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().
Suggested-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Signed-off-by: George Stark <gnstark@xxxxxxxxxxxxxxxxx>
Reviewed-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
Reviewed-by: Marek Behún <kabel@xxxxxxxxxx>
Acked-by: Waiman Long <longman@xxxxxxxxxx>
---
include/linux/mutex.h | 27 +++++++++++++++++++++++++++
kernel/locking/mutex-debug.c | 12 ++++++++++++
2 files changed, 39 insertions(+)
diff --git a/include/linux/mutex.h b/include/linux/mutex.h
index 7e208d46ba5b..66dfbbd66310 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 = { \
@@ -121,6 +123,31 @@ 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 the 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..6e6f6071cfa2 100644
--- a/kernel/locking/mutex-debug.c
+++ b/kernel/locking/mutex-debug.c
@@ -12,6 +12,7 @@
*/
#include <linux/mutex.h>
#include <linux/delay.h>
+#include <linux/device.h>
#include <linux/export.h>
#include <linux/poison.h>
#include <linux/sched.h>
@@ -89,6 +90,17 @@ 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);
+}
+EXPORT_SYMBOL_GPL(__devm_mutex_init);
+
/***
* mutex_destroy - mark a mutex unusable
* @lock: the mutex to be destroyed
--
2.25.1
