[PATCH] selftests/futex: Skip futex_waitv tests if ENOSYS

[Wake Liu <wakel@google.com>]

The futex_waitv() syscall was introduced in Linux 5.16. The existing
test in futex_wait_timeout.c will fail on kernels older than 5.16
due to the syscall not being implemented.

Modify the test_timeout() function to check if the error returned
is ENOSYS. If it is, skip the test and report it as such, rather than
failing. This ensures the selftests can be run on a wider range of
kernel versions without false negatives.

Signed-off-by: Wake Liu <wakel@google.com>
---
 .../selftests/futex/functional/futex_wait_timeout.c   | 11 ++++++++---
 .../testing/selftests/futex/functional/futex_waitv.c  |  8 ++++++++
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/futex/functional/futex_wait_timeout.c b/tools/testing/selftests/futex/functional/futex_wait_timeout.c
index d183f878360b..323cab339814 100644
--- a/tools/testing/selftests/futex/functional/futex_wait_timeout.c
+++ b/tools/testing/selftests/futex/functional/futex_wait_timeout.c
@@ -64,9 +64,14 @@ void *get_pi_lock(void *arg)
 static void test_timeout(int res, int *ret, char *test_name, int err)
 {
 	if (!res || errno != err) {
-		ksft_test_result_fail("%s returned %d\n", test_name,
-				      res < 0 ? errno : res);
-		*ret = RET_FAIL;
+		if (errno == ENOSYS) {
+			ksft_test_result_skip("%s: %s\n",
+					      test_name, strerror(errno));
+		} else {
+			ksft_test_result_fail("%s returned %d\n", test_name,
+					      res < 0 ? errno : res);
+			*ret = RET_FAIL;
+		}
 	} else {
 		ksft_test_result_pass("%s succeeds\n", test_name);
 	}
diff --git a/tools/testing/selftests/futex/functional/futex_waitv.c b/tools/testing/selftests/futex/functional/futex_waitv.c
index 034dbfef40cb..2a86fd3ea657 100644
--- a/tools/testing/selftests/futex/functional/futex_waitv.c
+++ b/tools/testing/selftests/futex/functional/futex_waitv.c
@@ -59,6 +59,14 @@ void *waiterfn(void *arg)
 
 int main(int argc, char *argv[])
 {
+	if (!ksft_min_kernel_version(5, 16)) {
+		ksft_print_header();
+		ksft_set_plan(0);
+		ksft_print_msg("%s: FUTEX_WAITV not implemented until 5.16\n",
+			       basename(argv[0]));
+		ksft_print_cnts();
+		return KSFT_SKIP;
+	}
 	pthread_t waiter;
 	int res, ret = RET_PASS;
 	struct timespec to;
-- 
2.50.1.703.g449372360f-goog