[PATCH] selftests: prctl: skip anon VMA naming test when unsupported

[Eva Kurchatova]

PR_SET_VMA_ANON_NAME returns EINVAL on a kernel built without
CONFIG_ANON_VMA_NAME, and every case in the renaming test then fails on
a feature that is not there.

Probe once in the fixture setup with a throwaway mapping and skip when
the kernel answers EINVAL. Only that error means the feature is
missing; the test still checks that an invalid name is refused with
EINVAL later, on a kernel that has it.

Signed-off-by: Eva Kurchatova <eva.kurchatova@xxxxxxxxxxxxx>
---
 .../testing/selftests/prctl/set-anon-vma-name-test.c  | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/tools/testing/selftests/prctl/set-anon-vma-name-test.c b/tools/testing/selftests/prctl/set-anon-vma-name-test.c
index 5f9589534da8..2d49a5114497 100644
--- a/tools/testing/selftests/prctl/set-anon-vma-name-test.c
+++ b/tools/testing/selftests/prctl/set-anon-vma-name-test.c
@@ -80,6 +80,17 @@ FIXTURE(vma) {
 
 FIXTURE_SETUP(vma) {
 	char template[] = "./set-anon-vma-test-XXXXXX";
+	void *probe;
+	int res;
+
+	/* Naming anonymous VMAs needs CONFIG_ANON_VMA_NAME. */
+	probe = mmap(NULL, AREA_SIZE, PROT_READ | PROT_WRITE,
+					MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	ASSERT_NE(probe, MAP_FAILED);
+	res = rename_vma((unsigned long)probe, AREA_SIZE, GOOD_NAME);
+	munmap(probe, AREA_SIZE);
+	if (res == -EINVAL)
+		SKIP(return, "CONFIG_ANON_VMA_NAME is not enabled");
 
 	self->ptr_anon = mmap(NULL, AREA_SIZE, PROT_READ | PROT_WRITE,
 					MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
-- 
2.55.0