static int rtnl_dellink(struct sk_buff *skb, struct nlmsghdr *nlh,
			struct netlink_ext_ack *extack)
{
	struct net *net = sock_net(skb->sk);
	struct net_device *dev;
	struct ifinfomsg *ifm;
	char ifname[IFNAMSIZ];
	struct nlattr *tb[IFLA_MAX+1];
	int err;

	err = nlmsg_parse(nlh, sizeof(*ifm), tb, IFLA_MAX, ifla_policy, extack);
	if (err < 0)
		return err;

	if (tb[IFLA_IF_NETNSID])
		return -EOPNOTSUPP;

	if (tb[IFLA_IFNAME])
		nla_strlcpy(ifname, tb[IFLA_IFNAME], IFNAMSIZ);

	ifm = nlmsg_data(nlh);
	if (ifm->ifi_index > 0)
		dev = __dev_get_by_index(net, ifm->ifi_index);
	else if (tb[IFLA_IFNAME])
		dev = __dev_get_by_name(net, ifname);
	else if (tb[IFLA_GROUP])
		return rtnl_group_dellink(net, nla_get_u32(tb[IFLA_GROUP]));
	else
		return -EINVAL;

	if (!dev)
		return -ENODEV;

	return rtnl_delete_link(dev);
}
static int rtnl_dellink(struct sk_buff *skb, struct nlmsghdr *nlh,
			struct netlink_ext_ack *extack)
{
	struct net *net = sock_net(skb->sk);
	struct net_device *dev;
	struct ifinfomsg *ifm;
	char ifname[IFNAMSIZ];
	struct nlattr *tb[IFLA_MAX+1];
	int err;

	err = nlmsg_parse(nlh, sizeof(*ifm), tb, IFLA_MAX, ifla_policy, extack);
	if (err < 0)
		return err;

	if (tb[IFLA_IF_NETNSID])
		return -EOPNOTSUPP;

	if (tb[IFLA_IFNAME])
		nla_strlcpy(ifname, tb[IFLA_IFNAME], IFNAMSIZ);

	ifm = nlmsg_data(nlh);
	if (ifm->ifi_index > 0)
		dev = __dev_get_by_index(net, ifm->ifi_index);
	else if (tb[IFLA_IFNAME])
		dev = __dev_get_by_name(net, ifname);
	else if (tb[IFLA_GROUP])
		return rtnl_group_dellink(net, nla_get_u32(tb[IFLA_GROUP]));
	else
		return -EINVAL;

	if (!dev)
		return -ENODEV;

	return rtnl_delete_link(dev);
}