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Date:   Thu, 16 Jan 2020 20:14:32 -0800
From:   Alexei Starovoitov <alexei.starovoitov@gmail.com>
To:     Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= <toke@redhat.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 <kuba@kernel.org>,
        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 v3 00/11] tools: Use consistent libbpf include
 paths everywhere
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On Thu, Jan 16, 2020 at 02:22:11PM +0100, Toke H?iland-J?rgensen wrote:
> The recent commit 6910d7d3867a ("selftests/bpf: Ensure bpf_helper_defs.h are
> taken from selftests dir") broke compilation against libbpf if it is installed
> on the system, and $INCLUDEDIR/bpf is not in the include path.
> 
> Since having the bpf/ subdir of $INCLUDEDIR in the include path has never 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. 

The offending commit has been in the tree for a week. So I applied Andrii's
revert of that change. It reintroduced the build dependency issue, but we lived
with it for long time, so we can take time to fix it cleanly.
I suggest to focus on that build dependency first.

> However, this series takes a different approach:
> Changing all in-tree users of libbpf to consistently use a bpf/ prefix in
> #include directives for header files from libbpf.

I'm not sure it's a good idea. It feels nice, but think of a message we're
sending to everyone. We will get spamed with question: does bpf community
require all libbpf users to use bpf/ prefix ? What should be our answer?
Require or recommend? If require.. what for? It works as-is. If recommend then
why suddenly we're changing all files in selftests and samples?
There is no good answer here. I think we should leave the things as-is.
And fix build dep differently.

Patches 1-3 are still worth doing.