From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C0D73C433EF for ; Tue, 16 Nov 2021 19:04:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A987B61391 for ; Tue, 16 Nov 2021 19:04:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234686AbhKPTHs (ORCPT ); Tue, 16 Nov 2021 14:07:48 -0500 Received: from mail.kernel.org ([198.145.29.99]:51260 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239717AbhKPTHp (ORCPT ); Tue, 16 Nov 2021 14:07:45 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 7FF4463214; Tue, 16 Nov 2021 19:04:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1637089488; bh=pJvfaUrErvbkJy1Pyta/U5BnafakH527rjx1wndzuxg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=q98FMqmonLufgrG7lvxe0mymL+Vv3NadSX4MOfHfev7CijU+q5WmMgy9GgLvA6rBi EBOX9hekreiuSA0K2hzLUVqFIZfgghml1d5cRRrc2+tGr5GVuMHcoa5gxoOwleNBOo m5HeV3ONGuGXX2eTOqLdcyK1A1aX4mkensF6q4jFtZZnuTVTAAk81mm397n7N7681f ro9ujxYDa0HeTc4a8g46n0i6UM67fldvJwBUSv5+f9nrYG+dSjY6MUveXqYF/XQg1Y FZIE2tG6Qpd4EkJz3B/VHDYP64IdAMBBx+MznDTbWBldsS3FRxkHncld1mXvNh/XMx RxtVczJAmDSHw== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Marco Elver , "Paul E . McKenney" , Sasha Levin , kasan-dev@googlegroups.com Subject: [PATCH AUTOSEL 5.15 02/65] kcsan: test: Fix flaky test case Date: Tue, 16 Nov 2021 14:03:22 -0500 Message-Id: <20211116190443.2418144-2-sashal@kernel.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20211116190443.2418144-1-sashal@kernel.org> References: <20211116190443.2418144-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Marco Elver [ Upstream commit ade3a58b2d40555701143930ead3d44d0b52ca9e ] If CONFIG_KCSAN_REPORT_VALUE_CHANGE_ONLY=n, then we may also see data races between the writers only. If we get unlucky and never capture a read-write data race, but only the write-write data races, then the test_no_value_change* test cases may incorrectly fail. The second problem is that the initial value needs to be reset, as otherwise we might actually observe a value change at the start. Fix it by also looking for the write-write data races, and resetting the value to what will be written. Signed-off-by: Marco Elver Signed-off-by: Paul E. McKenney Signed-off-by: Sasha Levin --- kernel/kcsan/kcsan_test.c | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-) diff --git a/kernel/kcsan/kcsan_test.c b/kernel/kcsan/kcsan_test.c index dc55fd5a36fcc..ada4a7a403b8d 100644 --- a/kernel/kcsan/kcsan_test.c +++ b/kernel/kcsan/kcsan_test.c @@ -488,17 +488,24 @@ static void test_concurrent_races(struct kunit *test) __no_kcsan static void test_novalue_change(struct kunit *test) { - const struct expect_report expect = { + const struct expect_report expect_rw = { .access = { { test_kernel_write_nochange, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE }, { test_kernel_read, &test_var, sizeof(test_var), 0 }, }, }; + const struct expect_report expect_ww = { + .access = { + { test_kernel_write_nochange, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE }, + { test_kernel_write_nochange, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE }, + }, + }; bool match_expect = false; + test_kernel_write_nochange(); /* Reset value. */ begin_test_checks(test_kernel_write_nochange, test_kernel_read); do { - match_expect = report_matches(&expect); + match_expect = report_matches(&expect_rw) || report_matches(&expect_ww); } while (!end_test_checks(match_expect)); if (IS_ENABLED(CONFIG_KCSAN_REPORT_VALUE_CHANGE_ONLY)) KUNIT_EXPECT_FALSE(test, match_expect); @@ -513,17 +520,24 @@ static void test_novalue_change(struct kunit *test) __no_kcsan static void test_novalue_change_exception(struct kunit *test) { - const struct expect_report expect = { + const struct expect_report expect_rw = { .access = { { test_kernel_write_nochange_rcu, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE }, { test_kernel_read, &test_var, sizeof(test_var), 0 }, }, }; + const struct expect_report expect_ww = { + .access = { + { test_kernel_write_nochange_rcu, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE }, + { test_kernel_write_nochange_rcu, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE }, + }, + }; bool match_expect = false; + test_kernel_write_nochange_rcu(); /* Reset value. */ begin_test_checks(test_kernel_write_nochange_rcu, test_kernel_read); do { - match_expect = report_matches(&expect); + match_expect = report_matches(&expect_rw) || report_matches(&expect_ww); } while (!end_test_checks(match_expect)); KUNIT_EXPECT_TRUE(test, match_expect); } -- 2.33.0