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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 27B78C433F5 for ; Sun, 9 Sep 2018 09:36:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9E27F2075B for ; Sun, 9 Sep 2018 09:36:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9E27F2075B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=alien8.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726687AbeIIOZZ (ORCPT ); Sun, 9 Sep 2018 10:25:25 -0400 Received: from mail.skyhub.de ([5.9.137.197]:34224 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726609AbeIIOZZ (ORCPT ); Sun, 9 Sep 2018 10:25:25 -0400 X-Virus-Scanned: Nedap ESD1 at mail.skyhub.de Received: from mail.skyhub.de ([127.0.0.1]) by localhost (blast.alien8.de [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id jhtsMu0bqj22; Sun, 9 Sep 2018 11:36:18 +0200 (CEST) Received: from zn.tnic (p200300EC2BDD0A00329C23FFFEA6A903.dip0.t-ipconnect.de [IPv6:2003:ec:2bdd:a00:329c:23ff:fea6:a903]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id A9D811EC01F6; Sun, 9 Sep 2018 11:36:18 +0200 (CEST) Date: Sun, 9 Sep 2018 11:36:11 +0200 From: Borislav Petkov To: Miguel Ojeda Cc: Ingo Molnar , Peter Zijlstra , linux-kernel@vger.kernel.org Subject: Re: [PATCH] kernel/sched/core.c: Avoid unused variable on non-SMP configs Message-ID: <20180909093611.GA4614@zn.tnic> References: <20180908190553.GA4573@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20180908190553.GA4573@gmail.com> User-Agent: Mutt/1.9.5 (2018-04-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Sep 08, 2018 at 09:05:53PM +0200, Miguel Ojeda wrote: > On non-SMP configs, when only one of CONFIG_{PARAVIRT,IRQ_TIME}_ACCOUNTING > is defined, we are declaring a variable (irq_delta or steal) which > is not used: > > kernel/sched/core.c: In function ‘update_rq_clock_task’: > kernel/sched/core.c:139:17: warning: unused variable ‘irq_delta’ [-Wunused-variable] > s64 steal = 0, irq_delta = 0; > > The reason is that CONFIG_SMP guards HAVE_SCHED_AVG_IRQ, which in turn > disables the code guarded by HAVE_SCHED_AVG_IRQ. > > Cc: Ingo Molnar > Cc: Peter Zijlstra > Signed-off-by: Miguel Ojeda > --- > kernel/sched/core.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 625bc9897f62..d662d1e11843 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -135,8 +135,11 @@ static void update_rq_clock_task(struct rq *rq, s64 delta) > * In theory, the compile should just see 0 here, and optimize out the call > * to sched_rt_avg_update. But I don't trust it... > */ > -#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING) > - s64 steal = 0, irq_delta = 0; > +#if defined(HAVE_SCHED_AVG_IRQ) || defined(CONFIG_IRQ_TIME_ACCOUNTING) > + s64 irq_delta = 0; > +#endif > +#if defined(HAVE_SCHED_AVG_IRQ) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING) > + s64 steal = 0; > #endif > #ifdef CONFIG_IRQ_TIME_ACCOUNTING > irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time; > -- Alternatively, if you don't want to let the crazy ifdeffery in that function grow even more, you can simply do: --- diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 625bc9897f62..1728743360d4 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -136,7 +136,7 @@ static void update_rq_clock_task(struct rq *rq, s64 delta) * to sched_rt_avg_update. But I don't trust it... */ #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING) - s64 steal = 0, irq_delta = 0; + s64 steal __maybe_unused = 0, irq_delta = 0; #endif #ifdef CONFIG_IRQ_TIME_ACCOUNTING irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time; -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.