netdev - Re: [PATCH net-next 5/8] tunnel: do not confirm neighbor when do pmtu update

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Date:   Fri, 20 Dec 2019 10:36:41 +0800
From:   Hangbin Liu <liuhangbin@...il.com>
To:     Guillaume Nault <gnault@...hat.com>
Cc:     netdev@...r.kernel.org, Julian Anastasov <ja@....bg>,
        Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        David Ahern <dsahern@...il.com>,
        Eric Dumazet <edumazet@...gle.com>,
        David Miller <davem@...emloft.net>,
        Pablo Neira <pablo@...filter.org>,
        Stephen Hemminger <stephen@...workplumber.org>,
        Alexey Kodanev <alexey.kodanev@...cle.com>
Subject: Re: [PATCH net-next 5/8] tunnel: do not confirm neighbor when do
 pmtu update

Hi Guillaume,

Thanks a lot for your review.
On Thu, Dec 19, 2019 at 06:47:20PM +0100, Guillaume Nault wrote:
> On Wed, Dec 18, 2019 at 07:53:10PM +0800, Hangbin Liu wrote:
> > 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 ipv4 tunnel is not affected as __ip_rt_update_pmtu() does not call
> > dst_confirm_neigh(), we still not do neigh confirm to keep consistency with
> > IPv6 code.
> > 
> This is a bit confusing. IPv4 tunnels (e.g. gretap) are affected, as show
> by your reproducer. Quoting patch 0:

Ah, yes, I forgot that IPv6 over GRE4 also affects. I will update the
commit description.

> 
> Fixes: 0dec879f636f ("net: use dst_confirm_neigh for UDP, RAW, ICMP, L2TP")
> 
I will add it


Thanks
Hangbin