perf parse-events: Copy fewer term lists

When trying to add events to multiple PMUs the term list is copied first
as adding the event will rewrite the event's name term into the sysfs
and/or json encoding terms (see perf_pmu__check_alias).

Change the parse events add API so the passed in term list is const,
then copy the list when modification is necessary.

Reviewed-by: James Clark <[e-mail]>
Signed-off-by: Ian Rogers <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Kan Liang <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Rob Herring <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/parse-events.c

···
 extern int parse_events_debug;
 #endif
 static int get_config_terms(struct list_head *head_config, struct list_head *head_terms);
+static int parse_events_terms__copy(const struct list_head *src, struct list_head *dest);
 
 struct event_symbol event_symbols_hw[PERF_COUNT_HW_MAX] = {
 	[PERF_COUNT_HW_CPU_CYCLES] = {
···
 
 int parse_events_add_pmu(struct parse_events_state *parse_state,
 			 struct list_head *list, const char *name,
-			 struct list_head *head_config,
+			 const struct list_head *const_head_terms,
 			 bool auto_merge_stats, void *loc_)
 {
 	struct perf_event_attr attr;
···
 	struct parse_events_error *err = parse_state->error;
 	YYLTYPE *loc = loc_;
 	LIST_HEAD(config_terms);
+	LIST_HEAD(head_terms);
 
 	pmu = parse_state->fake_pmu ?: perf_pmus__find(name);
 
···
 		return -EINVAL;
 	}
 
+	if (const_head_terms) {
+		int ret = parse_events_terms__copy(const_head_terms, &head_terms);
+
+		if (ret)
+			return ret;
+	}
+
 	if (verbose > 1) {
 		struct strbuf sb;
 
 		strbuf_init(&sb, /*hint=*/ 0);
-		if (pmu->selectable && !head_config) {
+		if (pmu->selectable && list_empty(&head_terms)) {
 			strbuf_addf(&sb, "%s//", name);
 		} else {
 			strbuf_addf(&sb, "%s/", name);
-			parse_events_term__to_strbuf(head_config, &sb);
+			parse_events_term__to_strbuf(&head_terms, &sb);
 			strbuf_addch(&sb, '/');
 		}
 		fprintf(stderr, "Attempt to add: %s\n", sb.buf);
 		strbuf_release(&sb);
 	}
-	if (head_config)
-		fix_raw(head_config, pmu);
+	fix_raw(&head_terms, pmu);
 
 	if (pmu->default_config) {
-		memcpy(&attr, pmu->default_config,
-		       sizeof(struct perf_event_attr));
+		memcpy(&attr, pmu->default_config, sizeof(struct perf_event_attr));
 	} else {
 		memset(&attr, 0, sizeof(attr));
 	}
 	attr.type = pmu->type;
 
-	if (!head_config) {
+	if (list_empty(&head_terms)) {
 		evsel = __add_event(list, &parse_state->idx, &attr,
 				    /*init_attr=*/true, /*name=*/NULL,
 				    /*metric_id=*/NULL, pmu,
···
 		return evsel ? 0 : -ENOMEM;
 	}
 
-	if (!parse_state->fake_pmu && perf_pmu__check_alias(pmu, head_config, &info, err))
+	if (!parse_state->fake_pmu && perf_pmu__check_alias(pmu, &head_terms, &info, err)) {
+		parse_events_terms__purge(&head_terms);
 		return -EINVAL;
+	}
 
 	if (verbose > 1) {
 		struct strbuf sb;
 
 		strbuf_init(&sb, /*hint=*/ 0);
-		parse_events_term__to_strbuf(head_config, &sb);
+		parse_events_term__to_strbuf(&head_terms, &sb);
 		fprintf(stderr, "..after resolving event: %s/%s/\n", name, sb.buf);
 		strbuf_release(&sb);
 	}
···
 	 * Configure hardcoded terms first, no need to check
 	 * return value when called with fail == 0 ;)
 	 */
-	if (config_attr(&attr, head_config, parse_state->error, config_term_pmu))
+	if (config_attr(&attr, &head_terms, parse_state->error, config_term_pmu)) {
+		parse_events_terms__purge(&head_terms);
 		return -EINVAL;
+	}
 
