Without keeping dst, the tunnel will not update any mtu/pmtu info, since it does not have a dst on the skb.
Reproducer: client(ipgre_tap1 - eth1) <-----> (eth1 - ipgre_tap1)server After reducing eth1's mtu on client, then perforamnce became 0. This patch is to netif_keep_dst in gre_tap_init, as ipgre does. Reported-by: Jianlin Shi <ji...@redhat.com> Signed-off-by: Xin Long <lucien....@gmail.com> --- net/ipv4/ip_gre.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c index 0162fb9..8b837f6 100644 --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -1223,6 +1223,7 @@ static int gre_tap_init(struct net_device *dev) { __gre_tunnel_init(dev); dev->priv_flags |= IFF_LIVE_ADDR_CHANGE; + netif_keep_dst(dev); return ip_tunnel_init(dev); } -- 2.1.0