bpf: use --cgroup in test_suite if supplied

If the user supplies a --cgroup value in the arguments when running
the test_suite go ahaead and run the self tests there. I use this
to test with multiple cgroup users.
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools/testing/selftests/bpf/test_sockmap.c

@@ -1345,9 +1345,9 @@ static int populate_progs(char *bpf_file)
 	return 0;
 }
 
-static int __test_suite(char *bpf_file)
+static int __test_suite(int cg_fd, char *bpf_file)
 {
-	int cg_fd, err;
+	int err, cleanup = cg_fd;
 
 	err = populate_progs(bpf_file);
 	if (err < 0) {
@@ -1355,6 +1355,7 @@ static int __test_suite(char *bpf_file)
 		return err;
 	}
 
+	if (cg_fd < 0) {
 		if (setup_cgroup_environment()) {
 			fprintf(stderr, "ERROR: cgroup env failed\n");
 			return -EINVAL;
@@ -1372,6 +1373,7 @@ static int __test_suite(char *bpf_file)
 			fprintf(stderr, "ERROR: failed to join cgroup\n");
 			return -EINVAL;
 		}
+	}
 
 	/* Tests basic commands and APIs with range of iov values */
 	txmsg_start = txmsg_end = 0;
@@ -1391,20 +1393,24 @@ static int __test_suite(char *bpf_file)
 
 out:
 	printf("Summary: %i PASSED %i FAILED\n", passed, failed);
+	if (cleanup < 0) {
 		cleanup_cgroup_environment();
 		close(cg_fd);
+	}
 	return err;
 }
 
-static int test_suite(void)
+static int test_suite(int cg_fd)
 {
 	int err;
 
-	err = __test_suite(BPF_SOCKMAP_FILENAME);
+	err = __test_suite(cg_fd, BPF_SOCKMAP_FILENAME);
 	if (err)
 		goto out;
-	err = __test_suite(BPF_SOCKHASH_FILENAME);
+	err = __test_suite(cg_fd, BPF_SOCKHASH_FILENAME);
 out:
+	if (cg_fd > -1)
+		close(cg_fd);
 	return err;
 }
 
@@ -1417,7 +1423,7 @@ int main(int argc, char **argv)
 	int test = PING_PONG;
 
 	if (argc < 2)
-		return test_suite();
+		return test_suite(-1);
 
 	while ((opt = getopt_long(argc, argv, ":dhvc:r:i:l:t:",
 				  long_options, &longindex)) != -1) {
@@ -1483,6 +1489,9 @@ int main(int argc, char **argv)
 		}
 	}
 
+	if (argc <= 3 && cg_fd)
+		return test_suite(cg_fd);
+
 	if (!cg_fd) {
 		fprintf(stderr, "%s requires cgroup option: --cgroup <path>\n",
 			argv[0]);