[PATCH] perf metricgroup: Fix system PMU metrics

From: John Garry
Date: Tue Jan 19 2021 - 05:26:08 EST

Joakim reports that getting "perf stat" for multiple system PMU metrics
./perf stat -a -I 1000 -M imx8mm_ddr_write.all,imx8mm_ddr_write.all
Segmentation fault

While the same works without issue for a single metric.

The logic in metricgroup__add_metric_sys_event_iter() is broken, in that
add_metric() @m argument should be NULL for each new metric. Fix by not
passing a holder for that, and rather make local in

Fixes: be335ec28efa ("perf metricgroup: Support adding metrics for system PMUs")
Reported-by: Joakim Zhang <qiangqing.zhang@xxxxxxx>
Signed-off-by: John Garry <john.garry@xxxxxxxxxx>

diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
index ee94d3e8dd65..2e60ee170abc 100644
--- a/tools/perf/util/metricgroup.c
+++ b/tools/perf/util/metricgroup.c
@@ -766,7 +766,6 @@ int __weak arch_get_runtimeparam(struct pmu_event *pe __maybe_unused)
struct metricgroup_add_iter_data {
struct list_head *metric_list;
const char *metric;
- struct metric **m;
struct expr_ids *ids;
int *ret;
bool *has_match;
@@ -1058,12 +1057,13 @@ static int metricgroup__add_metric_sys_event_iter(struct pmu_event *pe,
void *data)
struct metricgroup_add_iter_data *d = data;
+ struct metric *m = NULL;
int ret;

if (!match_pe_metric(pe, d->metric))
return 0;

- ret = add_metric(d->metric_list, pe, d->metric_no_group, d->m, NULL, d->ids);
+ ret = add_metric(d->metric_list, pe, d->metric_no_group, &m, NULL, d->ids);
if (ret)
return ret;

@@ -1114,7 +1114,6 @@ static int metricgroup__add_metric(const char *metric, bool metric_no_group,
.metric_list = &list,
.metric = metric,
.metric_no_group = metric_no_group,
- .m = &m,
.ids = &ids,
.has_match = &has_match,
.ret = &ret,