selftests: harness: Move teardown conditional into test metadata

To get rid of setjmp()/longjmp(), the teardown logic needs to be usable
from __bail(). To access the atomic teardown conditional from there,
move it into the test metadata.
This also allows the removal of "setup_completed".

Signed-off-by: Thomas Weißschuh <[email protected]>
Acked-by: Shuah Khan <[email protected]>
Link: https://lore.kernel.org/r/20250505-nolibc-kselftest-harness-v4-9-ee4dd5257135@linutronix.de
Signed-off-by: Thomas Weißschuh <[email protected]>

Author: t-8ch

tools/testing/selftests/kselftest_harness.h

@@ -411,9 +411,9 @@
 		pid_t child = 1; \
 		int status = 0; \
 		/* Makes sure there is only one teardown, even when child forks again. */ \
-		bool *teardown = mmap(NULL, sizeof(*teardown), \
+		_metadata->no_teardown = mmap(NULL, sizeof(*_metadata->no_teardown), \
 			PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0); \
-		*teardown = false; \
+		*_metadata->no_teardown = true; \
 		if (sizeof(*self) > 0) { \
 			if (fixture_name##_teardown_parent) { \
 				self = mmap(NULL, sizeof(*self), PROT_READ | PROT_WRITE, \
@@ -431,23 +431,24 @@
 				/* Let setup failure terminate early. */ \
 				if (_metadata->exit_code) \
 					_exit(0); \
-				_metadata->setup_completed = true; \
+				*_metadata->no_teardown = false; \
 				fixture_name##_##test_name(_metadata, self, variant->data); \
 			} else if (child < 0 || child != waitpid(child, &status, 0)) { \
 				ksft_print_msg("ERROR SPAWNING TEST GRANDCHILD\n"); \
 				_metadata->exit_code = KSFT_FAIL; \
 			} \
 		} \
 		if (child == 0) { \
-			if (_metadata->setup_completed && !fixture_name##_teardown_parent && \
-					!__atomic_test_and_set(teardown, __ATOMIC_RELAXED)) \
+			if (!fixture_name##_teardown_parent && \
+					!__atomic_test_and_set(_metadata->no_teardown, __ATOMIC_RELAXED)) \
 				fixture_name##_teardown(_metadata, self, variant->data); \
 			_exit(0); \
 		} \
-		if (_metadata->setup_completed && fixture_name##_teardown_parent && \
-				!__atomic_test_and_set(teardown, __ATOMIC_RELAXED)) \
+		if (fixture_name##_teardown_parent && \
+				!__atomic_test_and_set(_metadata->no_teardown, __ATOMIC_RELAXED)) \
 			fixture_name##_teardown(_metadata, self, variant->data); \
-		munmap(teardown, sizeof(*teardown)); \
+		munmap(_metadata->no_teardown, sizeof(*_metadata->no_teardown)); \
+		_metadata->no_teardown = NULL; \
 		if (self && fixture_name##_teardown_parent) \
 			munmap(self, sizeof(*self)); \
 		if (WIFEXITED(status)) { \
@@ -916,7 +917,7 @@ struct __test_metadata {
 	int trigger; /* extra handler after the evaluation */
 	int timeout;	/* seconds to wait for test timeout */
 	bool aborted;	/* stopped test due to failed ASSERT */
-	bool setup_completed; /* did setup finish? */
+	bool *no_teardown; /* fixture needs teardown */
 	jmp_buf env;	/* for exiting out of test early */
 	struct __test_results *results;
 	struct __test_metadata *prev, *next;
@@ -1195,7 +1196,7 @@ static void __run_test(struct __fixture_metadata *f,
 	t->exit_code = KSFT_PASS;
 	t->trigger = 0;
 	t->aborted = false;
-	t->setup_completed = false;
+	t->no_teardown = NULL;
 	memset(t->env, 0, sizeof(t->env));
 	memset(t->results->reason, 0, sizeof(t->results->reason));