[PATCH] perf metrics: Fixes stat cmd cannot parse sys metrics when cpus MIDR mismatch

[Junhao He <hejunhao3@huawei.com>]

On some platforms that do not use cpu MIDR mapping, such as hisilicon
HIP09 platform. The list cmd can display the CPA metrics, but the stat
cmd cannot work well to parse of CPA metrics.

  $ perf list metric
  Metrics:
    cpa_p0_avg_bw
         [Average bandwidth of CPA Port 0]
    cpa_p1_avg_bw
         [Average bandwidth of CPA Port 1]
  $ perf stat -M cpa_p0_avg_bw --timeout 1000 --> No error messages output
  $ echo $?
  234

Currently, the metricgroup__parse_groups() expects to find an cpu metric
table, but the hisilicon/hip09 doesn't uses cpus MIDR to map json events
and metrics, so pmu_metrics_table__find() will return NULL, than the cmd
run failed.
But in metricgroup__add_metric(), the function parse for each sys metric
and add it to metric_list, which also will get an valid sys metric table.
So, we can ignore the NULL result of pmu_metrics_table__find() and to use
the sys metric table.

metricgroup__parse_groups
 -> parse_groups
     -> metricgroup__add_metric_list
         -> metricgroup__add_metric
             -> pmu_for_each_sys_metric   --> We've got the sys metric

Testing:
  [root@localhost ~]# perf stat -M cpa_p0_avg_bw --no-merge --timeout 1000

   Performance counter stats for 'system wide':

   CPU0        1,001,121,239      cpa_cycles [hisi_sicl0_cpa0]     #     0.00 cpa_p0_avg_bw
   CPU0                    0      cpa_p0_wr_dat [hisi_sicl0_cpa0]
   CPU0                    0      cpa_p0_rd_dat_64b [hisi_sicl0_cpa0]
   CPU0                    0      cpa_p0_rd_dat_32b [hisi_sicl0_cpa0]
   CPU0        1,001,094,851      cpa_cycles [hisi_sicl2_cpa0]     #     0.00 cpa_p0_avg_bw
   CPU0                    0      cpa_p0_wr_dat [hisi_sicl2_cpa0]
   CPU0                    0      cpa_p0_rd_dat_64b [hisi_sicl2_cpa0]
   CPU0                    0      cpa_p0_rd_dat_32b [hisi_sicl2_cpa0]

       1.001306160 seconds time elapsed

Signed-off-by: Junhao He <hejunhao3@huawei.com>
---
 tools/perf/util/metricgroup.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
index 69f6a46402c3..fa62fb3418b6 100644
--- a/tools/perf/util/metricgroup.c
+++ b/tools/perf/util/metricgroup.c
@@ -1123,7 +1123,7 @@ static int metricgroup__add_metric_sys_event_iter(const struct pmu_metric *pm,
 
 	ret = add_metric(d->metric_list, pm, d->modifier, d->metric_no_group,
 			 d->metric_no_threshold, d->user_requested_cpu_list,
-			 d->system_wide, d->root_metric, d->visited, d->table);
+			 d->system_wide, d->root_metric, d->visited, d->table ?: table);
 	if (ret)
 		goto out;
 
@@ -1239,7 +1239,7 @@ static int metricgroup__add_metric(const char *pmu, const char *metric_name, con
 	int ret;
 	bool has_match = false;
 
-	{
+	if (table) {
 		struct metricgroup__add_metric_data data = {
 			.list = &list,
 			.pmu = pmu,
@@ -1696,8 +1696,6 @@ int metricgroup__parse_groups(struct evlist *perf_evlist,
 {
 	const struct pmu_metrics_table *table = pmu_metrics_table__find();
 
-	if (!table)
-		return -EINVAL;
 	if (hardware_aware_grouping)
 		pr_debug("Use hardware aware grouping instead of traditional metric grouping method\n");
 
-- 
2.33.0