This is a minor performance / conceptual fix. 1) ip6erspan_tunnel_xmit() ERSPAN tunnel can mirror both IPv4 and IPv6 traffic, skb (the packet being mirrored) can be an IPv4 packet, and thus dst can be an IPv4 destination entry Use dst_mtu() which contains generic logic for both families. 2) ip4ip6_err() skb2 has been prepared as an IPv4 packet, and its destination is an IPv4 route. dst6_mtu() is optimized for IPv6 destinations and uses INDIRECT_CALL_1 to call ip6_mtu() directly if the ops match. We should use dst4_mtu() instead. Fixes: b40f0130a23b ("ipv6: use dst6_mtu() instead of dst_mtu()") Signed-off-by: Eric Dumazet --- net/ipv6/ip6_gre.c | 2 +- net/ipv6/ip6_tunnel.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c index 365b4059eb20354c256c491a16db0e606e0a9790..48039f00b4bc4321c1502714a98dbf209a7ea398 100644 --- a/net/ipv6/ip6_gre.c +++ b/net/ipv6/ip6_gre.c @@ -1058,7 +1058,7 @@ static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff *skb, /* TooBig packet may have updated dst->dev's mtu */ if (!t->parms.collect_md && dst) { mtu = READ_ONCE(dst_dev(dst)->mtu); - if (dst6_mtu(dst) > mtu) + if (dst_mtu(dst) > mtu) dst->ops->update_pmtu(dst, NULL, skb, mtu, false); } err = ip6_tnl_xmit(skb, dev, dsfield, &fl6, encap_limit, &mtu, diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c index 9d1037ac082f6aad36c152ffdbe0f30237b65fc3..bf5cd5d4adcdfa86eb7a3c0a27db3cadb69499ae 100644 --- a/net/ipv6/ip6_tunnel.c +++ b/net/ipv6/ip6_tunnel.c @@ -650,7 +650,7 @@ ip4ip6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, /* change mtu on this route */ if (rel_type == ICMP_DEST_UNREACH && rel_code == ICMP_FRAG_NEEDED) { - if (rel_info > dst6_mtu(skb_dst(skb2))) + if (rel_info > dst4_mtu(skb_dst(skb2))) goto out; skb_dst_update_pmtu_no_confirm(skb2, rel_info); -- 2.54.0.1064.gd145956f57-goog