On Sat, Oct 13, 2018 at 6:54 AM Stefano Brivio <sbri...@redhat.com> wrote:
>
> We shouldn't abuse exceptions: if the destination MTU is already higher
> than what we're transmitting, no exception should be created.
makes sense, shouldn't ip(6) tunnels also do this?
>
> Fixes: 52a589d51f10 ("geneve: update skb dst pmtu on tx path")
> Fixes: a93bf0ff4490 ("vxlan: update skb dst pmtu on tx path")
> Signed-off-by: Stefano Brivio <sbri...@redhat.com>
> Reviewed-by: Sabrina Dubroca <s...@queasysnail.net>
> ---
> drivers/net/geneve.c | 7 +++----
> drivers/net/vxlan.c | 4 ++--
> include/net/dst.h | 10 ++++++++++
> 3 files changed, 15 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
> index 61c4bfbeb41c..493cd382b8aa 100644
> --- a/drivers/net/geneve.c
> +++ b/drivers/net/geneve.c
> @@ -830,8 +830,8 @@ static int geneve_xmit_skb(struct sk_buff *skb, struct
> net_device *dev,
> if (IS_ERR(rt))
> return PTR_ERR(rt);
>
> - skb_dst_update_pmtu(skb, dst_mtu(&rt->dst) -
> - GENEVE_IPV4_HLEN - info->options_len);
> + skb_tunnel_check_pmtu(skb, &rt->dst,
> + GENEVE_IPV4_HLEN + info->options_len);
>
> sport = udp_flow_src_port(geneve->net, skb, 1, USHRT_MAX, true);
> if (geneve->collect_md) {
> @@ -872,8 +872,7 @@ static int geneve6_xmit_skb(struct sk_buff *skb, struct
> net_device *dev,
> if (IS_ERR(dst))
> return PTR_ERR(dst);
>
> - skb_dst_update_pmtu(skb, dst_mtu(dst) -
> - GENEVE_IPV6_HLEN - info->options_len);
> + skb_tunnel_check_pmtu(skb, dst, GENEVE_IPV6_HLEN + info->options_len);
>
> sport = udp_flow_src_port(geneve->net, skb, 1, USHRT_MAX, true);
> if (geneve->collect_md) {
> diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
> index 22e0ce592e07..27bd586b94b0 100644
> --- a/drivers/net/vxlan.c
> +++ b/drivers/net/vxlan.c
> @@ -2194,7 +2194,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct
> net_device *dev,
> }
>
> ndst = &rt->dst;
> - skb_dst_update_pmtu(skb, dst_mtu(ndst) - VXLAN_HEADROOM);
> + skb_tunnel_check_pmtu(skb, ndst, VXLAN_HEADROOM);
>
> tos = ip_tunnel_ecn_encap(tos, old_iph, skb);
> ttl = ttl ? : ip4_dst_hoplimit(&rt->dst);
> @@ -2231,7 +2231,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct
> net_device *dev,
> goto out_unlock;
> }
>
> - skb_dst_update_pmtu(skb, dst_mtu(ndst) - VXLAN6_HEADROOM);
> + skb_tunnel_check_pmtu(skb, ndst, VXLAN6_HEADROOM);
>
> tos = ip_tunnel_ecn_encap(tos, old_iph, skb);
> ttl = ttl ? : ip6_dst_hoplimit(ndst);
> diff --git a/include/net/dst.h b/include/net/dst.h
> index 7f735e76ca73..6cf0870414c7 100644
> --- a/include/net/dst.h
> +++ b/include/net/dst.h
> @@ -527,4 +527,14 @@ static inline void skb_dst_update_pmtu(struct sk_buff
> *skb, u32 mtu)
> dst->ops->update_pmtu(dst, NULL, skb, mtu);
> }
>
> +static inline void skb_tunnel_check_pmtu(struct sk_buff *skb,
> + struct dst_entry *encap_dst,
> + int headroom)
> +{
> + u32 encap_mtu = dst_mtu(encap_dst);
> +
> + if (skb->len > encap_mtu - headroom)
> + skb_dst_update_pmtu(skb, encap_mtu - headroom);
> +}
> +
> #endif /* _NET_DST_H */
> --
> 2.19.1
>
