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From:   Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Date:   Tue, 17 Oct 2023 21:57:34 -0400
Message-ID: <CAF=yD-K7SbUkeVkTcZyR_x-+fgtpcBr0R6e75J=C_Af54J+zew@mail.gmail.com>
Subject: Re: [PATCH v2 net-next] ipv6: avoid atomic fragment on GSO packets
To:     Yan Zhai <yan@cloudflare.com>
Cc:     Florian Westphal <fw@strlen.de>, netdev@vger.kernel.org,
        "David S. Miller" <davem@davemloft.net>,
        David Ahern <dsahern@kernel.org>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, Aya Levin <ayal@nvidia.com>,
        Tariq Toukan <tariqt@nvidia.com>, linux-kernel@vger.kernel.org,
        kernel-team@cloudflare.com
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On Tue, Oct 17, 2023 at 9:42=E2=80=AFPM Yan Zhai <yan@cloudflare.com> wrote=
:
>
> On Tue, Oct 17, 2023 at 3:02=E2=80=AFPM Florian Westphal <fw@strlen.de> w=
rote:
> >
> > Yan Zhai <yan@cloudflare.com> wrote:
> > > Refactor __ip6_finish_output code to separate GSO and non-GSO packet
> > > processing. It mirrors __ip_finish_output logic now. Add an extra che=
ck
> > > in GSO handling to avoid atomic fragments. Lastly, drop dst_allfrag
> > > check, which is no longer true since commit 9d289715eb5c ("ipv6: stop
> > > sending PTB packets for MTU < 1280").
> >
> >
> > > -     if ((skb->len > mtu && !skb_is_gso(skb)) ||
> > > -         dst_allfrag(skb_dst(skb)) ||
> >
> > My preference is to first remove dst_allfrag, i.e. do this in
> > a separate change.
>
> You mean completely removing all dst_allfrag references and related
> stuff such like IP cork flags/socket flags? I was debating, it might
> be cleaner that way but it does not fit so well with the subject of
> this patch. I can open a new patchset to clean that up separately. For
> this one, I guess I can keep dst_allfrag for now and come back with a
> V3. Does that sound good to you?

The second paragraph in the commit message really makes
clear that this combines three changes in one patch. Of which
the largest one in terms of code churn is supposed to be a
NOOP.

Separating into three patches will make all three more clear.
They can be pushed as one series, conceivably.