[PATCH 4.19 102/114] vti: do not confirm neighbor when do pmtu update

Greg Kroah-Hartman
2020-01-02T22:52:26Z

From: Hangbin Liu <liuhangbin@gmail.com>

[ Upstream commit 8247a79efa2f28b44329f363272550c1738377de ]

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
here.

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 <gnault@redhat.com>
Acked-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv4/ip_vti.c | 2 +-
net/ipv6/ip6_vti.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

--- a/net/ipv4/ip_vti.c
+++ b/net/ipv4/ip_vti.c
@@ -235,7 +235,7 @@ static netdev_tx_t vti_xmit(struct sk_bu

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)) {
icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
htonl(mtu));
--- a/net/ipv6/ip6_vti.c
+++ b/net/ipv6/ip6_vti.c
@@ -483,7 +483,7 @@ vti6_xmit(struct sk_buff *skb, struct ne

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)