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 <gnst...@salutedevices.com>
Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu>
---
Hello Christophe. Hope you don't mind I put you SoB tag because you helped alot
to make this patch happen.
include/linux/mutex.h | 13 +++++++++++++
kernel/locking/mutex-debug.c | 22 ++++++++++++++++++++++
2 files changed, 35 insertions(+)
diff --git a/include/linux/mutex.h b/include/linux/mutex.h
index f7611c092db7..9bcf72cb941a 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 = { \
@@ -115,10 +117,21 @@ do {
\
#ifdef CONFIG_DEBUG_MUTEXES
+int devm_mutex_init(struct device *dev, struct mutex *lock);
void mutex_destroy(struct mutex *lock);
#else
+static inline int devm_mutex_init(struct device *dev, struct mutex *lock)
+{
+ /*
+ * since mutex_destroy is nop actually there's no need to register it
+ * in devm subsystem.
+ */
+ mutex_init(lock);
+ return 0;
+}
+
static inline void mutex_destroy(struct mutex *lock) {}
#endif
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);
--
2.25.1
