT_RT */
  /*
   * Preempt-RT variant based on rtmutexes.

@@ -169,6 +185,13 @@ do {							\
  							\
  	__mutex_init((mutex), #mutex, &__key);		\
  } while (0)
+
+static inline int devm_mutex_init(struct device *dev, struct mutex *lock)
+{
+	mutex_init(lock);
+	return 0;
+}
+
  #endif /* CONFIG_PREEMPT_RT */
  
  /*

diff --git a/kernel/locking/mutex-debug.c b/kernel/locking/mutex-debug.c
index bc8abb8549d2..c9efab1a8026 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"
  

@@ -104,3 +105,24 @@ void mutex_destroy(struct mutex *lock)
  }
  
  EXPORT_SYMBOL_GPL(mutex_destroy);
+
+static void devm_mutex_release(void *res)
+{
+	mutex_destroy(res);
+}
+
+/**
+ * devm_mutex_init - Resource-managed mutex initialization
+ * @dev:	Device which lifetime mutex is bound to
+ * @lock:	Pointer to a mutex
+ *
+ * Initialize mutex which is automatically destroyed when the driver is detached.
+ *
+ * Returns: 0 on success or a negative error code on failure.
+ */
+int devm_mutex_init(struct device *dev, struct mutex *lock)
+{
+	mutex_init(lock);
+	return devm_add_action_or_reset(dev, devm_mutex_release, lock);
+}
+EXPORT_SYMBOL_GPL(devm_mutex_init);