perf test: Iterate over shell tests in alphabetical order

The for_each_shell_test macro iterated over all shell tests in the
directory using readdir, which does not guarantee any ordering, causing
problems on certain fs. However, the order in which they are visited
determines the id of the test, in case one wants to run a single test.

This patch replaces readdir with scandir using alphabetical sorting.
This guarantees that, given the same set of tests, all machines will
see the tests in the same order, and, thus, that test ids are
consistent.

Signed-off-by: Riccardo Mancini <rickyman7@gmail.com>
Reported-by: Ian Rogers <irogers@google.com>
Acked-by: Ian Rogers <irogers@google.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Fabian Hemmer <copy@copy.sh>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tommi Rantala <tommi.t.rantala@nokia.com>
Link: http://lore.kernel.org/lkml/20210525230521.244553-1-rickyman7@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/builtin-test.c

@@ -510,8 +510,8 @@ static const char *shell_test__description(char *description, size_t size,
 	return description ? strim(description + 1) : NULL;
 }
 
-#define for_each_shell_test(dir, base, ent)	\
-	while ((ent = readdir(dir)) != NULL)	\
+#define for_each_shell_test(entlist, nr, base, ent)	                \
+	for (int __i = 0; __i < nr && (ent = entlist[__i]); __i++)	\
 		if (!is_directory(base, ent) && ent->d_name[0] != '.')
 
 static const char *shell_tests__dir(char *path, size_t size)
@@ -538,8 +538,9 @@ static const char *shell_tests__dir(char *path, size_t size)
 
 static int shell_tests__max_desc_width(void)
 {
-	DIR *dir;
+	struct dirent **entlist;
 	struct dirent *ent;
+	int n_dirs;
 	char path_dir[PATH_MAX];
 	const char *path = shell_tests__dir(path_dir, sizeof(path_dir));
 	int width = 0;
@@ -547,11 +548,11 @@ static int shell_tests__max_desc_width(void)
 	if (path == NULL)
 		return -1;
 
-	dir = opendir(path);
-	if (!dir)
+	n_dirs = scandir(path, &entlist, NULL, alphasort);
+	if (n_dirs == -1)
 		return -1;
 
-	for_each_shell_test(dir, path, ent) {
+	for_each_shell_test(entlist, n_dirs, path, ent) {
 		char bf[256];
 		const char *desc = shell_test__description(bf, sizeof(bf), path, ent->d_name);
 
@@ -563,7 +564,8 @@ static int shell_tests__max_desc_width(void)
 		}
 	}
 
-	closedir(dir);
+	free(entlist);
+
 	return width;
 }
 
@@ -589,8 +591,9 @@ static int shell_test__run(struct test *test, int subdir __maybe_unused)
 
 static int run_shell_tests(int argc, const char *argv[], int i, int width)
 {
-	DIR *dir;
+	struct dirent **entlist;
 	struct dirent *ent;
+	int n_dirs;
 	char path_dir[PATH_MAX];
 	struct shell_test st = {
 		.dir = shell_tests__dir(path_dir, sizeof(path_dir)),
@@ -599,14 +602,14 @@ static int run_shell_tests(int argc, const char *argv[], int i, int width)
 	if (st.dir == NULL)
 		return -1;
 
-	dir = opendir(st.dir);
-	if (!dir) {
+	n_dirs = scandir(st.dir, &entlist, NULL, alphasort);
+	if (n_dirs == -1) {
 		pr_err("failed to open shell test directory: %s\n",
 			st.dir);
 		return -1;
 	}
 
-	for_each_shell_test(dir, st.dir, ent) {
+	for_each_shell_test(entlist, n_dirs, st.dir, ent) {
 		int curr = i++;
 		char desc[256];
 		struct test test = {
@@ -623,7 +626,7 @@ static int run_shell_tests(int argc, const char *argv[], int i, int width)
 		test_and_print(&test, false, -1);
 	}
 
-	closedir(dir);
+	free(entlist);
 	return 0;
 }
 
@@ -722,19 +725,20 @@ static int __cmd_test(int argc, const char *argv[], struct intlist *skiplist)
 
 static int perf_test__list_shell(int argc, const char **argv, int i)
 {
-	DIR *dir;
+	struct dirent **entlist;
 	struct dirent *ent;
+	int n_dirs;
 	char path_dir[PATH_MAX];
 	const char *path = shell_tests__dir(path_dir, sizeof(path_dir));
 
 	if (path == NULL)
 		return -1;
 
-	dir = opendir(path);
-	if (!dir)
+	n_dirs = scandir(path, &entlist, NULL, alphasort);
+	if (n_dirs == -1)
 		return -1;
 
-	for_each_shell_test(dir, path, ent) {
+	for_each_shell_test(entlist, n_dirs, path, ent) {
 		int curr = i++;
 		char bf[256];
 		struct test t = {
@@ -747,7 +751,7 @@ static int perf_test__list_shell(int argc, const char **argv, int i)
 		pr_info("%2d: %s\n", i, t.desc);
 	}
 
-	closedir(dir);
+	free(entlist);
 	return 0;
 }