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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 798D2C433DF for ; Tue, 25 Aug 2020 11:35:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5D4562068E for ; Tue, 25 Aug 2020 11:35:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729906AbgHYLfN (ORCPT ); Tue, 25 Aug 2020 07:35:13 -0400 Received: from mga12.intel.com ([192.55.52.136]:22554 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725893AbgHYLfJ (ORCPT ); Tue, 25 Aug 2020 07:35:09 -0400 IronPort-SDR: U5aAOU9Dlzwvyup0XJJS6/hkJ8i+AtdfBqCQ2NyWom1NSmw6v+uWD50zukLvLWdSPHh+yJdG0t LfydBSaOnerA== X-IronPort-AV: E=McAfee;i="6000,8403,9723"; a="135636757" X-IronPort-AV: E=Sophos;i="5.76,352,1592895600"; d="scan'208";a="135636757" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Aug 2020 04:35:08 -0700 IronPort-SDR: tQyRPfHqHTOmI/TbRlFigDMZSpBPcpM/C6j7QxHXoZ4cJoSe6mHkDnzJd8zNcgfpnOVdUUmbsk YPrSgcJ225aw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.76,352,1592895600"; d="scan'208";a="328839686" Received: from smile.fi.intel.com (HELO smile) ([10.237.68.40]) by orsmga008.jf.intel.com with ESMTP; 25 Aug 2020 04:35:02 -0700 Received: from andy by smile with local (Exim 4.94) (envelope-from ) id 1kAX3d-00BJMC-Pw; Tue, 25 Aug 2020 14:24:05 +0300 Date: Tue, 25 Aug 2020 14:24:05 +0300 From: Andy Shevchenko To: Valentin Schneider Cc: Ingo Molnar , Peter Zijlstra , Vincent Guittot , linux-kernel@vger.kernel.org, Dietmar Eggemann Subject: Re: [PATCH v1] sched/topology: Make compiler happy about unused constant definitions Message-ID: <20200825112405.GU1891694@smile.fi.intel.com> References: <20200824153902.57875-1-andriy.shevchenko@linux.intel.com> <20200825082636.GQ1891694@smile.fi.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 25, 2020 at 11:12:21AM +0100, Valentin Schneider wrote: > On 25/08/20 10:03, Valentin Schneider wrote: > > On 25/08/20 09:26, Andy Shevchenko wrote: > >> On Mon, Aug 24, 2020 at 06:09:41PM +0100, Valentin Schneider wrote: > >>> On 24/08/20 16:39, Andy Shevchenko wrote: > >>> > Compilation of almost each file ends up with > >>> > > >>> > In file included from .../include/linux/energy_model.h:10, > >>> > from .../include/linux/device.h:16, > >>> > from .../drivers/spi/spi.c:8: > >>> > .../include/linux/sched/topology.h:30:27: warning: ‘SD_DEGENERATE_GROUPS_MASK’ defined but not used [-Wunused-const-variable=] > >>> > 30 | static const unsigned int SD_DEGENERATE_GROUPS_MASK = > >>> > | ^~~~~~~~~~~~~~~~~~~~~~~~~ > >>> > ... > >>> > > >>> > Make compiler happy by annotating the static constants with __maybwe_unused. > > > Sorry, that's what I get for trying to be too succinct; what I tried to say > > was that SD_DEGENERATE_GROUPS_MASK should very much be used for SMP. If the > > build is !SMP, it shouldn't even be defined, IOW I'm perplexed as to where > > this is coming from. > > So I see how having this as a constvar rather than a constexpr is somewhat > daft (we get an instance per compilation unit), but none of my compilers > seem to complain (even with W=1). AFAIA the kernelbot didn't catch any of > it either. > > Out of curiosity, what's your compiler & compiler version? % gcc --version gcc (Debian 10.2.0-5) 10.2.0 % make O=... W=1 C=1 CF=-D__CHECK_ENDIAN__ -j64 > Alternatively we can make this a "proper" constant expression with the > below. It doesn't fix another static const in the same file, though that one requires DEBUG_SCHED to be enabled. Do you want me to split this fix and fix only the other case? > --- > > diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h > index 2d59ca77103e..b1331c4c48e9 100644 > --- a/include/linux/sched/topology.h > +++ b/include/linux/sched/topology.h > @@ -27,9 +27,11 @@ enum { > > /* Generate a mask of SD flags with the SDF_NEEDS_GROUPS metaflag */ > #define SD_FLAG(name, mflags) (name * !!((mflags) & SDF_NEEDS_GROUPS)) | > -static const unsigned int SD_DEGENERATE_GROUPS_MASK = > +enum { > + SD_DEGENERATE_GROUPS_MASK = > #include > -0; > +0 > +}; > #undef SD_FLAG > > #ifdef CONFIG_SCHED_DEBUG -- With Best Regards, Andy Shevchenko