netdev - Re: [PATCH v5 bpf-next 3/3] selftests/bpf: add raw_tp_test

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Date:   Fri, 25 Sep 2020 19:49:52 +0000
From:   Song Liu <songliubraving@...com>
To:     Andrii Nakryiko <andrii.nakryiko@...il.com>
CC:     Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        "Kernel Team" <Kernel-team@...com>,
        Alexei Starovoitov <ast@...nel.org>,
        "Daniel Borkmann" <daniel@...earbox.net>,
        john fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>
Subject: Re: [PATCH v5 bpf-next 3/3] selftests/bpf: add raw_tp_test_run



> On Sep 25, 2020, at 10:31 AM, Andrii Nakryiko <andrii.nakryiko@...il.com> wrote:
> 
> On Thu, Sep 24, 2020 at 4:03 PM Song Liu <songliubraving@...com> wrote:
>> 
>> This test runs test_run for raw_tracepoint program. The test covers ctx
>> input, retval output, and running on correct cpu.
>> 
>> Signed-off-by: Song Liu <songliubraving@...com>
>> ---
> 
> Few suggestions below, but overall looks good to me:
> 
> Acked-by: Andrii Nakryiko <andriin@...com>
> 
>> .../bpf/prog_tests/raw_tp_test_run.c          | 98 +++++++++++++++++++
>> .../bpf/progs/test_raw_tp_test_run.c          | 24 +++++
>> 2 files changed, 122 insertions(+)
>> create mode 100644 tools/testing/selftests/bpf/prog_tests/raw_tp_test_run.c
>> create mode 100644 tools/testing/selftests/bpf/progs/test_raw_tp_test_run.c
>> 
> 
> [...]
> 
>> +
>> +       err = bpf_prog_test_run_xattr(&test_attr);
>> +       CHECK(err == 0, "test_run", "should fail for too small ctx\n");
>> +
>> +       test_attr.ctx_size_in = sizeof(args);
>> +       err = bpf_prog_test_run_xattr(&test_attr);
>> +       CHECK(err < 0, "test_run", "err %d\n", errno);
>> +       CHECK(test_attr.retval != expected_retval, "check_retval",
>> +             "expect 0x%x, got 0x%x\n", expected_retval, test_attr.retval);
>> +
>> +       for (i = 0; i < nr_online; i++) {
>> +               if (online[i]) {
> 
> if (!online[i])
>    continue;
> 
> That will reduce nestedness by one level
> 
>> +                       DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts,
>> +                               .ctx_in = args,
>> +                               .ctx_size_in = sizeof(args),
>> +                               .flags = BPF_F_TEST_RUN_ON_CPU,
>> +                               .retval = 0,
>> +                               .cpu = i,
>> +                       );
> 
> this declares variable, so should be at the top of the lexical scope
> 
> 
>> +
>> +                       err = bpf_prog_test_run_opts(prog_fd, &opts);
>> +                       CHECK(err < 0, "test_run_opts", "err %d\n", errno);
>> +                       CHECK(skel->data->on_cpu != i, "check_on_cpu",
>> +                             "expect %d got %d\n", i, skel->data->on_cpu);
>> +                       CHECK(opts.retval != expected_retval,
>> +                             "check_retval", "expect 0x%x, got 0x%x\n",
>> +                             expected_retval, opts.retval);
>> +
>> +                       if (i == 0) {
> 
> I agree that this looks a bit obscure. You can still re-use
> DECLARE_LIBBPF_OPTS, just move it outside the loop. And then you can
> just modify it in place to adjust to a particular case. And in log
> output, we'll see 30+ similar success messages for the else branch,
> which is indeed unnecessary.

OK.. 2:1, I will change this in v6. 

Thanks,
Song