sched_ext: Add option -l in selftest runner to list all available tests

The selftest runner currently allows selecting tests via the -t
option. This patch adds a new -l option that lists all available tests,
providing users with an overview of the tests they can choose from. This
enhancement is especially useful for scripting and automation purposes,
making it easier to discover and run tests.

Signed-off-by: Shizhao Chen <shichen@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

Author: Shizhao Chen

tools/testing/selftests/sched_ext/runner.c

@@ -22,11 +22,12 @@ const char help_fmt[] =
 "\n"
 "  -t TEST       Only run tests whose name includes this string\n"
 "  -s            Include print output for skipped tests\n"
+"  -l            List all available tests\n"
 "  -q            Don't print the test descriptions during run\n"
 "  -h            Display this help and exit\n";
 
 static volatile int exit_req;
-static bool quiet, print_skipped;
+static bool quiet, print_skipped, list;
 
 #define MAX_SCX_TESTS 2048
 
@@ -133,14 +134,17 @@ int main(int argc, char **argv)
 
 	libbpf_set_strict_mode(LIBBPF_STRICT_ALL);
 
-	while ((opt = getopt(argc, argv, "qst:h")) != -1) {
+	while ((opt = getopt(argc, argv, "qslt:h")) != -1) {
 		switch (opt) {
 		case 'q':
 			quiet = true;
 			break;
 		case 's':
 			print_skipped = true;
 			break;
+		case 'l':
+			list = true;
+			break;
 		case 't':
 			filter = optarg;
 			break;
@@ -154,6 +158,13 @@ int main(int argc, char **argv)
 		enum scx_test_status status;
 		struct scx_test *test = &__scx_tests[i];
 
+		if (list) {
+			printf("%s\n", test->name);
+			if (i == (__scx_num_tests - 1))
+				return 0;
+			continue;
+		}
+
 		if (filter && should_skip_test(test, filter)) {
 			/*
 			 * Printing the skipped tests and their preambles can