perf tracepoint: Sort events in iterator

In print_tracepoint_events() use tracing_events__scandir_alphasort() and
scandir alphasort so that the subsystem and events are sorted and don't
need a secondary qsort. Locally this results in the following change:

...
   ext4:ext4_zero_range                               [Tracepoint event]
-  fib6:fib6_table_lookup                             [Tracepoint event]
   fib:fib_table_lookup                               [Tracepoint event]
+  fib6:fib6_table_lookup                             [Tracepoint event]
   filelock:break_lease_block                         [Tracepoint event]
...

ie fib6 now is after fib and not before it. This is more consistent
with how numbers are more generally sorted, such as:

...
  syscalls:sys_enter_renameat                        [Tracepoint event]
  syscalls:sys_enter_renameat2                       [Tracepoint event]
...

and so an improvement over the qsort approach.
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Caleb Biggers <caleb.biggers@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Perry Taylor <perry.taylor@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Sandipan Das <sandipan.das@amd.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Weilin Wang <weilin.wang@intel.com>
Cc: Xin Gao <gaoxin@cdjrlc.com>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Link: http://lore.kernel.org/lkml/20221114210723.2749751-5-irogers@google.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/print-events.c

@@ -66,26 +66,21 @@ static int cmp_string(const void *a, const void *b)
 void print_tracepoint_events(const char *subsys_glob,
 			     const char *event_glob, bool name_only)
 {
-	DIR *sys_dir, *evt_dir;
-	struct dirent *sys_dirent, *evt_dirent;
-	char evt_path[MAXPATHLEN];
-	char *dir_path;
-	char **evt_list = NULL;
-	unsigned int evt_i = 0, evt_num = 0;
-	bool evt_num_known = false;
-
-restart:
-	sys_dir = tracing_events__opendir();
-	if (!sys_dir)
-		return;
-
-	if (evt_num_known) {
-		evt_list = zalloc(sizeof(char *) * evt_num);
-		if (!evt_list)
-			goto out_close_sys_dir;
-	}
+	struct dirent **sys_namelist = NULL;
+	bool printed = false;
+	int sys_items = tracing_events__scandir_alphasort(&sys_namelist);
+
+	for (int i = 0; i < sys_items; i++) {
+		struct dirent *sys_dirent = sys_namelist[i];
+		struct dirent **evt_namelist = NULL;
+		char *dir_path;
+		int evt_items;
+
+		if (sys_dirent->d_type != DT_DIR ||
+		    !strcmp(sys_dirent->d_name, ".") ||
+		    !strcmp(sys_dirent->d_name, ".."))
+			continue;
 
-	for_each_subsystem(sys_dir, sys_dirent) {
 		if (subsys_glob != NULL &&
 		    !strglobmatch(sys_dirent->d_name, subsys_glob))
 			continue;
@@ -93,69 +88,40 @@ void print_tracepoint_events(const char *subsys_glob,
 		dir_path = get_events_file(sys_dirent->d_name);
 		if (!dir_path)
 			continue;
-		evt_dir = opendir(dir_path);
-		if (!evt_dir)
-			goto next;
 
-		for_each_event(dir_path, evt_dir, evt_dirent) {
-			if (event_glob != NULL &&
-			    !strglobmatch(evt_dirent->d_name, event_glob))
+		evt_items = scandir(dir_path, &evt_namelist, NULL, alphasort);
+		for (int j = 0; j < evt_items; j++) {
+			struct dirent *evt_dirent = evt_namelist[j];
+			char evt_path[MAXPATHLEN];
+
+			if (evt_dirent->d_type != DT_DIR ||
+			    !strcmp(evt_dirent->d_name, ".") ||
+			    !strcmp(evt_dirent->d_name, ".."))
 				continue;
 
-			if (!evt_num_known) {
-				evt_num++;
+			if (tp_event_has_id(dir_path, evt_dirent) != 0)
+				continue;
+
+			if (event_glob != NULL &&
+			    !strglobmatch(evt_dirent->d_name, event_glob))
 				continue;
-			}
 
 			snprintf(evt_path, MAXPATHLEN, "%s:%s",
 				 sys_dirent->d_name, evt_dirent->d_name);
-
-			evt_list[evt_i] = strdup(evt_path);
-			if (evt_list[evt_i] == NULL) {
-				put_events_file(dir_path);
-				goto out_close_evt_dir;
+			if (name_only)
+				printf("%s ", evt_path);
+			else {
+				printf("  %-50s [%s]\n", evt_path,
+				       event_type_descriptors[PERF_TYPE_TRACEPOINT]);
 			}
-			evt_i++;
+			printed = true;
 		}
-		closedir(evt_dir);
-next:
-		put_events_file(dir_path);
+		free(dir_path);
+		free(evt_namelist);
 	}
-	closedir(sys_dir);
-
-	if (!evt_num_known) {
-		evt_num_known = true;
-		goto restart;
-	}
-	qsort(evt_list, evt_num, sizeof(char *), cmp_string);
-	evt_i = 0;
-	while (evt_i < evt_num) {
-		if (name_only) {
-			printf("%s ", evt_list[evt_i++]);
-			continue;
-		}
-		printf("  %-50s [%s]\n", evt_list[evt_i++],
-				event_type_descriptors[PERF_TYPE_TRACEPOINT]);
-	}
-	if (evt_num && pager_in_use())
+	free(sys_namelist);
+	if (printed && pager_in_use())
 		printf("\n");
-
-out_free:
-	evt_num = evt_i;
-	for (evt_i = 0; evt_i < evt_num; evt_i++)
-		zfree(&evt_list[evt_i]);
-	zfree(&evt_list);
-	return;
-
-out_close_evt_dir:
-	closedir(evt_dir);
-out_close_sys_dir:
-	closedir(sys_dir);
-
-	printf("FATAL: not enough memory to print %s\n",
-			event_type_descriptors[PERF_TYPE_TRACEPOINT]);
-	if (evt_list)
-		goto out_free;
 }
 
 void print_sdt_events(const char *subsys_glob, const char *event_glob,