From patchwork Mon Mar 25 17:52:34 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Guenter Roeck X-Patchwork-Id: 13602629 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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 07FBEC54E58 for ; Mon, 25 Mar 2024 17:52:59 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 4D9B710EA11; Mon, 25 Mar 2024 17:52:58 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b="kSD6VY3b"; dkim-atps=neutral Received: from mail-pf1-f172.google.com (mail-pf1-f172.google.com [209.85.210.172]) by gabe.freedesktop.org (Postfix) with ESMTPS id 4BAAB10E2CA for ; Mon, 25 Mar 2024 17:52:56 +0000 (UTC) Received: by mail-pf1-f172.google.com with SMTP id d2e1a72fcca58-6ea9a605ca7so1081249b3a.0 for ; Mon, 25 Mar 2024 10:52:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1711389175; x=1711993975; darn=lists.freedesktop.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:sender:from:to:cc:subject:date:message-id:reply-to; bh=XNSADZIa55EnhS6o0yIL3ifpTu+GjUejKXDxEmLThHE=; b=kSD6VY3bVDSLyt0pwFTfRG5HEwJaIISQUCq1b9OUTE5Oj0BysQNrDaE8L3KZ2Mw4hV DEVCwYSKtPV9F4k7TkGFawIT9XvQhDpp2e/lp7Js7UJHP9loSffz0Sy6HgPlPeSspMlL ppLBFTSvlEvqt9E3tyzTvY9hVgkePphuP/uiX0lA01qAWmL7yuP+0YghApVOmbWFb0bH d+A7oLmzLvDRfDM617eS66wDr9MMFWuTLYon6w4X3k8CZfg2UlfOL2l1hOEej88J380S KrZoQhbU098+zrhR7a22K1cN1NmTdUGQA9WbuvJO+jYFsg7VdxtQd+EMplV0r+ciibdp k9GQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1711389175; x=1711993975; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:sender:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=XNSADZIa55EnhS6o0yIL3ifpTu+GjUejKXDxEmLThHE=; b=kVO8OiIBi7RZss8+sUURLyitv+KtIa0EcEffj3wskrwzqNz4xzRnCk4FvlvNJXfUEt 7uZ3owPVtxUggbkrzqT/HLsp1CjgDL35mcMIBHKJ16WBIPfvALPca+D3bhyMPbPSsqts MqX2HLX+TbwL6Wk5fshogXKVXipiF1D/FblFYsbP3pn+9xOgSbekf9HWgOyX2OJCgKI6 mGAuj10JEBi+Moe7NWrP6K3pufy8ZK9EsUjg1SWjDozgV+bW+Wr5gbKZ7IxGhCfozYtv C3EJyLYaLuU6H4BbndxP5TZ5GGYreerifs9FFtWdonobY9P13W7VnkaONGGLYHygNO29 ZgDQ== X-Forwarded-Encrypted: i=1; AJvYcCWefN5VBupBFlbufq01Lh6ePBnuBeUQ0FVrQjDDkUSQKfj82Ivlz40NU0fbYL/3XDXW/ewYRTflrshWjRE7jwt9Jo856lX0YKXAhdWnVkfM X-Gm-Message-State: AOJu0Yw9qKAHxqKCViPMVkHtmFIQFSBqlSYUBhA0mToFb8IIeIb0iaSY pWLisQKLXalLvg4b2mJ+JZmPQWb3dj2Q2XS4GPV9MNM/opRVsmbG X-Google-Smtp-Source: AGHT+IGIDWtPHdUbX+7LWIxScptU3Z3k9sozN35URR01B7XvfxcUzrh1Z1HYjZAKi2mO+Me8ITFPPw== X-Received: by 2002:a05:6a20:6a0e:b0:1a3:c4ba:a453 with SMTP id p14-20020a056a206a0e00b001a3c4baa453mr6509702pzk.7.1711389175417; Mon, 25 Mar 2024 10:52:55 -0700 (PDT) Received: from server.roeck-us.net ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id dr18-20020a056a020fd200b005cd835182c5sm5239787pgb.79.2024.03.25.10.52.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 Mar 2024 10:52:53 -0700 (PDT) From: Guenter Roeck To: linux-kselftest@vger.kernel.org Cc: David Airlie , Arnd Bergmann , =?utf-8?q?Ma=C3=ADra_Canal?= , Dan Carpenter , Kees Cook , Daniel Diaz , David Gow , Arthur Grillo , Brendan Higgins , Naresh Kamboju , Maarten Lankhorst , Andrew Morton , Maxime Ripard , =?utf-8?b?VmlsbGUgU3lyasOkbMOk?