netdev - Re: [PATCH bpf-next v4 2/3] bpf: selftests: remove percpu macros from bpf

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Message-ID: <CAADnVQ+XtLj2vUmfazYu8-k3+bd0bJFJUTZWGRBALV1xy-vqFg@mail.gmail.com>
Date:   Mon, 19 Apr 2021 18:17:18 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Pedro Tammela <pctammela@...il.com>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>, Shuah Khan <shuah@...nel.org>,
        Pedro Tammela <pctammela@...atatu.com>,
        David Verbeiren <david.verbeiren@...sares.net>,
        Matthieu Baerts <matthieu.baerts@...sares.net>,
        Network Development <netdev@...r.kernel.org>,
        bpf <bpf@...r.kernel.org>
Subject: Re: [PATCH bpf-next v4 2/3] bpf: selftests: remove percpu macros from bpf_util.h

On Thu, Apr 15, 2021 at 10:47 AM Pedro Tammela <pctammela@...il.com> wrote:
>
> Andrii suggested to remove this abstraction layer and have the percpu
> handling more explicit[1].
>
> This patch also updates the tests that relied on the macros.
>
> [1] https://lore.kernel.org/bpf/CAEf4BzYmj_ZPDq8Zi4dbntboJKRPU2TVopysBNrdd9foHTfLZw@mail.gmail.com/
>
> Suggested-by: Andrii Nakryiko <andrii@...nel.org>
> Signed-off-by: Pedro Tammela <pctammela@...atatu.com>
> ---
>  tools/testing/selftests/bpf/bpf_util.h        |  7 --
>  .../bpf/map_tests/htab_map_batch_ops.c        | 87 +++++++++----------
>  .../selftests/bpf/prog_tests/map_init.c       |  9 +-
>  tools/testing/selftests/bpf/test_maps.c       | 84 +++++++++++-------
>  4 files changed, 96 insertions(+), 91 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/bpf_util.h b/tools/testing/selftests/bpf/bpf_util.h
> index a3352a64c067..105db3120ab4 100644
> --- a/tools/testing/selftests/bpf/bpf_util.h
> +++ b/tools/testing/selftests/bpf/bpf_util.h
> @@ -20,13 +20,6 @@ static inline unsigned int bpf_num_possible_cpus(void)
>         return possible_cpus;
>  }
>
> -#define __bpf_percpu_val_align __attribute__((__aligned__(8)))
> -
> -#define BPF_DECLARE_PERCPU(type, name)                         \
> -       struct { type v; /* padding */ } __bpf_percpu_val_align \
> -               name[bpf_num_possible_cpus()]
> -#define bpf_percpu(name, cpu) name[(cpu)].v
> -

Hmm. I wonder what Daniel has to say about it, since he
introduced it in commit f3515b5d0b71 ("bpf: provide a generic macro
for percpu values for selftests")
to address a class of bugs.