perf evsel: Don't let evsel__group_pmu_name() traverse unsorted group

Previously the evsel__group_pmu_name would iterate the evsel's group,
however, the list of evsels aren't yet sorted and so the loop may
terminate prematurely. It is also not desirable to iterate the list of
evsels during list_sort as the list may be broken.

Precompute the group_pmu_name for the evsel before sorting, as part of
the computation and only if necessary, iterate the whole list looking
for group members so that being sorted isn't necessary.

Move the group pmu name computation to parse-events.c given the closer
dependency on the behavior of
parse_events__sort_events_and_fix_groups.

Fixes: 7abf0bcc ("perf evsel: Add function to compute group PMU name")
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Changbin Du <changbin.du@huawei.com>
Cc: Dmitrii Dolgov <9erthalion6@gmail.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Sandipan Das <sandipan.das@amd.com>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Link: https://lore.kernel.org/r/20230526194442.2355872-2-irogers@google.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/evsel.c

@@ -291,6 +291,7 @@ void evsel__init(struct evsel *evsel,
 	evsel->per_pkg_mask  = NULL;
 	evsel->collect_stat  = false;
 	evsel->pmu_name      = NULL;
+	evsel->group_pmu_name = NULL;
 	evsel->skippable     = false;
 }
 
@@ -391,6 +392,11 @@ struct evsel *evsel__clone(struct evsel *orig)
 		if (evsel->pmu_name == NULL)
 			goto out_err;
 	}
+	if (orig->group_pmu_name) {
+		evsel->group_pmu_name = strdup(orig->group_pmu_name);
+		if (evsel->group_pmu_name == NULL)
+			goto out_err;
+	}
 	if (orig->filter) {
 		evsel->filter = strdup(orig->filter);
 		if (evsel->filter == NULL)
@@ -787,30 +793,6 @@ bool evsel__name_is(struct evsel *evsel, const char *name)
 	return !strcmp(evsel__name(evsel), name);
 }
 
-const char *evsel__group_pmu_name(const struct evsel *evsel)
-{
-	struct evsel *leader = evsel__leader(evsel);
-	struct evsel *pos;
-
-	/*
-	 * Software events may be in a group with other uncore PMU events. Use
-	 * the pmu_name of the first non-software event to avoid breaking the
-	 * software event out of the group.
-	 *
-	 * Aux event leaders, like intel_pt, expect a group with events from
-	 * other PMUs, so substitute the AUX event's PMU in this case.
-	 */
-	if (evsel->core.attr.type == PERF_TYPE_SOFTWARE || evsel__is_aux_event(leader)) {
-		/* Starting with the leader, find the first event with a named PMU. */
-		for_each_group_evsel(pos, leader) {
-			if (pos->pmu_name)
-				return pos->pmu_name;
-		}
-	}
-
-	return evsel->pmu_name ?: "cpu";
-}
-
 const char *evsel__metric_id(const struct evsel *evsel)
 {
 	if (evsel->metric_id)
@@ -1492,6 +1474,7 @@ void evsel__exit(struct evsel *evsel)
 	zfree(&evsel->group_name);
 	zfree(&evsel->name);
 	zfree(&evsel->pmu_name);
+	zfree(&evsel->group_pmu_name);
 	zfree(&evsel->unit);
 	zfree(&evsel->metric_id);
 	evsel__zero_per_pkg(evsel);

tools/perf/util/evsel.h

@@ -72,6 +72,7 @@ struct evsel {
 		char			*name;
 		char			*group_name;
 		const char		*pmu_name;
+		const char		*group_pmu_name;
 #ifdef HAVE_LIBTRACEEVENT
 		struct tep_event	*tp_format;
 #endif
@@ -287,7 +288,6 @@ int arch_evsel__hw_name(struct evsel *evsel, char *bf, size_t size);
 int __evsel__hw_cache_type_op_res_name(u8 type, u8 op, u8 result, char *bf, size_t size);
 const char *evsel__name(struct evsel *evsel);
 bool evsel__name_is(struct evsel *evsel, const char *name);
-const char *evsel__group_pmu_name(const struct evsel *evsel);
 const char *evsel__metric_id(const struct evsel *evsel);
 
 static inline bool evsel__is_tool(const struct evsel *evsel)

tools/perf/util/parse-events.c

@@ -1984,6 +1984,42 @@ int parse_events_terms(struct list_head *terms, const char *str)
 	return ret;
 }
 
+static int evsel__compute_group_pmu_name(struct evsel *evsel,
+					  const struct list_head *head)
+{
+	struct evsel *leader = evsel__leader(evsel);
+	struct evsel *pos;
+	const char *group_pmu_name = evsel->pmu_name ?: "cpu";
+
+	/*
+	 * Software events may be in a group with other uncore PMU events. Use
+	 * the pmu_name of the first non-software event to avoid breaking the
+	 * software event out of the group.
+	 *
+	 * Aux event leaders, like intel_pt, expect a group with events from
+	 * other PMUs, so substitute the AUX event's PMU in this case.
+	 */
+	if (evsel->core.attr.type == PERF_TYPE_SOFTWARE || evsel__is_aux_event(leader)) {
+		/*
+		 * Starting with the leader, find the first event with a named
+		 * PMU. for_each_group_(member|evsel) isn't used as the list
+		 * isn't yet sorted putting evsel's in the same group together.
+		 */
+		if (leader->pmu_name) {
+			group_pmu_name = leader->pmu_name;
+		} else if (leader->core.nr_members > 1) {
+			list_for_each_entry(pos, head, core.node) {
+				if (evsel__leader(pos) == leader && pos->pmu_name) {
+					group_pmu_name = pos->pmu_name;
+					break;
+				}
+			}
+		}
+	}
+	evsel->group_pmu_name = strdup(group_pmu_name);
+	return evsel->group_pmu_name ? 0 : -ENOMEM;
+}
+
 __weak int arch_evlist__cmp(const struct evsel *lhs, const struct evsel *rhs)
 {
 	/* Order by insertion index. */
@@ -2003,7 +2039,11 @@ static int evlist__cmp(void *state, const struct list_head *l, const struct list
 
