[PATCH RESEND v2 03/12] selftests/mm: mremap_test: simplify errno handling

[Sarthak Sharma]

mremap_move_multi_invalid_vmas() saves and restores
errno around several checks even when no other function
call can change it. Remove these instances and compare
errno directly.

Also move perror() after the userfaultfd skip check
to avoid printing an error when the test is skipped.

Suggested-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>
Signed-off-by: Sarthak Sharma <sarthak.sharma@xxxxxxx>
---
 tools/testing/selftests/mm/mremap_test.c | 19 ++++++-------------
 1 file changed, 6 insertions(+), 13 deletions(-)

diff --git a/tools/testing/selftests/mm/mremap_test.c b/tools/testing/selftests/mm/mremap_test.c
index ea1348a9532e..72e6e4c3bd87 100644
--- a/tools/testing/selftests/mm/mremap_test.c
+++ b/tools/testing/selftests/mm/mremap_test.c
@@ -727,7 +727,7 @@ static void mremap_move_multi_invalid_vmas(FILE *maps_fp,
 	const size_t size = 10 * page_size;
 	bool success = true;
 	char *ptr, *tgt_ptr;
-	int uffd, err, i;
+	int uffd, i;
 	void *res;
 	struct uffdio_api api = {
 		.api = UFFD_API,
@@ -736,12 +736,11 @@ static void mremap_move_multi_invalid_vmas(FILE *maps_fp,
 
 	uffd = syscall(__NR_userfaultfd, O_NONBLOCK);
 	if (uffd == -1) {
-		err = errno;
-		perror("userfaultfd");
-		if (err == EPERM) {
+		if (errno == EPERM) {
 			ksft_test_result_skip("%s - missing uffd", test_name);
 			return;
 		}
+		perror("userfaultfd");
 		success = false;
 		goto out;
 	}
@@ -810,14 +809,12 @@ static void mremap_move_multi_invalid_vmas(FILE *maps_fp,
 	 * time.
 	 */
 	res = mremap(ptr, size, size, MREMAP_MAYMOVE | MREMAP_FIXED, tgt_ptr);
-	err = errno;
 	if (res != MAP_FAILED) {
 		fprintf(stderr, "mremap() succeeded for multi VMA uffd armed\n");
 		success = false;
 		goto out_unmap;
 	}
-	if (err != EFAULT) {
-		errno = err;
+	if (errno != EFAULT) {
 		perror("mremap() unexpected error");
 		success = false;
 		goto out_unmap;
@@ -863,14 +860,12 @@ static void mremap_move_multi_invalid_vmas(FILE *maps_fp,
 	 * first VMA, but no others, and report a failure.
 	 */
 	res = mremap(ptr, size, size, MREMAP_MAYMOVE | MREMAP_FIXED, tgt_ptr);
-	err = errno;
 	if (res != MAP_FAILED) {
 		fprintf(stderr, "mremap() succeeded for multi VMA uffd armed\n");
 		success = false;
 		goto out_unmap;
 	}
-	if (err != EFAULT) {
-		errno = err;
+	if (errno != EFAULT) {
 		perror("mremap() unexpected error");
 		success = false;
 		goto out_unmap;
@@ -912,14 +907,12 @@ static void mremap_move_multi_invalid_vmas(FILE *maps_fp,
 	 * the last VMA, and report a failure.
 	 */
 	res = mremap(ptr, size, size, MREMAP_MAYMOVE | MREMAP_FIXED, tgt_ptr);
-	err = errno;
 	if (res != MAP_FAILED) {
 		fprintf(stderr, "mremap() succeeded for multi VMA uffd armed\n");
 		success = false;
 		goto out_unmap;
 	}
-	if (err != EFAULT) {
-		errno = err;
+	if (errno != EFAULT) {
 		perror("mremap() unexpected error");
 		success = false;
 		goto out_unmap;
-- 
2.53.0