[PATCH] selftests/harness: Prevent infinite loop due to Assert in FIXTURE_TEARDOWN

[Shengyu Li]

This patch addresses an issue in the selftests/harness where an assertion within FIXTURE_TEARDOWN could trigger an infinite loop. 
The problem arises because the teardown procedure is meant to execute once, 
but the presence of failing assertions (ASSERT_EQ(0, 1)) 
leads to repeated attempts to execute teardown due to the long jump mechanism used by the harness for handling assertions.

To resolve this, the patch ensures that the teardown process runs only once, regardless of assertion outcomes, 
preventing the infinite loop and allowing tests to fail.

A simple test demo, also this is related to the issue mentioned in this patch
https://patchwork.kernel.org/project/linux-kselftest/patch/e2ba3f8c-80e6-477d-9cea-1c9af820e0ed@xxxxxxxxxxxx/

#include "kselftest_harness.h"

FIXTURE(f)
{
	int fd;
};

FIXTURE_SETUP(f)
{
	self->fd = 0;
}

FIXTURE_TEARDOWN(f)
{
	TH_LOG("TEARDOWN");
	ASSERT_EQ(0, 1);
	self->fd = -1;
}

TEST_F(f, open_close)
{
	ASSERT_NE(self->fd, 1);
}

TEST_HARNESS_MAIN


Signed-off-by: Shengyu Li <shengyu.li.evgeny@xxxxxxxxx>
---
 tools/testing/selftests/kselftest_harness.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/kselftest_harness.h b/tools/testing/selftests/kselftest_harness.h
index 4fd735e48ee7..230d62884885 100644
--- a/tools/testing/selftests/kselftest_harness.h
+++ b/tools/testing/selftests/kselftest_harness.h
@@ -383,6 +383,7 @@
 		FIXTURE_DATA(fixture_name) self; \
 		pid_t child = 1; \
 		int status = 0; \
+		bool jmp = false; \
 		memset(&self, 0, sizeof(FIXTURE_DATA(fixture_name))); \
 		if (setjmp(_metadata->env) == 0) { \
 			/* Use the same _metadata. */ \
@@ -399,8 +400,10 @@
 				_metadata->exit_code = KSFT_FAIL; \
 			} \
 		} \
+		else \
+			jmp = true; \
 		if (child == 0) { \
-			if (_metadata->setup_completed && !_metadata->teardown_parent) \
+			if (_metadata->setup_completed && !_metadata->teardown_parent && !jmp) \
 				fixture_name##_teardown(_metadata, &self, variant->data); \
 			_exit(0); \
 		} \
-- 
2.25.1