media: v4l2-ctrls: Return the handler's error in v4l2_ctrl_handler_free()

v4l2_ctrl_handler_free() used to return void but changing this to int,
returning the handler's error code, enables the drivers to simply return
the handler's error in this common error handling pattern:

if (handler->error)
return v4l2_ctrl_handler_free(handler);

Suggested-by: Laurent Pinchart <[e-mail]>
Signed-off-by: Sakari Ailus <[e-mail]>
Reviewed-by: Laurent Pinchart <[e-mail]>
Reviewed-by: Hans Verkuil <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>

drivers/media/v4l2-core/v4l2-ctrls-core.c

···
 EXPORT_SYMBOL(v4l2_ctrl_handler_init_class);
 
 /* Free all controls and control refs */
-void v4l2_ctrl_handler_free(struct v4l2_ctrl_handler *hdl)
+int v4l2_ctrl_handler_free(struct v4l2_ctrl_handler *hdl)
 {
 	struct v4l2_ctrl_ref *ref, *next_ref;
 	struct v4l2_ctrl *ctrl, *next_ctrl;
 	struct v4l2_subscribed_event *sev, *next_sev;
 
-	if (hdl == NULL || hdl->buckets == NULL)
-		return;
+	if (!hdl)
+		return 0;
+
+	if (!hdl->buckets)
+		return hdl->error;
 
 	v4l2_ctrl_handler_free_request(hdl);
 
···
 	hdl->cached = NULL;
 	mutex_unlock(hdl->lock);
 	mutex_destroy(&hdl->_lock);
+
+	return hdl->error;
 }
 EXPORT_SYMBOL(v4l2_ctrl_handler_free);
 

include/media/v4l2-ctrls.h

···
  * @hdl:	The control handler.
  *
  * Does nothing if @hdl == NULL.
+ *
+ * Return: @hdl's error field or 0 if @hdl is NULL.
  */
-void v4l2_ctrl_handler_free(struct v4l2_ctrl_handler *hdl);
+int v4l2_ctrl_handler_free(struct v4l2_ctrl_handler *hdl);
 
 /**
  * v4l2_ctrl_lock() - Helper function to lock the handler