linux-kernel - Re: [PATCH bpf-next v5 00/11] tools: Use consistent libbpf include paths everywhere

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Message-ID: <874kwpndc5.fsf@toke.dk>
Date:   Tue, 21 Jan 2020 14:33:46 +0100
From:   Toke Høiland-Jørgensen <toke@...hat.com>
To:     Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andriin@...com>,
        Doug Ledford <dledford@...hat.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        John Fastabend <john.fastabend@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Shuah Khan <shuah@...nel.org>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        linux-rdma@...r.kernel.org,
        "open list\:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@...r.kernel.org>,
        clang-built-linux@...glegroups.com
Subject: Re: [PATCH bpf-next v5 00/11] tools: Use consistent libbpf include paths everywhere

Andrii Nakryiko <andrii.nakryiko@...il.com> writes:

> On Mon, Jan 20, 2020 at 5:08 AM Toke Høiland-Jørgensen <toke@...hat.com> wrote:
>>
>> We are currently being somewhat inconsistent with the libbpf include paths,
>> which makes it difficult to move files from the kernel into an external
>> libbpf-using project without adjusting include paths.
>>
>> Having the bpf/ subdir of $INCLUDEDIR in the include path has never been a
>> requirement for building against libbpf before, and indeed the libbpf pkg-config
>> file doesn't include it. So let's make all libbpf includes across the kernel
>> tree use the bpf/ prefix in their includes. Since bpftool skeleton generation
>> emits code with a libbpf include, this also ensures that those can be used in
>> existing external projects using the regular pkg-config include path.
>>
>> This turns out to be a somewhat invasive change in the number of files touched;
>> however, the actual changes to files are fairly trivial (most of them are simply
>> made with 'sed'). The series is split to make the change for one tool subdir at
>> a time, while trying not to break the build along the way. It is structured like
>> this:
>>
>> - Patch 1-3: Trivial fixes to Makefiles for issues I discovered while changing
>>   the include paths.
>>
>> - Patch 4-8: Change the include directives to use the bpf/ prefix, and updates
>>   Makefiles to make sure tools/lib/ is part of the include path, but without
>>   removing tools/lib/bpf
>>
>> - Patch 9-11: Remove tools/lib/bpf from include paths to make sure we don't
>>   inadvertently re-introduce includes without the bpf/ prefix.
>>
>> Changelog:
>>
>> v5:
>>   - Combine the libbpf build rules in selftests Makefile (using Andrii's
>>     suggestion for a make rule).
>>   - Re-use self-tests libbpf build for runqslower (new patch 10)
>>   - Formatting fixes
>>
>> v4:
>>   - Move runqslower error on missing BTF into make rule
>>   - Make sure we don't always force a rebuild selftests
>>   - Rebase on latest bpf-next (dropping patch 11)
>>
>> v3:
>>   - Don't add the kernel build dir to the runqslower Makefile, pass it in from
>>     selftests instead.
>>   - Use libbpf's 'make install_headers' in selftests instead of trying to
>>     generate bpf_helper_defs.h in-place (to also work on read-only filesystems).
>>   - Use a scratch builddir for both libbpf and bpftool when building in selftests.
>>   - Revert bpf_helpers.h to quoted include instead of angled include with a bpf/
>>     prefix.
>>   - Fix a few style nits from Andrii
>>
>> v2:
>>   - Do a full cleanup of libbpf includes instead of just changing the
>>     bpf_helper_defs.h include.
>>
>> ---
>>
>
> Looks good, it's a clear improvement on what we had before, thanks!
>
> It doesn't re-build bpftool when bpftool sources changes, but I think
> it was like that even before, so no need to block on that. Would be
> nice to have a follow up fixing that, though. $(wildcard
> $(BPFTOOL_DIR)/*.[ch] $(BPFTOOL_DIR)/Makefile) should do it, same as
> for libbpf.

Yeah, I did realise there was some potential for improvement for bpftool
as well, but I got enough of Makefiles for now :)

I'll see if I can't circle back to this at some point...

> So, for the series:
>
> Acked-by: Andrii Nakryiko <andriin@...com>
> Tested-by: Andrii Nakryiko <andriin@...com>

Thanks!

-Toke