netdev - Re: [PATCH net] ipv6: Reflect MTU changes on PMTU of exceptions for MTU-less routes

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Date:   Sat, 3 Mar 2018 12:22:36 +0100
From:   Stefano Brivio <sbrivio@...hat.com>
To:     David Ahern <dsahern@...il.com>
Cc:     "David S . Miller" <davem@...emloft.net>,
        Wei Wang <weiwan@...gle.com>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Maciej Żenczykowski 
        <maze@...gle.com>, netdev@...r.kernel.org
Subject: Re: [PATCH net] ipv6: Reflect MTU changes on PMTU of exceptions for
 MTU-less routes

On Fri, 2 Mar 2018 15:39:03 -0700
David Ahern <dsahern@...il.com> wrote:

> On 3/2/18 8:36 AM, Stefano Brivio wrote:
> > Currently, administrative MTU changes on a given netdevice are
> > not reflected on route exceptions for MTU-less routes, with a
> > set PMTU value, for that device:
> > 
> >  # ip -6 route get 3000::b
> >  3000::b from :: dev vti_a proto kernel src 3000::a metric 256 pref medium
> >  # ping6 -c 1 -q -s10000 3000::b > /dev/null
> >  # ip netns exec a ip -6 route get 3000::b
> >  3000::b from :: dev vti_a src 3000::a metric 0
> >      cache expires 571sec mtu 4926 pref medium
> >  # ip link set dev vti_a mtu 3000
> >  # ip -6 route get 3000::b
> >  3000::b from :: dev vti_a src 3000::a metric 0
> >      cache expires 571sec mtu 4926 pref medium
> >  # ip link set dev vti_a mtu 9000
> >  # ip -6 route get 3000::b
> >  3000::b from :: dev vti_a src 3000::a metric 0
> >      cache expires 571sec mtu 4926 pref medium  
> 
> Addresses in the 2001:db8: range should be used for commit messages.

Thanks for pointing this out. I never related the "documentation
purposes" from RFC3849 to commit messages so far, but in the end this
is nothing else than documentation. I will post a v2 with updated
commit message.

> And please codify the above expectation as a test under
> tools/testing/selftests/net

And this, along with v2.

-- 
Stefano