Re: [PATCH net 2/2] geneve, vxlan: Don't set exceptions if skb->len < mtu
From: Xin Long <lucien.xin@gmail.com>
Date: 2018-10-15 13:45:29
On Sat, Oct 13, 2018 at 6:54 AM Stefano Brivio [off-list ref] 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?
quoted hunk ↗ jump to hunk
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 <redacted> Reviewed-by: Sabrina Dubroca <sd@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