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Date:   Sun, 22 Dec 2019 10:51:14 +0800
From:   Hangbin Liu <>
Cc:     Julian Anastasov <>,
        Marcelo Ricardo Leitner <>,
        David Ahern <>,
        Eric Dumazet <>,
        Guillaume Nault <>,
        David Miller <>,
        Pablo Neira <>,
        Stephen Hemminger <>,
        Alexey Kodanev <>,
        Hangbin Liu <>
Subject: [PATCHv5 net 6/8] vti: do not confirm neighbor when do pmtu update

When do IPv6 tunnel PMTU update and calls __ip6_rt_update_pmtu() in the end,
we should not call dst_confirm_neigh() as there is no two-way communication.

Although vti and vti6 are immune to this problem because they are IFF_NOARP
interfaces, as Guillaume pointed. There is still no sense to confirm neighbour

v5: Update commit description.
v4: No change.
v3: Do not remove dst_confirm_neigh, but add a new bool parameter in
    dst_ops.update_pmtu to control whether we should do neighbor confirm.
    Also split the big patch to small ones for each area.
v2: Remove dst_confirm_neigh in __ip6_rt_update_pmtu.

Reviewed-by: Guillaume Nault <>
Acked-by: David Ahern <>
Signed-off-by: Hangbin Liu <>
 net/ipv4/ip_vti.c  | 2 +-
 net/ipv6/ip6_vti.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/ip_vti.c b/net/ipv4/ip_vti.c
index cfb025606793..fb9f6d60c27c 100644
--- a/net/ipv4/ip_vti.c
+++ b/net/ipv4/ip_vti.c
@@ -214,7 +214,7 @@ static netdev_tx_t vti_xmit(struct sk_buff *skb, struct net_device *dev,
 	mtu = dst_mtu(dst);
 	if (skb->len > mtu) {
-		skb_dst_update_pmtu(skb, mtu);
+		skb_dst_update_pmtu_no_confirm(skb, mtu);
 		if (skb->protocol == htons(ETH_P_IP)) {
diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c
index 024db17386d2..6f08b760c2a7 100644
--- a/net/ipv6/ip6_vti.c
+++ b/net/ipv6/ip6_vti.c
@@ -479,7 +479,7 @@ vti6_xmit(struct sk_buff *skb, struct net_device *dev, struct flowi *fl)
 	mtu = dst_mtu(dst);
 	if (skb->len > mtu) {
-		skb_dst_update_pmtu(skb, mtu);
+		skb_dst_update_pmtu_no_confirm(skb, mtu);
 		if (skb->protocol == htons(ETH_P_IPV6)) {
 			if (mtu < IPV6_MIN_MTU)

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