selftests/harness: order TEST_F and XFAIL_ADD constructors

TEST_F() allocates and registers its struct __test_metadata via mmap()
inside its constructor, and only then assigns the
_##fixture_##test##_object pointer.

XFAIL_ADD() runs in a constructor too and reads
_##fixture_##test##_object to initialize xfail->test. If XFAIL_ADD runs
first, xfail->test can be NULL and the expected failure will be reported
as FAIL.

Use constructor priorities to ensure TEST_F registration runs before
XFAIL_ADD, without adding extra state or runtime lookups.

Fixes: 2709473c9386 ("selftests: kselftest_harness: support using xfail")
Signed-off-by: Sun Jian <sun.jian.kdev@gmail.com>
Link: https://patch.msgid.link/20260225111451.347923-1-sun.jian.kdev@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/tools/testing/selftests/kselftest_harness.h b/tools/testing/selftests/kselftest_harness.h
index 16a119a4656c7eabc2d00b585c6e546f45237b2b..4afaef01c22e970a63883654f84ce485ebad5720 100644 (file)
--- a/tools/testing/selftests/kselftest_harness.h
+++ b/tools/testing/selftests/kselftest_harness.h
@@ -76,6 +76,9 @@ static inline void __kselftest_memset_safe(void *s, int c, size_t n)
                memset(s, c, n);
 }
 
+#define KSELFTEST_PRIO_TEST_F  20000
+#define KSELFTEST_PRIO_XFAIL   20001
+
 #define TEST_TIMEOUT_DEFAULT 30
 
 /* Utilities exposed to the test definitions */
@@ -465,7 +468,7 @@ static inline void __kselftest_memset_safe(void *s, int c, size_t n)
                        fixture_name##_teardown(_metadata, self, variant); \
        } \
        static struct __test_metadata *_##fixture_name##_##test_name##_object; \
-       static void __attribute__((constructor)) \
+       static void __attribute__((constructor(KSELFTEST_PRIO_TEST_F))) \
                        _register_##fixture_name##_##test_name(void) \
        { \
                struct __test_metadata *object = mmap(NULL, sizeof(*object), \
@@ -880,7 +883,7 @@ struct __test_xfail {
                .fixture = &_##fixture_name##_fixture_object, \
                .variant = &_##fixture_name##_##variant_name##_object, \
        }; \
-       static void __attribute__((constructor)) \
+       static void __attribute__((constructor(KSELFTEST_PRIO_XFAIL))) \
                _register_##fixture_name##_##variant_name##_##test_name##_xfail(void) \
        { \
                _##fixture_name##_##variant_name##_##test_name##_xfail.test = \