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From:   Alexei Starovoitov <alexei.starovoitov@gmail.com>
Date:   Mon, 9 Nov 2020 16:15:42 -0800
Message-ID: <CAADnVQLdXRFv1MYQu8k9QrECQxe3LFAfuyU244-9LfRT5snoqA@mail.gmail.com>
Subject: Re: [PATCH 02/24] bpf: Add build_id_parse_size function
To:     Jiri Olsa <jolsa@kernel.org>
Cc:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Song Liu <songliubraving@fb.com>,
        lkml <linux-kernel@vger.kernel.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Ingo Molnar <mingo@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Michael Petlan <mpetlan@redhat.com>,
        Ian Rogers <irogers@google.com>,
        Stephane Eranian <eranian@google.com>,
        Alexey Budankov <alexey.budankov@linux.intel.com>,
        Andi Kleen <ak@linux.intel.com>,
        Adrian Hunter <adrian.hunter@intel.com>
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On Mon, Nov 9, 2020 at 1:54 PM Jiri Olsa <jolsa@kernel.org> wrote:
>
> It's possible to have other build id types (other than default
> SHA1). Currently there's also ld support for MD5 build id.
>
> Adding build_id_parse_size function, that returns also size of
> the parsed build id, so we can recognize the build id type.
>
> Cc: Alexei Starovoitov <ast@kernel.org>
> Cc: Song Liu <songliubraving@fb.com>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
>  include/linux/buildid.h |  2 ++
>  lib/buildid.c           | 31 ++++++++++++++++++++++++-------
>  2 files changed, 26 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/buildid.h b/include/linux/buildid.h
> index 3be5b49719f1..edba89834b4c 100644
> --- a/include/linux/buildid.h
> +++ b/include/linux/buildid.h
> @@ -7,5 +7,7 @@
>  #define BUILD_ID_SIZE 20
>
>  int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id);
> +int build_id_parse_size(struct vm_area_struct *vma, unsigned char *build_id,
> +                       __u32 *size);

I think it's too many choices for such trivial api.
Just keep one build_id_parse() with two outputs
and fix the callers.