perf metricgroup: Use early return in add_metric

Use early return in metricgroup__add_metric and try to make the intent
of the returns more intention revealing.
Suggested-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andrii Nakryiko <andriin@fb.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Kim Phillips <kim.phillips@amd.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Clarke <pc@us.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: bpf@vger.kernel.org
Cc: netdev@vger.kernel.org
Link: http://lore.kernel.org/lkml/20200520182011.32236-3-irogers@google.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/metricgroup.c

@@ -527,7 +527,8 @@ static int metricgroup__add_metric(const char *metric, struct strbuf *events,
 {
 	struct pmu_events_map *map = perf_pmu__find_map(NULL);
 	struct pmu_event *pe;
-	int i, ret = -EINVAL;
+	int i, ret;
+	bool has_match = false;
 
 	if (!map)
 		return 0;
@@ -535,17 +536,23 @@ static int metricgroup__add_metric(const char *metric, struct strbuf *events,
 	for (i = 0; ; i++) {
 		pe = &map->table[i];
 
-		if (!pe->name && !pe->metric_group && !pe->metric_name)
+		if (!pe->name && !pe->metric_group && !pe->metric_name) {
+			/* End of pmu events. */
+			if (!has_match)
+				return -EINVAL;
 			break;
+		}
 		if (!pe->metric_expr)
 			continue;
 		if (match_metric(pe->metric_group, metric) ||
 		    match_metric(pe->metric_name, metric)) {
-
+			has_match = true;
 			pr_debug("metric expr %s for %s\n", pe->metric_expr, pe->metric_name);
 
 			if (!strstr(pe->metric_expr, "?")) {
 				ret = __metricgroup__add_metric(events, group_list, pe, 1);
+				if (ret)
+					return ret;
 			} else {
 				int j, count;
 
@@ -556,14 +563,15 @@ static int metricgroup__add_metric(const char *metric, struct strbuf *events,
 				 * those events to group_list.
 				 */
 
-				for (j = 0; j < count; j++)
+				for (j = 0; j < count; j++) {
 					ret = __metricgroup__add_metric(events, group_list, pe, j);
+					if (ret)
+						return ret;
+				}
 			}
-			if (ret == -ENOMEM)
-				break;
 		}
 	}
-	return ret;
+	return 0;
 }
 
 static int metricgroup__add_metric_list(const char *list, struct strbuf *events,