On Tue, May 27, 2025 at 11:07:01AM -0700, Ian Rogers wrote:
> Reading through the evsel->evlist may seg fault if a sample arrives
> when the evlist is being deleted. Detect this case and ignore samples
> arriving when the evlist is being deleted.
Thanks, applied to perf-tools-next,
- Arnaldo
> Fixes: bcfab08db7fb ("perf intel-tpebs: Filter non-workload samples")
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
> tools/perf/util/intel-tpebs.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/util/intel-tpebs.c b/tools/perf/util/intel-tpebs.c
> index 4ad4bc118ea5..3b92ebf5c112 100644
> --- a/tools/perf/util/intel-tpebs.c
> +++ b/tools/perf/util/intel-tpebs.c
> @@ -162,9 +162,17 @@ static bool is_child_pid(pid_t parent, pid_t child)
>
> static bool should_ignore_sample(const struct perf_sample *sample, const struct tpebs_retire_lat *t)
> {
> - pid_t workload_pid = t->evsel->evlist->workload.pid;
> - pid_t sample_pid = sample->pid;
> + pid_t workload_pid, sample_pid = sample->pid;
>
> + /*
> + * During evlist__purge the evlist will be removed prior to the
> + * evsel__exit calling evsel__tpebs_close and taking the
> + * tpebs_mtx. Avoid a segfault by ignoring samples in this case.
> + */
> + if (t->evsel->evlist == NULL)
> + return true;
> +
> + workload_pid = t->evsel->evlist->workload.pid;
> if (workload_pid < 0 || workload_pid == sample_pid)
> return false;
>
> --
> 2.49.0.1204.g71687c7c1d-goog