-	if (get_config_terms(head_config, &config_terms))
+	if (get_config_terms(&head_terms, &config_terms)) {
+		parse_events_terms__purge(&head_terms);
 		return -ENOMEM;
+	}
 
 	/*
 	 * When using default config, record which bits of attr->config were
 	 * changed by the user.
 	 */
-	if (pmu->default_config && get_config_chgs(pmu, head_config, &config_terms))
+	if (pmu->default_config && get_config_chgs(pmu, &head_terms, &config_terms)) {
+		parse_events_terms__purge(&head_terms);
 		return -ENOMEM;
+	}
 
-	if (!parse_state->fake_pmu && perf_pmu__config(pmu, &attr, head_config, parse_state->error)) {
+	if (!parse_state->fake_pmu &&
+	    perf_pmu__config(pmu, &attr, &head_terms, parse_state->error)) {
 		free_config_terms(&config_terms);
+		parse_events_terms__purge(&head_terms);
 		return -EINVAL;
 	}
 
 	evsel = __add_event(list, &parse_state->idx, &attr, /*init_attr=*/true,
-			    get_config_name(head_config),
-			    get_config_metric_id(head_config), pmu,
+			    get_config_name(&head_terms),
+			    get_config_metric_id(&head_terms), pmu,
 			    &config_terms, auto_merge_stats, /*cpu_list=*/NULL);
-	if (!evsel)
+	if (!evsel) {
+		parse_events_terms__purge(&head_terms);
 		return -ENOMEM;
+	}
 
 	if (evsel->name)
 		evsel->use_config_name = true;
 
 	evsel->percore = config_term_percore(&evsel->config_terms);
 
-	if (parse_state->fake_pmu)
+	if (parse_state->fake_pmu) {
+		parse_events_terms__purge(&head_terms);
 		return 0;
+	}
 
+	parse_events_terms__purge(&head_terms);
 	free((char *)evsel->unit);
 	evsel->unit = strdup(info.unit);
 	evsel->scale = info.scale;
···
 }
 
 int parse_events_multi_pmu_add(struct parse_events_state *parse_state,
-			       const char *event_name, struct list_head *head,
+			       const char *event_name,
+			       const struct list_head *const_head_terms,
 			       struct list_head **listp, void *loc_)
 {
 	struct parse_events_term *term;
 	struct list_head *list = NULL;
-	struct list_head *orig_head = NULL;
 	struct perf_pmu *pmu = NULL;
 	YYLTYPE *loc = loc_;
 	int ok = 0;
 	const char *config;
+	LIST_HEAD(head_terms);
 
 	*listp = NULL;
 
-	if (!head) {
-		head = malloc(sizeof(struct list_head));
-		if (!head)
-			goto out_err;
+	if (const_head_terms) {
+		int ret = parse_events_terms__copy(const_head_terms, &head_terms);
 
-		INIT_LIST_HEAD(head);
+		if (ret)
+			return ret;
 	}
 
 	config = strdup(event_name);
···
 		zfree(&config);
 		goto out_err;
 	}
-	list_add_tail(&term->list, head);
+	list_add_tail(&term->list, &head_terms);
 
 	/* Add it for all PMUs that support the alias */
 	list = malloc(sizeof(struct list_head));
···
 			continue;
 
 		auto_merge_stats = perf_pmu__auto_merge_stats(pmu);
-		parse_events_copy_term_list(head, &orig_head);
 		if (!parse_events_add_pmu(parse_state, list, pmu->name,
-					  orig_head, auto_merge_stats, loc)) {
+					  &head_terms, auto_merge_stats, loc)) {
 			struct strbuf sb;
 
 			strbuf_init(&sb, /*hint=*/ 0);
-			parse_events_term__to_strbuf(orig_head, &sb);
+			parse_events_term__to_strbuf(&head_terms, &sb);
 			pr_debug("%s -> %s/%s/\n", event_name, pmu->name, sb.buf);
 			strbuf_release(&sb);
 			ok++;
 		}
-		parse_events_terms__delete(orig_head);
 	}
 
 	if (parse_state->fake_pmu) {
-		if (!parse_events_add_pmu(parse_state, list, event_name, head,
+		if (!parse_events_add_pmu(parse_state, list, event_name, &head_terms,
 					  /*auto_merge_stats=*/true, loc)) {
 			struct strbuf sb;
 
 			strbuf_init(&sb, /*hint=*/ 0);
-			parse_events_term__to_strbuf(head, &sb);
+			parse_events_term__to_strbuf(&head_terms, &sb);
 			pr_debug("%s -> %s/%s/\n", event_name, "fake_pmu", sb.buf);
 			strbuf_release(&sb);
 			ok++;
···
 	}
 
 out_err:
+	parse_events_terms__purge(&head_terms);
 	if (ok)
 		*listp = list;
 	else
 		free(list);
 