 	/*
 	 * First sort by grouping/leader. Read the leader idx only if the evsel
-	 * is part of a group, as -1 indicates no group.
+	 * is part of a group, by default ungrouped events will be sorted
+	 * relative to grouped events based on where the first ungrouped event
+	 * occurs. If both events don't have a group we want to fall-through to
+	 * the arch specific sorting, that can reorder and fix things like
+	 * Intel's topdown events.
 	 */
 	if (lhs_core->leader != lhs_core || lhs_core->nr_members > 1) {
 		lhs_has_group = true;
@@ -2019,8 +2059,8 @@ static int evlist__cmp(void *state, const struct list_head *l, const struct list
 
 	/* Group by PMU if there is a group. Groups can't span PMUs. */
 	if (lhs_has_group && rhs_has_group) {
-		lhs_pmu_name = evsel__group_pmu_name(lhs);
-		rhs_pmu_name = evsel__group_pmu_name(rhs);
+		lhs_pmu_name = lhs->group_pmu_name;
+		rhs_pmu_name = rhs->group_pmu_name;
 		ret = strcmp(lhs_pmu_name, rhs_pmu_name);
 		if (ret)
 			return ret;
@@ -2030,13 +2070,14 @@ static int evlist__cmp(void *state, const struct list_head *l, const struct list
 	return arch_evlist__cmp(lhs, rhs);
 }
 
-static bool parse_events__sort_events_and_fix_groups(struct list_head *list)
+static int parse_events__sort_events_and_fix_groups(struct list_head *list)
 {
 	int idx = 0, unsorted_idx = -1;
 	struct evsel *pos, *cur_leader = NULL;
 	struct perf_evsel *cur_leaders_grp = NULL;
 	bool idx_changed = false;
 	int orig_num_leaders = 0, num_leaders = 0;
+	int ret;
 
 	/*
 	 * Compute index to insert ungrouped events at. Place them where the
@@ -2045,6 +2086,10 @@ static bool parse_events__sort_events_and_fix_groups(struct list_head *list)
 	list_for_each_entry(pos, list, core.node) {
 		const struct evsel *pos_leader = evsel__leader(pos);
 
+		ret = evsel__compute_group_pmu_name(pos, list);
+		if (ret)
+			return ret;
+
 		if (pos == pos_leader)
 			orig_num_leaders++;
 
@@ -2069,7 +2114,7 @@ static bool parse_events__sort_events_and_fix_groups(struct list_head *list)
 	idx = 0;
 	list_for_each_entry(pos, list, core.node) {
 		const struct evsel *pos_leader = evsel__leader(pos);
-		const char *pos_pmu_name = evsel__group_pmu_name(pos);
+		const char *pos_pmu_name = pos->group_pmu_name;
 		const char *cur_leader_pmu_name, *pos_leader_pmu_name;
 		bool force_grouped = arch_evsel__must_be_in_group(pos);
 
@@ -2086,7 +2131,7 @@ static bool parse_events__sort_events_and_fix_groups(struct list_head *list)
 		if (!cur_leader)
 			cur_leader = pos;
 
-		cur_leader_pmu_name = evsel__group_pmu_name(cur_leader);
+		cur_leader_pmu_name = cur_leader->group_pmu_name;
 		if ((cur_leaders_grp != pos->core.leader && !force_grouped) ||
 		    strcmp(cur_leader_pmu_name, pos_pmu_name)) {
 			/* Event is for a different group/PMU than last. */
@@ -2098,7 +2143,7 @@ static bool parse_events__sort_events_and_fix_groups(struct list_head *list)
 			 */
 			cur_leaders_grp = pos->core.leader;
 		}
-		pos_leader_pmu_name = evsel__group_pmu_name(pos_leader);
+		pos_leader_pmu_name = pos_leader->group_pmu_name;
 		if (strcmp(pos_leader_pmu_name, pos_pmu_name) || force_grouped) {
 			/*
 			 * Event's PMU differs from its leader's. Groups can't
@@ -2115,7 +2160,7 @@ static bool parse_events__sort_events_and_fix_groups(struct list_head *list)
 			num_leaders++;
 		pos_leader->core.nr_members++;
 	}
-	return idx_changed || num_leaders != orig_num_leaders;
+	return (idx_changed || num_leaders != orig_num_leaders) ? 1 : 0;
 }
 
 int __parse_events(struct evlist *evlist, const char *str, const char *pmu_filter,
@@ -2132,7 +2177,7 @@ int __parse_events(struct evlist *evlist, const char *str, const char *pmu_filte
 		.pmu_filter = pmu_filter,
 		.match_legacy_cache_terms = true,
 	};
-	int ret;
+	int ret, ret2;
 
 	ret = parse_events__scanner(str, &parse_state);
 
@@ -2141,8 +2186,11 @@ int __parse_events(struct evlist *evlist, const char *str, const char *pmu_filte
 		return -1;
 	}
 
-	if (parse_events__sort_events_and_fix_groups(&parse_state.list) &&
-	    warn_if_reordered && !parse_state.wild_card_pmus)
+	ret2 = parse_events__sort_events_and_fix_groups(&parse_state.list);
+	if (ret2 < 0)
+		return ret;
+
+	if (ret2 && warn_if_reordered && !parse_state.wild_card_pmus)
 		pr_warning("WARNING: events were regrouped to match PMUs\n");
 
 	/*