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From: Guillaume Nault <gnault@redhat.com>
To: Hangbin Liu <liuhangbin@gmail.com>
Cc: netdev@vger.kernel.org, Julian Anastasov <ja@ssi.bg>,
	Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>,
	David Ahern <dsahern@gmail.com>,
	Eric Dumazet <edumazet@google.com>,
	David Miller <davem@davemloft.net>,
	Pablo Neira <pablo@netfilter.org>,
	Stephen Hemminger <stephen@networkplumber.org>,
	Alexey Kodanev <alexey.kodanev@oracle.com>
Subject: Re: [PATCH net-next 0/8] disable neigh update for tunnels during pmtu update
Date: Thu, 19 Dec 2019 18:53:53 +0100	[thread overview]
Message-ID: <20191219175353.GC14566@linux.home> (raw)
In-Reply-To: <20191218115313.19352-1-liuhangbin@gmail.com>

On Wed, Dec 18, 2019 at 07:53:05PM +0800, Hangbin Liu wrote:
> When we setup a pair of gretap, ping each other and create neighbour cache.
> Then delete and recreate one side. We will never be able to ping6 to the new
> created gretap.
> 
> The reason is when we ping6 remote via gretap, we will call like
> 
> gre_tap_xmit()
>  - ip_tunnel_xmit()
>    - tnl_update_pmtu()
>      - skb_dst_update_pmtu()
>        - ip6_rt_update_pmtu()
>          - __ip6_rt_update_pmtu()
>            - dst_confirm_neigh()
>              - ip6_confirm_neigh()
>                - __ipv6_confirm_neigh()
>                  - n->confirmed = now
> 
> As the confirmed time updated, in neigh_timer_handler() the check for
> NUD_DELAY confirm time will pass and the neigh state will back to
> NUD_REACHABLE. So the old/wrong mac address will be used again.
> 
> If we do not update the confirmed time, the neigh state will go to
> neigh->nud_state = NUD_PROBE; then go to NUD_FAILED and re-create the
> neigh later, which is what IPv4 does.
> 
> We couldn't remove the ip6_confirm_neigh() directly as we still need it
> for TCP flows. To fix it, we have to pass a bool parameter to
> dst_ops.update_pmtu() and only disable neighbor update for tunnels.
> 

Apart from the missing Fixes tags, code looks good to me.

Reviewed-by: Guillaume Nault <gnault@redhat.com>


  parent reply	other threads:[~2019-12-19 17:54 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-22  6:19 [PATCH net] ipv6/route: only update neigh confirm time if pmtu changed Hangbin Liu
2019-11-22 18:04 ` David Miller
2019-11-26  9:17   ` Hangbin Liu
2019-12-03  2:11 ` [PATCHv2 net] ipv6/route: should not update neigh confirm time during PMTU update Hangbin Liu
2019-12-03  2:47   ` David Miller
2019-12-03 10:15     ` Hangbin Liu
2019-12-03 10:25       ` Hangbin Liu
2019-12-03 19:58         ` David Miller
2019-12-10  3:36           ` Hangbin Liu
2019-12-10 17:00             ` Guillaume Nault
2019-12-18 11:53   ` [PATCH net-next 0/8] disable neigh update for tunnels during pmtu update Hangbin Liu
2019-12-18 11:53     ` [PATCH net-next 1/8] net: add bool confirm_neigh parameter for dst_ops.update_pmtu Hangbin Liu
2019-12-18 11:53     ` [PATCH net-next 2/8] ip6_gre: do not confirm neighbor when do pmtu update Hangbin Liu
2019-12-18 11:53     ` [PATCH net-next 3/8] gtp: " Hangbin Liu
2019-12-18 11:53     ` [PATCH net-next 4/8] net/dst: add new function skb_dst_update_pmtu_no_confirm Hangbin Liu
2019-12-18 11:53     ` [PATCH net-next 5/8] tunnel: do not confirm neighbor when do pmtu update Hangbin Liu
2019-12-19 17:47       ` Guillaume Nault
2019-12-20  2:36         ` Hangbin Liu
2019-12-18 11:53     ` [PATCH net-next 6/8] vti: " Hangbin Liu
2019-12-18 11:53     ` [PATCH net-next 7/8] sit: " Hangbin Liu
2019-12-18 11:53     ` [PATCH net-next 8/8] net/dst: do not confirm neighbor for vxlan and geneve " Hangbin Liu
2019-12-19 17:49       ` Guillaume Nault
2019-12-18 12:01     ` [PATCH net-next 0/8] disable neigh update for tunnels during " Hangbin Liu
2019-12-19 17:57       ` Guillaume Nault
2019-12-20  2:48         ` Hangbin Liu
2019-12-19 17:53     ` Guillaume Nault [this message]
2019-12-20  3:25     ` [PATCHv4 net " Hangbin Liu
2019-12-20  3:25       ` [PATCHv4 net 1/8] net: add bool confirm_neigh parameter for dst_ops.update_pmtu Hangbin Liu
2019-12-20  3:25       ` [PATCHv4 net 2/8] ip6_gre: do not confirm neighbor when do pmtu update Hangbin Liu
2019-12-20  3:25       ` [PATCHv4 net 3/8] gtp: " Hangbin Liu
2019-12-21 18:35         ` Guillaume Nault
2019-12-20  3:25       ` [PATCHv4 net 4/8] net/dst: add new function skb_dst_update_pmtu_no_confirm Hangbin Liu
2019-12-20  3:25       ` [PATCHv4 net 5/8] tunnel: do not confirm neighbor when do pmtu update Hangbin Liu
2019-12-21 18:43         ` Guillaume Nault
2019-12-20  3:25       ` [PATCHv4 net 6/8] vti: " Hangbin Liu
2019-12-21 18:30         ` Guillaume Nault
2019-12-20  3:25       ` [PATCHv4 net 7/8] sit: " Hangbin Liu
2019-12-20  3:25       ` [PATCHv4 net 8/8] net/dst: do not confirm neighbor for vxlan and geneve " Hangbin Liu
2019-12-21 18:38         ` Guillaume Nault
2019-12-20 16:14       ` [PATCHv4 net 0/8] disable neigh update for tunnels during " David Ahern
2019-12-22  2:51       ` [PATCHv5 " Hangbin Liu
2019-12-22  2:51         ` [PATCHv5 net 1/8] net: add bool confirm_neigh parameter for dst_ops.update_pmtu Hangbin Liu
2019-12-22  2:51         ` [PATCHv5 net 2/8] ip6_gre: do not confirm neighbor when do pmtu update Hangbin Liu
2019-12-22  2:51         ` [PATCHv5 net 3/8] gtp: " Hangbin Liu
2019-12-22  2:51         ` [PATCHv5 net 4/8] net/dst: add new function skb_dst_update_pmtu_no_confirm Hangbin Liu
2019-12-22  2:51         ` [PATCHv5 net 5/8] tunnel: do not confirm neighbor when do pmtu update Hangbin Liu
2019-12-22  2:51         ` [PATCHv5 net 6/8] vti: " Hangbin Liu
2019-12-22  2:51         ` [PATCHv5 net 7/8] sit: " Hangbin Liu
2019-12-22  2:51         ` [PATCHv5 net 8/8] net/dst: do not confirm neighbor for vxlan and geneve " Hangbin Liu
2019-12-22 22:10         ` [PATCHv5 net 0/8] disable neigh update for tunnels during " Guillaume Nault
2019-12-25  6:30         ` David Miller

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