Re: [PATCH 2/2] perf tools: Ignore dead threads during event synthesis

Ian Rogers
2022-07-01T23:06:41Z

On Fri, Jul 1, 2022 at 1:55 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> When it synthesize various task events, it scans the list of task
> first and then accesses later. There's a window threads can die
> between the two and proc entries may not be available.
>
> Instead of bailing out, we can ignore that thread and move on.
>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Acked-by: Ian Rogers <irogers@google.com>

Thanks,
Ian

> ---
> tools/perf/util/synthetic-events.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
> index a068f42833c3..84d17bd4efae 100644
> --- a/tools/perf/util/synthetic-events.c
> +++ b/tools/perf/util/synthetic-events.c
> @@ -767,11 +767,12 @@ static int __event__synthesize_thread(union perf_event *comm_event,
> if (*end)
> continue;
>
> - rc = -1;
> + /* some threads may exit just after scan, ignore it */
> if (perf_event__prepare_comm(comm_event, pid, _pid, machine,
> &tgid, &ppid, &kernel_thread) != 0)
> - break;
> + continue;
>
> + rc = -1;
> if (perf_event__synthesize_fork(tool, fork_event, _pid, tgid,
> ppid, process, machine) < 0)
> break;
> --
> 2.37.0.rc0.161.g10f37bed90-goog
>