[PATCH v2] selftests/vm: fix errno handling in mrelease_test

[Adam Sindelar <adam@wowsignal.io>]

mrelease_test should return KSFT_SKIP when process_mrelease is not
defined, but due to a perror call consuming the errno, it returns
KSFT_FAIL.

This patch decides the exit code before calling perror.

Signed-off-by: Adam Sindelar <adam@wowsignal.io>
---
v1->v2: Fixed second instance in the same file

 tools/testing/selftests/vm/mrelease_test.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/vm/mrelease_test.c b/tools/testing/selftests/vm/mrelease_test.c
index 96671c2f7d48..e8b17258579b 100644
--- a/tools/testing/selftests/vm/mrelease_test.c
+++ b/tools/testing/selftests/vm/mrelease_test.c
@@ -100,8 +100,10 @@ int main(void)
 
 	/* Test a wrong pidfd */
 	if (!syscall(__NR_process_mrelease, -1, 0) || errno != EBADF) {
+		/* perror overwrites errno, so this line must be first */
+		res = (errno == ENOSYS ? KSFT_SKIP : KSFT_FAIL);
 		perror("process_mrelease with wrong pidfd");
-		exit(errno == ENOSYS ? KSFT_SKIP : KSFT_FAIL);
+		exit(res);
 	}
 
 	/* Start the test with 1MB child memory allocation */
@@ -156,8 +158,9 @@ int main(void)
 	run_negative_tests(pidfd);
 
 	if (kill(pid, SIGKILL)) {
+		res = (errno == ENOSYS ? KSFT_SKIP : KSFT_FAIL);
 		perror("kill");
-		exit(errno == ENOSYS ? KSFT_SKIP : KSFT_FAIL);
+		exit(res);
 	}
 
 	success = (syscall(__NR_process_mrelease, pidfd, 0) == 0);
-- 
2.35.1