Hello Christophe

On 12/14/23 13:06, Christophe Leroy wrote:

...

So you abandonned the idea of using mutex.h ?

I'm not the one who make a choice here. The patch [1] you're talking 
about was seen by everyone but it seems like no one had shown interest.
For me personally approach with #define mutex_destroy is not very usual
but if even slight mixing device with mutex.h is unacceptable what else
can we do? Avoiding the need to allocate devm slot for empty 
mutex_destroy is more important.

Should I make series #4 with the patch [1] to give it a last chance?

[1] 
https://lore.kernel.org/lkml/377e4437-7051-4d88-ae68-1460bcd692e1@redhat.com/T/#m3f6df30ffccaccb1df4669a327f349164f572931 (local)

I can't see the point to spread mutex functions into devm-helpers.h

Adding a mutex_destroy macro for this purpose looks odd. And if someone
defines a new version of mutex_destroy() and forget the macro, it will
go undetected.

Usually macros of that type serve the purpose of defining a fallback
when the macro is not defined. In that case, when someone adds a new
version without defining the macro, it gets detected because if
conflicts with the fallback.
But in your case it works the other way round, so I will just go undetected.

For me the best solution remains to use mutex.h and have
devm_mutex_init() defined or declared at the same place as mutex_destroy().

quoted

Signed-off-by: George Stark <redacted>
---
   include/linux/devm-helpers.h | 27 +++++++++++++++++++++++++++
   1 file changed, 27 insertions(+)

diff --git a/include/linux/devm-helpers.h b/include/linux/devm-helpers.h
index 74891802200d..4043c3481d2e 100644
--- a/include/linux/devm-helpers.h
+++ b/include/linux/devm-helpers.h

@@ -24,6 +24,7 @@
    */

   #include <linux/device.h>
+#include <linux/mutex.h>
   #include <linux/workqueue.h>

   static inline void devm_delayed_work_drop(void *res)

@@ -76,4 +77,30 @@ static inline int devm_work_autocancel(struct device *dev,
          return devm_add_action(dev, devm_work_drop, w);
   }

+#ifdef mutex_destroy
+static inline void devm_mutex_release(void *res)
+{
+       mutex_destroy(res);
+}
+#endif
+
+/**
+ * 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.
+ */
+static inline int devm_mutex_init(struct device *dev, struct mutex *lock)
+{
+       mutex_init(lock);
+#ifdef mutex_destroy
+       return devm_add_action_or_reset(dev, devm_mutex_release, lock);
+#else
+       return 0;
+#endif
+}
+
   #endif
--

2.25.1

-- 
Best regards
George