selftests: harness: Detect illegal mixing of kselftest and harness functionality

Users may accidentally use the kselftest_test_result_*() functions in
their harness tests. If ksft_finished() is not used, the results
reported in this way are silently ignored.

Detect such false-positive cases and fail the test.

A more correct test would be to reject *any* usage of the ksft APIs but
that would force code churn on users.

Correct usages, which do use ksft_finished() will not trigger this
validation as the test will exit before it.

Reported-by: Yuwen Chen <ywen.chen@foxmail.com>
Link: https://lore.kernel.org/lkml/tencent_56D79AF3D23CEFAF882E83A2196EC1F12107@qq.com/
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Link: https://lore.kernel.org/r/20260302-kselftest-harness-v2-4-3143aa41d989@linutronix.de
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

diff --git a/tools/testing/selftests/kselftest_harness.h b/tools/testing/selftests/kselftest_harness.h
index 16a119a4656c7eabc2d00b585c6e546f45237b2b..53e9e3d259dc8777fd4ed44342b7025d9d80b2bc 100644 (file)
--- a/tools/testing/selftests/kselftest_harness.h
+++ b/tools/testing/selftests/kselftest_harness.h
@@ -1222,7 +1222,16 @@ static void __run_test(struct __fixture_metadata *f,
                t->exit_code = KSFT_FAIL;
        } else if (child == 0) {
                setpgrp();
+
+               /* Reset state inherited from the harness */
+               ksft_reset_state();
+
                t->fn(t, variant);
+
+               if (__test_passed(t) && (ksft_get_fail_cnt() || ksft_get_error_cnt())) {
+                       ksft_print_msg("Illegal usage of low-level ksft APIs in harness test\n");
+                       t->exit_code = KSFT_FAIL;
+               }
                _exit(t->exit_code);
        } else {
                t->pid = child;