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Subject: Re: [PATCH] tools include: Add __sum16 and __wsum definitions.
To:     Ian Rogers <irogers@google.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>,
        Song Liu <songliubraving@fb.com>, linux-kernel@vger.kernel.org,
        Alexei Starovoitov <ast@kernel.org>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <kafai@fb.com>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>,
        Tiezhu Yang <yangtiezhu@loongson.cn>, netdev@vger.kernel.org,
        bpf@vger.kernel.org
Cc:     Stephane Eranian <eranian@google.com>
References: <20210307223024.4081067-1-irogers@google.com>
From:   Daniel Borkmann <daniel@iogearbox.net>
Message-ID: <4aa2a66d-b8e4-adfe-8b61-615d98012a65@iogearbox.net>
Date:   Mon, 8 Mar 2021 14:37:32 +0100
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On 3/7/21 11:30 PM, Ian Rogers wrote:
> This adds definitions available in the uapi version.
> 
> Explanation:
> In the kernel include of types.h the uapi version is included.
> In tools the uapi/linux/types.h and linux/types.h are distinct.
> For BPF programs a definition of __wsum is needed by the generated
> bpf_helpers.h. The definition comes either from a generated vmlinux.h or
> from <linux/types.h> that may be transitively included from bpf.h. The
> perf build prefers linux/types.h over uapi/linux/types.h for
> <linux/types.h>*. To allow tools/perf/util/bpf_skel/bpf_prog_profiler.bpf.c
> to compile with the same include path used for perf then these
> definitions are necessary.
> 
> There is likely a wider conversation about exactly how types.h should be
> specified and the include order used by the perf build - it is somewhat
> confusing that tools/include/uapi/linux/bpf.h is using the non-uapi
> types.h.
> 
> *see tools/perf/Makefile.config:
> ...
> INC_FLAGS += -I$(srctree)/tools/include/
> INC_FLAGS += -I$(srctree)/tools/arch/$(SRCARCH)/include/uapi
> INC_FLAGS += -I$(srctree)/tools/include/uapi
> ...
> The include directories are scanned from left-to-right:
> https://gcc.gnu.org/onlinedocs/gcc/Directory-Options.html
> As tools/include/linux/types.h appears before
> tools/include/uapi/linux/types.h then I say it is preferred.
> 
> Signed-off-by: Ian Rogers <irogers@google.com>

Given more related to perf build infra, I presume Arnaldo would pick
this one up?

Thanks,
Daniel