perf metrics: Fix segv for metrics with no events

A metric may have no events, for example, the transaction metrics on
x86 are dependent on there being TSX events. Fix a segv where an evsel
of NULL is dereferenced for a metric leader value.

Fixes: a59fb796a36b ("perf metrics: Compute unmerged uncore metrics individually")
Signed-off-by: Ian Rogers <irogers@google.com>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240224011420.3066322-2-irogers@google.com

diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
index 2d6865c392ef46e99a5b4695e94dafd95a862529..79ef6095ab28919c564e0d6000a4f503129e8305 100644 (file)
--- a/tools/perf/util/metricgroup.c
+++ b/tools/perf/util/metricgroup.c
@@ -44,7 +44,7 @@ struct metric_event *metricgroup__lookup(struct rblist *metric_events,
        if (!metric_events)
                return NULL;
 
-       if (evsel->metric_leader)
+       if (evsel && evsel->metric_leader)
                me.evsel = evsel->metric_leader;
        nd = rblist__find(metric_events, &me);
        if (nd)