When same struct dst_entry can be used for many different neighbours we can not use it for pending confirmations. The datagram protocols can use MSG_CONFIRM to confirm the neighbour. When used with MSG_PROBE we do not reach the code where neighbour is confirmed, so we have to do the same slow lookup by using the dst_confirm_neigh() helper. When MSG_PROBE is not used, ip_append_data/ip6_append_data will set the skb flag dst_pending_confirm. Reported-by: YueHaibing <yuehaibing@huawei.com> Fixes: 5110effee8fd ("net: Do delayed neigh confirmation.") Fixes: f2bb4bedf35d ("ipv4: Cache output routes in fib_info nexthops.") Signed-off-by: Julian Anastasov <ja@ssi.bg> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>