From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752020AbcBCJQ2 (ORCPT ); Wed, 3 Feb 2016 04:16:28 -0500 Received: from mout.kundenserver.de ([212.227.17.24]:54694 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751522AbcBCJQW (ORCPT ); Wed, 3 Feb 2016 04:16:22 -0500 From: Arnd Bergmann To: linux-arm-kernel@lists.infradead.org Cc: Roman Volkov , Michael Turquette , Stephen Boyd , linux-kernel@vger.kernel.org, Tony Prisk , Andrzej Hajda , linux-clk@vger.kernel.org Subject: Re: [PATCH] clk: vt8500: don't return possibly uninitialized data Date: Wed, 03 Feb 2016 10:15:34 +0100 Message-ID: <1624352.DBIo65mLZO@wuerfel> User-Agent: KMail/4.11.5 (Linux/3.16.0-10-generic; KDE/4.11.5; x86_64; ; ) In-Reply-To: <20160203113626.4a3f4f8a@v1ron-s7> References: <4790407.6zgSQCdsSB@wuerfel> <2326140.nrZ9Ej2PSt@wuerfel> <20160203113626.4a3f4f8a@v1ron-s7> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Provags-ID: V03:K0:f4IN03bik8EmX3wkBBTA4L/lQBnvbE04KKv0OQZe6Kz3sp8zhsP h/auJVC6NqA4edOjggHhWwTkdC3JLU8YGgG0QBOYvioMbjJCNT2bpLvUvrqXtgnHEe3zDUw r/jRW4Ef5yllNVMueLN3rPqsT4URszfKEWNIcVen4N/CA6ftnaucNb+osJ/J6IYIsKpRcWn zcvcH8YEqslrhU0yoOqug== X-UI-Out-Filterresults: notjunk:1;V01:K0:kMRhLvKVxg8=:AjPjL4StGeS/r3295wbCQ4 4a1yEPk0Ob8eCv8iq30Jq0exxywJ+aC3F2PXgzGyjpWftAn3KyZqo4wGX9Tm+AKUKuv4E7j6R /5rUsr/d6CSJ/G3wEXgEQEfmSRfYQ2rZTIbSd1sAIh9cSph0kBM5/iIhrIj81CvxJ6FP8MMpb rNQeplEQFNavMAqlfswGGM6+xMgabv8Hw3FunsOTvZXjq9xyHurXUYI0ypZprcIcg40mUS4bO pg6pLKNmGhKNxRxIIe3xlDb34XzsFc2fCnQCWjwdKd34gchq6UsFooUqmHannUyJpkWtDAlGr sYhjHC93BTAUu/1FEODrdmNi3srtSWuRq7eQmq7ulSXfcx2hXZ/k/tfR1CnJU/REFL/YgMqiY dVQygvRrBFWOX3fnrfNbiIQFA2ZhoD23JWCubgaj89NUQt6cgfCyPNuq5ztuI3XCXZc+jjOXL rK7t/KvaTTNiYiKR0/FK4yFfPNCmGXNkfKelU2cQqDiDVeuWB394XwQr87BaHme5m/VwZ7Ho1 ER5V7RUge7DuTcMpMdCcqYiIgcYEfpOl5N0bgIwzkp2PVui9g/rjp7dZbLPkJ0y/71hr7X2Lx ps3654IXZqQR9OUU7vzx3HqWTo70PbLd/LHST1VR9OIPYqzK3Au5QBLOq5DKtrpa1GooA85I0 D0kZWySk4DSAeKRgLuLxRv9j+zEeWkOqQ+4TMHjtvu7NJ3wTrtIQk3nFT2eEcK4OCLHkZpBgq rYRivhX5jMmzieCF Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 03 February 2016 11:36:26 Roman Volkov wrote: > > Hi Arnd, > > Thanks for fixing this code! Did someone reproduce this bug, or this > is something theoretical, based on the code analysis? I just never > heard about the issue. I can look into the code on the weekends too, I > have WM8505\WM8650 machines to test. I only fixed it after analysing the gcc warnings I got after Andrzej Hajda's patch, and he also did it to fix the initial problem he found using coccinelle, so I don't think anyone has run into the problem on live hardware. As long as all drivers ask for clock rates that are valid, you won't see either problem. > Is it enough to run the regular kernel build for WM8650 to see the > warnings, or there are special options in the kernel to run the compiler > test? The warning is hidden if you build with -Os (CONFIG_CC_OPTIMIZE_FOR_SIZE), and it may not happen with all gcc versions. I was using gcc-5.2. Arnd