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From:   Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= <toke@redhat.com>
To:     Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc:     Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        Andrii Nakryiko <andriin@fb.com>,
        Doug Ledford <dledford@redhat.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <jakub.kicinski@netronome.com>,
        Jesper Dangaard Brouer <brouer@redhat.com>,
        John Fastabend <john.fastabend@gmail.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@redhat.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Shuah Khan <shuah@kernel.org>, netdev@vger.kernel.org,
        bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-rdma@vger.kernel.org, linux-kselftest@vger.kernel.org,
        clang-built-linux@googlegroups.com
Subject: Re: [PATCH bpf-next v2 00/10] tools: Use consistent libbpf include paths everywhere
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References: <157909756858.1192265.6657542187065456112.stgit@toke.dk> <20200115211900.h44pvhe57szzzymc@ast-mbp.dhcp.thefacebook.com>
Date:   Wed, 15 Jan 2020 23:09:44 +0100
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Alexei Starovoitov <alexei.starovoitov@gmail.com> writes:

> On Wed, Jan 15, 2020 at 03:12:48PM +0100, Toke H=C3=B8iland-J=C3=B8rgense=
n wrote:
>> The recent commit 6910d7d3867a ("selftests/bpf: Ensure bpf_helper_defs.h=
 are
>> taken from selftests dir") broke compilation against libbpf if it is ins=
talled
>> on the system, and $INCLUDEDIR/bpf is not in the include path.
>>=20
>> Since having the bpf/ subdir of $INCLUDEDIR in the include path has neve=
r been a
>> requirement for building against libbpf before, this needs to be fixed. =
One
>> option is to just revert the offending commit and figure out a different=
 way to
>> achieve what it aims for. However, this series takes a different approac=
h:
>> Changing all in-tree users of libbpf to consistently use a bpf/ prefix in
>> #include directives for header files from libbpf.
>
> I don't think such approach will work in all cases.
> Consider the user installing libbpf headers into /home/somebody/include/b=
pf/,
> passing that path to -I and trying to build bpf progs
> that do #include "bpf_helpers.h"...
> In the current shape of libbpf everything will compile fine,
> but after patch 8 of this series the compiler will not find bpf/bpf_helpe=
r_defs.h.
> So I think we have no choice, but to revert that part of Andrii's patch.
> Note that doing #include "" for additional library headers is a common pr=
actice.
> There was nothing wrong about #include "bpf_helper_defs.h" in bpf_helpers=
.h.

OK, I'll take another look at that bit and see if I can get it to work
with #include "bpf_helper_defs.h" and still function with the read-only
tree (and avoid stale headers).

-Toke