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Subject: Re: [PATCH bpf-next v3 2/7] net: export inet_lookup_reuseport and
 inet6_lookup_reuseport
To:     Lorenz Bauer <lmb@isovalent.com>,
        Kuniyuki Iwashima <kuniyu@amazon.com>
Cc:     andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org,
        davem@davemloft.net, dsahern@kernel.org, edumazet@google.com,
        haoluo@google.com, hemanthmalla@gmail.com, joe@wand.net.nz,
        john.fastabend@gmail.com, jolsa@kernel.org, kpsingh@kernel.org,
        kuba@kernel.org, linux-kernel@vger.kernel.org,
        linux-kselftest@vger.kernel.org, martin.lau@linux.dev,
        mykolal@fb.com, netdev@vger.kernel.org, pabeni@redhat.com,
        sdf@google.com, shuah@kernel.org, song@kernel.org,
        willemdebruijn.kernel@gmail.com, yhs@fb.com
References: <20230613-so-reuseport-v3-2-907b4cbb7b99@isovalent.com>
 <20230626173249.57682-1-kuniyu@amazon.com>
 <CAN+4W8hnPzhuKPorSjHeOQHFgAuk=A9oa1hW5jckUPoF=5zEQQ@mail.gmail.com>
From:   Daniel Borkmann <daniel@iogearbox.net>
Message-ID: <e21aa61a-803b-bb82-d56e-2db0c839477b@iogearbox.net>
Date:   Tue, 27 Jun 2023 12:19:41 +0200
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On 6/27/23 10:56 AM, Lorenz Bauer wrote:
> On Mon, Jun 26, 2023 at 6:33 PM Kuniyuki Iwashima <kuniyu@amazon.com> wrote:
>>
>> From: Lorenz Bauer <lmb@isovalent.com>
>> Date: Mon, 26 Jun 2023 16:08:59 +0100
>>> Rename the existing reuseport helpers for IPv4 and IPv6 so that they
>>> can be invoked in the follow up commit. Export them so that DCCP which
>>> may be built as a module can access them.
>>
>> We need not export the functions unless there is a real user.
>>
>> I added a deprecation notice for DCCP recently, so I bet DCCP
>> will not get SO_REUSEPORT support.
>> https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=b144fcaf46d4
> 
> Misleading commit message, it turns out that ipv6 as a module also
> needs (the v6 functions at least) to be EXPORT_SYMBOL'd. That's
> because of some special shenanigans where inet6_hashtables.c is linked
> into vmlinux even when CONFIG_IPV6=m.
> 
> Also not sure how to work around this: DCCP may be deprecated but
> without the export a module build of it fails.

If it breaks the build, then we need to export it.