On Wed, 28 Jan 2026 13:25:37 +0200 Tariq Toukan wrote:

 static int __devlink_nl_pre_doit(struct sk_buff *skb, struct genl_info *info,
 				 u8 flags)
 {
+	bool parent_dev = flags & DEVLINK_NL_FLAG_OPTIONAL_PARENT_DEV;
 	bool dev_lock = flags & DEVLINK_NL_FLAG_NEED_DEV_LOCK;
+	struct devlink *devlink, *parent_devlink = NULL;
+	struct net *net = genl_info_net(info);
+	struct nlattr **attrs = info->attrs;
 	struct devlink_port *devlink_port;
-	struct devlink *devlink;
 	int err;
 
-	devlink = devlink_get_from_attrs_lock(genl_info_net(info), info->attrs,
-					      dev_lock);
-	if (IS_ERR(devlink))
-		return PTR_ERR(devlink);
+	if (parent_dev && attrs[DEVLINK_ATTR_PARENT_DEV]) {
+		parent_devlink = devlink_get_parent_from_attrs_lock(net, attrs);
+		if (IS_ERR(parent_devlink))
+			return PTR_ERR(parent_devlink);
+		info->user_ptr[1] = parent_devlink;

Let's convert devlink to use proper overlay struct over info->cb ?
The user_ptr array only has two entries so devlink stuffs all the
extra pointers into the second slot. But the cb is much larger - 48B
so we can easily give each of these values a dedicated pointer.

+		/* Drop the parent devlink lock but don't release the reference.
+		 * This will keep it alive until the end of the request.
+		 */

To be clear -- devlink instances do not behave like netdev instances.
netdev instances prevent unregistration of the netdev.
devlink refs are normal refs, they just keep the memory around.
If memory serves me..

+		devl_unlock(parent_devlink);
+	}
 
+	devlink = devlink_get_from_attrs_lock(net, attrs, dev_lock);
+	if (IS_ERR(devlink)) {
+		err = PTR_ERR(devlink);
+		goto parent_put;
+	}