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From:   Marco Elver <elver@google.com>
Date:   Sat, 3 Sep 2022 08:52:01 +0200
Message-ID: <CANpmjNMPh5QjdxXtrCc5FApjgzV=81CNNiwbeg_rE3NxN_WCZw@mail.gmail.com>
Subject: Re: [PATCH] perf test: Skip sigtrap test on old kernels
To:     Namhyung Kim <namhyung@kernel.org>
Cc:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Jiri Olsa <jolsa@kernel.org>, Ingo Molnar <mingo@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Ian Rogers <irogers@google.com>,
        linux-perf-users@vger.kernel.org
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On Sat, 3 Sept 2022 at 02:02, Namhyung Kim <namhyung@kernel.org> wrote:
>
> If it runs on an old kernel, perf_event_open would fail because of the
> new fields sigtrap and sig_data.  Just skip the test if it failed.
>
> Cc: Marco Elver <elver@google.com>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
>  tools/perf/tests/sigtrap.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/tools/perf/tests/sigtrap.c b/tools/perf/tests/sigtrap.c
> index e32ece90e164..7057566e6ae4 100644
> --- a/tools/perf/tests/sigtrap.c
> +++ b/tools/perf/tests/sigtrap.c
> @@ -140,6 +140,7 @@ static int test__sigtrap(struct test_suite *test __maybe_unused, int subtest __m
>         fd = sys_perf_event_open(&attr, 0, -1, -1, perf_event_open_cloexec_flag());
>         if (fd < 0) {
>                 pr_debug("FAILED sys_perf_event_open(): %s\n", str_error_r(errno, sbuf, sizeof(sbuf)));
> +               ret = TEST_SKIP;

Wouldn't we be interested if perf_event_open() fails because it could
actually be a bug? By skipping we'll be more likely to miss the fact
there's a real problem.

That's my naive thinking at least - what do other perf tests usually
do in this case?

Thanks,
-- Marco