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From:   Andrii Nakryiko <andrii.nakryiko@gmail.com>
Date:   Thu, 3 Sep 2020 11:50:46 -0700
Message-ID: <CAEf4BzYtr6Tki8viGt0KBAwH5FF0don+j3Td86m0Kg95kUEAhw@mail.gmail.com>
Subject: Re: [PATCH] selftests/bpf: Fix check in global_data_init.
To:     Hao Luo <haoluo@google.com>
Cc:     Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@vger.kernel.org>, Shuah Khan <shuah@kernel.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Andrii Nakryiko <andriin@fb.com>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= <toke@redhat.com>,
        KP Singh <kpsingh@chromium.org>
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On Thu, Sep 3, 2020 at 11:02 AM Hao Luo <haoluo@google.com> wrote:
>
> The returned value of bpf_object__open_file() should be checked with
> IS_ERR() rather than NULL. This fix makes test_progs not crash when
> test_global_data.o is not present.
>
> Signed-off-by: Hao Luo <haoluo@google.com>
> ---
>  tools/testing/selftests/bpf/prog_tests/global_data_init.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/global_data_init.c b/tools/testing/selftests/bpf/prog_tests/global_data_init.c
> index 3bdaa5a40744..1ece86d5c519 100644
> --- a/tools/testing/selftests/bpf/prog_tests/global_data_init.c
> +++ b/tools/testing/selftests/bpf/prog_tests/global_data_init.c
> @@ -12,7 +12,7 @@ void test_global_data_init(void)
>         size_t sz;
>
>         obj = bpf_object__open_file(file, NULL);
> -       if (CHECK_FAIL(!obj))
> +       if (CHECK_FAIL(IS_ERR(obj)))

Can you please use libbpf_get_error(obj) instead to set a good example
or not relying on kernel internal macros?

>                 return;
>
>         map = bpf_object__find_map_by_name(obj, "test_glo.rodata");
> --
> 2.28.0.402.g5ffc5be6b7-goog
>