From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5C64070838; Mon, 23 Jun 2025 21:09:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750712985; cv=none; b=B13aGLIAnuKGbP+wd9nFj9FZ+2/BMuBBm3DBezQTbFrT3n7WP81wU0rM90a6D+Flqzs1RHC/bWc+i87tbXaX4OotCsjhJNxXzZmpfRQdd+NI5gTORinndUI3WU4IPO2h6mISvEMA2ws6Hxm9yiKvR91zG2KvKPoVZmGrUlneg4A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750712985; c=relaxed/simple; bh=97XCfldlVipqjpx5BCOIvv6g0MXBSVHcrAuxBl3P+3w=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=WO2YaVKE7xc+4HJZiY0rrZUUdaynRtjbqf3DyA0sGEzxCqkJt/AszA8WDbOSyUhxje0lXYnD3vcnCFvF5oafXaexD7pNY12dFmPfROqm2H8hF+apFI/tpUpZgZZpb1rOSs30/M0C5rB34m28gsN5fs6ACPx+xIjT9O9rfeHDpwQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=C75M2QFd; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="C75M2QFd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DFEBDC4CEEA; Mon, 23 Jun 2025 21:09:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1750712985; bh=97XCfldlVipqjpx5BCOIvv6g0MXBSVHcrAuxBl3P+3w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=C75M2QFdilnJAMhs4iQjmuplhT5feBFoMOxZn8nUcXCrRTBu8JFc4+Q2rCK5LA4DD uCZHHVtNpgfISn+dvkno+LJ3Zd787n8v9hDLDUUZ3/ZofsB6evfMjsd1XP2hBZgQq7 lJPp8H4mYW5eiEWtVtGjGf8yANKF7VH0EtPfvPVE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Ian Rogers , Leo Yan , Adrian Hunter , James Clark , Kan Liang , Namhyung Kim , Arnaldo Carvalho de Melo , Sasha Levin Subject: [PATCH 5.15 099/411] perf tests switch-tracking: Fix timestamp comparison Date: Mon, 23 Jun 2025 15:04:03 +0200 Message-ID: <20250623130635.985156909@linuxfoundation.org> X-Mailer: git-send-email 2.50.0 In-Reply-To: <20250623130632.993849527@linuxfoundation.org> References: <20250623130632.993849527@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Leo Yan [ Upstream commit 628e124404b3db5e10e17228e680a2999018ab33 ] The test might fail on the Arm64 platform with the error: # perf test -vvv "Track with sched_switch" Missing sched_switch events # The issue is caused by incorrect handling of timestamp comparisons. The comparison result, a signed 64-bit value, was being directly cast to an int, leading to incorrect sorting for sched events. The case does not fail everytime, usually I can trigger the failure after run 20 ~ 30 times: # while true; do perf test "Track with sched_switch"; done 106: Track with sched_switch : Ok 106: Track with sched_switch : Ok 106: Track with sched_switch : Ok 106: Track with sched_switch : Ok 106: Track with sched_switch : Ok 106: Track with sched_switch : Ok 106: Track with sched_switch : Ok 106: Track with sched_switch : Ok 106: Track with sched_switch : Ok 106: Track with sched_switch : Ok 106: Track with sched_switch : Ok 106: Track with sched_switch : Ok 106: Track with sched_switch : Ok 106: Track with sched_switch : Ok 106: Track with sched_switch : FAILED! 106: Track with sched_switch : Ok 106: Track with sched_switch : Ok 106: Track with sched_switch : Ok 106: Track with sched_switch : Ok 106: Track with sched_switch : Ok 106: Track with sched_switch : Ok 106: Track with sched_switch : Ok 106: Track with sched_switch : Ok 106: Track with sched_switch : FAILED! 106: Track with sched_switch : Ok 106: Track with sched_switch : Ok I used cross compiler to build Perf tool on my host machine and tested on Debian / Juno board. Generally, I think this issue is not very specific to GCC versions. As both internal CI and my local env can reproduce the issue. My Host Build compiler: # aarch64-linux-gnu-gcc --version aarch64-linux-gnu-gcc (Ubuntu 13.3.0-6ubuntu2~24.04) 13.3.0 Juno Board: # lsb_release -a No LSB modules are available. Distributor ID: Debian Description: Debian GNU/Linux 12 (bookworm) Release: 12 Codename: bookworm Fix this by explicitly returning 0, 1, or -1 based on whether the result is zero, positive, or negative. Fixes: d44bc558297222d9 ("perf tests: Add a test for tracking with sched_switch") Reviewed-by: Ian Rogers Signed-off-by: Leo Yan Cc: Adrian Hunter Cc: James Clark Cc: Kan Liang Cc: Namhyung Kim Link: https://lore.kernel.org/r/20250331172759.115604-1-leo.yan@arm.com Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Sasha Levin --- tools/perf/tests/switch-tracking.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/perf/tests/switch-tracking.c b/tools/perf/tests/switch-tracking.c index 72abf5d86f712..e6a4efc20fd61 100644 --- a/tools/perf/tests/switch-tracking.c +++ b/tools/perf/tests/switch-tracking.c @@ -256,7 +256,7 @@ static int compar(const void *a, const void *b) const struct event_node *nodeb = b; s64 cmp = nodea->event_time - nodeb->event_time; - return cmp; + return cmp < 0 ? -1 : (cmp > 0 ? 1 : 0); } static int process_events(struct evlist *evlist, -- 2.39.5