Le 12/03/2024 à 02:10, Waiman Long a écrit :

On 3/11/24 19:47, George Stark wrote:

quoted

Hello Waiman, Marek

Thanks for the review.

I've never used lockdep for debug but it seems preferable to
keep that feature working. It could be look like this:

diff --git a/include/linux/mutex.h b/include/linux/mutex.h
index f7611c092db7..574f6de6084d 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 +117,31 @@ do {                            \

 #ifdef CONFIG_DEBUG_MUTEXES

+int debug_devm_mutex_init(struct device *dev, struct mutex *lock);
+
+#define devm_mutex_init(dev, mutex)            \
+({                            \
+    int ret;                    \
+    mutex_init(mutex);                \
+    ret = debug_devm_mutex_init(dev, mutex);    \
+    ret;                        \
+})

The int ret variable is not needed. The macro can just end with 
debug_devm_mutex_init().

quoted

+
 void mutex_destroy(struct mutex *lock);

 #else

+/*
+* When CONFIG_DEBUG_MUTEXES is off mutex_destroy is just a nop so
+* there's no really need to register it in devm subsystem.

"no really need"?

quoted

+*/
+#define devm_mutex_init(dev, mutex)            \
+({                            \
+    typecheck(struct device *, dev);        \
+    mutex_init(mutex);                \
+    0;                        \
+})

Do we need a typecheck() here? Compilation will fail with 
CONFIG_DEBUG_MUTEXES if dev is not a device pointer.

I guess the idea is to have it fail _also_ when CONFIG_DEBUG_MUTEXES is 
not selected, in order to discover errors as soon as possible.

quoted

+
 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..967a5367c79a 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 debug_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