void udp_sk_rx_dst_set(struct sock *sk, struct dst_entry *dst)
{
	struct dst_entry *old;

	if (dst_hold_safe(dst)) {
		old = xchg(&sk->sk_rx_dst, dst);
		dst_release(old);
	}
}
void udp_sk_rx_dst_set(struct sock *sk, struct dst_entry *dst)
{
	struct dst_entry *old;

	if (dst_hold_safe(dst)) {
		old = xchg(&sk->sk_rx_dst, dst);
		dst_release(old);
	}
}