ip6_tunnel: do not use dst6_mtu() in ip4ip6_err() and ip6erspan_tunnel_xmit()

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.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260609091337.2672441-1-edumazet@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 365b4059eb20354c256c491a16db0e606e0a9790..48039f00b4bc4321c1502714a98dbf209a7ea398 100644 (file)
--- 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 (file)
--- 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);