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References: <20230413171918.GX17993@unreal> <20230414022736.63374-1-bobankhshen@gmail.com>
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From:   Eric Dumazet <edumazet@google.com>
Date:   Fri, 14 Apr 2023 16:17:40 +0200
Message-ID: <CANn89i+k9Qn_8bpJb+Cgh_b4VYYVNArSGG3LmR+d3sxjxdxxbw@mail.gmail.com>
Subject: Re: [PATCH net-next] lib/win_minmax: export symbol of minmax_running_min
To:     Yixin Shen <bobankhshen@gmail.com>
Cc:     leon@kernel.org, akpm@linux-foundation.org, davem@davemloft.net,
        linux-kernel@vger.kernel.org, ncardwell@google.com,
        netdev@vger.kernel.org, rdunlap@infradead.org
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On Fri, Apr 14, 2023 at 4:27=E2=80=AFAM Yixin Shen <bobankhshen@gmail.com> =
wrote:
>
> > Please provide in-tree kernel user for that EXPORT_SYMBOL.
>
> It is hard to provide such an in-tree kernel user. We are trying to
> implement newer congestion control algorithms as dynamically loaded modul=
es.
> For example, Copa(NSDI'18) which is adopted by Facebook needs to maintain
> such windowed min filters. Althought it is true that we can just
> copy-and-paste the code inside lib/win_minmax, it it more convenient to
> give the same status of minmax_running_min as minmax_running_max.
> It is confusing that only minmax_running_max is exported.

This is needed by net/ipv4/tcp_bbr.c , which can be a module.

> If this patch is rejected because the changes are too significant,

Well, this path would soon be reverted by people using bots/tools to
detect unused functions,
or unused EXPORT symbols.

So there is no point accepting it, before you submit the CC in the
official linux tree.