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From:   Alexei Starovoitov <alexei.starovoitov@gmail.com>
Date:   Tue, 21 Jun 2022 11:44:17 -0700
Message-ID: <CAADnVQJKiiFafS5R3-3RmKCRNxWzLuqhqyahRN=eyM4dsg07-A@mail.gmail.com>
Subject: Re: [PATCH bpf-next 4/7] libbpf: Add type match support
To:     =?UTF-8?Q?Daniel_M=C3=BCller?= <deso@posteo.net>
Cc:     bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
        Andrii Nakryiko <andrii@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Kernel Team <kernel-team@fb.com>
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On Tue, Jun 21, 2022 at 9:46 AM Daniel M=C3=BCller <deso@posteo.net> wrote:
>
> On Mon, Jun 20, 2022 at 04:59:19PM -0700, Alexei Starovoitov wrote:
> > On Mon, Jun 20, 2022 at 11:17:10PM +0000, Daniel M=C3=BCller wrote:
> > > +int bpf_core_types_match(const struct btf *local_btf, __u32 local_id=
,
> > > +                    const struct btf *targ_btf, __u32 targ_id)
> > > +{
> >
> > The libbpf and kernel support for types_match looks nearly identical.
> > Maybe put in tools/lib/bpf/relo_core.c so it's one copy for both?
>
> Thanks for the suggestion. Yes, at least for parts we should probably do =
it.
>
> Would you happen to know why that has not been done for
> bpf_core_types_are_compat equally? Is it because of the recursion level
> tracking that is only present in the kernel? I'd think that similar reaso=
ning
> applies here.

Historical. Probably should be combined.
Code duplication is the source of all kinds of maintenance issues
and subtle bugs.