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From:   Eric Dumazet <edumazet@google.com>
Date:   Fri, 2 Jun 2023 14:43:06 +0200
Message-ID: <CANn89iKrpE7TVb8pTC+pWFDPJ2xcL3s9BhFB6DPxjK34he5RwQ@mail.gmail.com>
Subject: Re: [PATCH net-next] ipv6: lower "link become ready"'s level message
To:     Matthieu Baerts <matthieu.baerts@tessares.net>
Cc:     mptcp@lists.linux.dev, "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        David Ahern <dsahern@kernel.org>,
        Mat Martineau <martineau@kernel.org>,
        Stephen Hemminger <stephen@networkplumber.org>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
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On Fri, Jun 2, 2023 at 11:36=E2=80=AFAM Matthieu Baerts
<matthieu.baerts@tessares.net> wrote:
>
> This following message is printed in the console each time a network
> device configured with an IPv6 addresses is ready to be used:
>
>   ADDRCONF(NETDEV_CHANGE): <iface>: link becomes ready
>
> When netns are being extensively used -- e.g. by re-creating netns' with
> veth to discuss with each others for testing purposes like mptcp_join.sh
> selftest does -- it generates a lot of messages like that: more than 700
> when executing mptcp_join.sh with the latest version.
>
> It looks like this message is not that helpful after all: maybe it can
> be used as a sign to know if there is something wrong, e.g. if a device
> is being regularly reconfigured by accident? But even then, there are
> better ways to monitor and diagnose such issues.
>
> When looking at commit 3c21edbd1137 ("[IPV6]: Defer IPv6 device
> initialization until the link becomes ready.") which introduces this new
> message, it seems it had been added to verify that the new feature was
> working as expected. It could have then used a lower level than "info"
> from the beginning but it was fine like that back then: 17 years ago.
>
> It seems then OK today to simply lower its level, similar to commit
> 7c62b8dd5ca8 ("net/ipv6: lower the level of "link is not ready" messages"=
)
> and as suggested by Mat [1], Stephen and David [2].
>
> Link: https://lore.kernel.org/mptcp/614e76ac-184e-c553-af72-084f792e60b0@=
kernel.org/T/ [1]
> Link: https://lore.kernel.org/netdev/68035bad-b53e-91cb-0e4a-007f27d62b05=
@tessares.net/T/ [2]
> Suggested-by: Mat Martineau <martineau@kernel.org>
> Suggested-by: Stephen Hemminger <stephen@networkplumber.org>
> Suggested-by: David Ahern <dsahern@kernel.org>
> Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
> ---

Reviewed-by: Eric Dumazet <edumazet@google.com>