= , Daniel Vetter , Thomas Zimmermann , dri-devel@lists.freedesktop.org, kunit-dev@googlegroups.com, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, loongarch@lists.linux.dev, netdev@vger.kernel.org, Guenter Roeck Subject: [PATCH v2 00/14] Add support for suppressing warning backtraces Date: Mon, 25 Mar 2024 10:52:34 -0700 Message-Id: <20240325175248.1499046-1-linux@roeck-us.net> X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Some unit tests intentionally trigger warning backtraces by passing bad parameters to kernel API functions. Such unit tests typically check the return value from such calls, not the existence of the warning backtrace. Such intentionally generated warning backtraces are neither desirable nor useful for a number of reasons. - They can result in overlooked real problems. - A warning that suddenly starts to show up in unit tests needs to be investigated and has to be marked to be ignored, for example by adjusting filter scripts. Such filters are ad-hoc because there is no real standard format for warnings. On top of that, such filter scripts would require constant maintenance. One option to address problem would be to add messages such as "expected warning backtraces start / end here" to the kernel log. However, that would again require filter scripts, it might result in missing real problematic warning backtraces triggered while the test is running, and the irrelevant backtrace(s) would still clog the kernel log. Solve the problem by providing a means to identify and suppress specific warning backtraces while executing test code. Support suppressing multiple backtraces while at the same time limiting changes to generic code to the absolute minimum. Architecture specific changes are kept at minimum by retaining function names only if both CONFIG_DEBUG_BUGVERBOSE and CONFIG_KUNIT are enabled. The first patch of the series introduces the necessary infrastructure. The second patch introduces support for counting suppressed backtraces. This capability is used in patch three to implement unit tests. Patch four documents the new API. The next two patches add support for suppressing backtraces in drm_rect and dev_addr_lists unit tests. These patches are intended to serve as examples for the use of the functionality introduced with this series. The remaining patches implement the necessary changes for all architectures with GENERIC_BUG support. With CONFIG_KUNIT enabled, image size increase with this series applied is approximately 1%. The image size increase (and with it the functionality introduced by this series) can be avoided by disabling CONFIG_KUNIT_SUPPRESS_BACKTRACE. This series is based on the RFC patch and subsequent discussion at https://patchwork.kernel.org/project/linux-kselftest/patch/02546e59-1afe-4b08-ba81-d94f3b691c9a@moroto.mountain/ and offers a more comprehensive solution of the problem discussed there. Design note: Function pointers are only added to the __bug_table section if both CONFIG_KUNIT_SUPPRESS_BACKTRACE and CONFIG_DEBUG_BUGVERBOSE are enabled to avoid image size increases if CONFIG_KUNIT is disabled. There would be some benefits to adding those pointers all the time (reduced complexity, ability to display function names in BUG/WARNING messages). That change, if desired, can be made later. Checkpatch note: Remaining checkpatch errors and warnings were deliberately ignored. Some are triggered by matching coding style or by comments interpreted as code, others by assembler macros which are disliked by checkpatch. Suggestions for improvements are welcome. Changes since RFC: - Introduced CONFIG_KUNIT_SUPPRESS_BACKTRACE - Minor cleanups and bug fixes - Added support for all affected architectures - Added support for counting suppressed warnings - Added unit tests using those counters - Added patch to suppress warning backtraces in dev_addr_lists tests Changes since v1: - Rebased to v6.9-rc1 - Added Tested-by:, Acked-by:, and Reviewed-by: tags [I retained those tags since there have been no functional changes] - Introduced KUNIT_SUPPRESS_BACKTRACE configuration option, enabled by default.