netdev - Re: [PATCH bpf-next] bpf: add config to allow loading modules with BTF mismatches

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Date:   Wed, 23 Feb 2022 12:34:24 +0800
From:   Shung-Hsi Yu <shung-hsi.yu@...e.com>
To:     Connor O'Brien <connoro@...gle.com>
CC:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>, netdev@...r.kernel.org,
        bpf@...r.kernel.org, linux-kernel@...r.kernel.org,
        Michal Suchánek <msuchanek@...e.de>
Subject: Re: [PATCH bpf-next] bpf: add config to allow loading modules with
 BTF mismatches

On Wed, Feb 23, 2022 at 01:28:14AM +0000, Connor O'Brien wrote:
> BTF mismatch can occur for a separately-built module even when the ABI
> is otherwise compatible and nothing else would prevent successfully
> loading. Add a new config to control how mismatches are handled. By
> default, preserve the current behavior of refusing to load the
> module. If MODULE_ALLOW_BTF_MISMATCH is enabled, load the module but
> ignore its BTF information.
> 
> Suggested-by: Yonghong Song <yhs@...com>
> Suggested-by: Michal Suchánek <msuchanek@...e.de>
> Signed-off-by: Connor O'Brien <connoro@...gle.com>

Maybe reference the discussion thread as well?

Link: https://lore.kernel.org/bpf/CAADnVQJ+OVPnBz8z3vNu8gKXX42jCUqfuvhWAyCQDu8N_yqqwQ@mail.gmail.com/

Otherwise

Acked-by: Shung-Hsi Yu <shung-hsi.yu@...e.com>

> ---
> Hello,
> 
> In the discussion regarding BTF compatibility & modules, there seemed
> to be broad agreement that an option to ignore mismatches would be
> reasonable. Currently the only option for handling this problem seems
> to be to disable BTF entirely, so this would at least be an
> incremental improvement.
> 
> Thanks,
> Connor