-	parse_events_terms__delete(head);
 	return ok ? 0 : -1;
 }
 
···
 	free(term);
 }
 
-int parse_events_copy_term_list(struct list_head *old,
-				 struct list_head **new)
+static int parse_events_terms__copy(const struct list_head *src, struct list_head *dest)
 {
-	struct parse_events_term *term, *n;
-	int ret;
+	struct parse_events_term *term;
 
-	if (!old) {
-		*new = NULL;
-		return 0;
-	}
+	list_for_each_entry (term, src, list) {
+		struct parse_events_term *n;
+		int ret;
 
-	*new = malloc(sizeof(struct list_head));
-	if (!*new)
-		return -ENOMEM;
-	INIT_LIST_HEAD(*new);
-
-	list_for_each_entry (term, old, list) {
 		ret = parse_events_term__clone(&n, term);
 		if (ret)
 			return ret;
-		list_add_tail(&n->list, *new);
+
+		list_add_tail(&n->list, dest);
 	}
 	return 0;
 }

tools/perf/util/parse-events.h

···
 				struct list_head *head_config);
 int parse_events_add_pmu(struct parse_events_state *parse_state,
 			 struct list_head *list, const char *name,
-			 struct list_head *head_config,
+			 const struct list_head *const_head_terms,
 			bool auto_merge_stats, void *loc);
 
 struct evsel *parse_events__add_event(int idx, struct perf_event_attr *attr,
···
 
 int parse_events_multi_pmu_add(struct parse_events_state *parse_state,
 			       const char *event_name,
-			       struct list_head *head_config,
+			       const struct list_head *head_terms,
 			       struct list_head **listp, void *loc);
-
-int parse_events_copy_term_list(struct list_head *old,
-				 struct list_head **new);
 
 void parse_events__set_leader(char *name, struct list_head *list);
 void parse_events_update_lists(struct list_head *list_event,

tools/perf/util/parse-events.y

···
 PE_NAME opt_pmu_config
 {
 	struct parse_events_state *parse_state = _parse_state;
-	struct list_head *list = NULL, *orig_terms = NULL, *terms= NULL;
+	/* List of created evsels. */
+	struct list_head *list = NULL;
 	char *pattern = NULL;
 
 #define CLEANUP						\
 	do {						\
 		parse_events_terms__delete($2);		\
-		parse_events_terms__delete(orig_terms);	\
 		free(list);				\
 		free($1);				\
 		free(pattern);				\
 	} while(0)
-
-	if (parse_events_copy_term_list($2, &orig_terms)) {
-		CLEANUP;
-		YYNOMEM;
-	}
 
 	list = alloc_list();
 	if (!list) {
···
 			    !perf_pmu__match(pattern, pmu->alias_name, $1)) {
 				bool auto_merge_stats = perf_pmu__auto_merge_stats(pmu);
 
-				if (parse_events_copy_term_list(orig_terms, &terms)) {
-					CLEANUP;
-					YYNOMEM;
-				}
-				if (!parse_events_add_pmu(parse_state, list, pmu->name, terms,
+				if (!parse_events_add_pmu(parse_state, list, pmu->name, $2,
 							  auto_merge_stats, &@1)) {
 					ok++;
 					parse_state->wild_card_pmus = true;
 				}
-				parse_events_terms__delete(terms);
 			}
 		}
 
···
 			/* Failure to add, assume $1 is an event name. */
 			zfree(&list);
 			ok = !parse_events_multi_pmu_add(parse_state, $1, $2, &list, &@1);
-			$2 = NULL;
 		}
 		if (!ok) {
 			struct parse_events_error *error = parse_state->error;