linux-kernel - [PATCH] selftests/harness: Limit step counter reporting

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Date:   Tue, 14 Jul 2020 11:30:23 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Shuah Khan <shuah@...nel.org>
Cc:     Ralph Campbell <rcampbell@...dia.com>,
        Andy Lutomirski <luto@...capital.net>,
        Will Drewry <wad@...omium.org>,
        linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] selftests/harness: Limit step counter reporting

When the selftest "step" counter grew beyond 255, non-fatal warnings
were being emitted, which is noisy and pointless. There are selftests
with more than 255 steps (especially those in loops, etc). Instead,
just cap "steps" to 254 and do not report the saturation.

Reported-by: Ralph Campbell <rcampbell@...dia.com>
Tested-by: Ralph Campbell <rcampbell@...dia.com>
Fixes: 9847d24af95c ("selftests/harness: Refactor XFAIL into SKIP")
Signed-off-by: Kees Cook <keescook@...omium.org>
---
 tools/testing/selftests/kselftest_harness.h | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/kselftest_harness.h b/tools/testing/selftests/kselftest_harness.h
index 935029d4fb21..4f78e4805633 100644
--- a/tools/testing/selftests/kselftest_harness.h
+++ b/tools/testing/selftests/kselftest_harness.h
@@ -680,7 +680,8 @@
 			__bail(_assert, _metadata->no_print, _metadata->step))
 
 #define __INC_STEP(_metadata) \
-	if (_metadata->passed && _metadata->step < 255) \
+	/* Keep "step" below 255 (which is used for "SKIP" reporting). */	\
+	if (_metadata->passed && _metadata->step < 253) \
 		_metadata->step++;
 
 #define is_signed_type(var)       (!!(((__typeof__(var))(-1)) < (__typeof__(var))1))
@@ -976,12 +977,6 @@ void __run_test(struct __fixture_metadata *f,
 		t->passed = 0;
 	} else if (t->pid == 0) {
 		t->fn(t, variant);
-		/* Make sure step doesn't get lost in reporting */
-		if (t->step >= 255) {
-			ksft_print_msg("Too many test steps (%u)!?\n", t->step);
-			t->step = 254;
-		}
-		/* Use 255 for SKIP */
 		if (t->skip)
 			_exit(255);
 		/* Pass is exit 0 */
-- 
2.25.1


-- 
Kees Cook