Commit a93bf0ff authored Dec 18, 2017 by Xin Long Committed by David S. Miller Dec 19, 2017

vxlan: update skb dst pmtu on tx path



Unlike ip tunnels, now vxlan doesn't do any pmtu update for
upper dst pmtu, even if it doesn't match the lower dst pmtu
any more.

The problem can be reproduced when reducing the vxlan lower
dev's pmtu when running netperf. In jianlin's testing, the
performance went to 1/7 of the previous.

This patch is to update the upper dst pmtu to match the lower
dst pmtu on tx path so that packets can be sent out even when
lower dev's pmtu has been changed.

It also works for metadata dst.

Note that this patch doesn't process any pmtu icmp packet.
But even in the future, the support for pmtu icmp packets
process of udp tunnels will also needs this.

The same thing will be done for geneve in another patch.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 78aa0975

drivers/net/vxlan.c

+14 −0

Original line number	Diff line number	Diff line
		@@ -2155,6 +2155,13 @@ static void vxlan_xmit_one(struct sk_buff skb, struct net_device dev,
		}

		ndst = &rt->dst;
		if (skb_dst(skb)) {
		int mtu = dst_mtu(ndst) - VXLAN_HEADROOM;

		skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL,
		skb, mtu);
		}

		tos = ip_tunnel_ecn_encap(tos, old_iph, skb);
		ttl = ttl ? : ip4_dst_hoplimit(&rt->dst);
		err = vxlan_build_skb(skb, ndst, sizeof(struct iphdr),
		@@ -2190,6 +2197,13 @@ static void vxlan_xmit_one(struct sk_buff skb, struct net_device dev,
		goto out_unlock;
		}

		if (skb_dst(skb)) {
		int mtu = dst_mtu(ndst) - VXLAN6_HEADROOM;

		skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL,
		skb, mtu);
		}

		tos = ip_tunnel_ecn_encap(tos, old_iph, skb);
		ttl = ttl ? : ip6_dst_hoplimit(ndst);
		skb_scrub_packet(skb, xnet);

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