Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755267AbZFAVtr (ORCPT ); Mon, 1 Jun 2009 17:49:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752172AbZFAVtk (ORCPT ); Mon, 1 Jun 2009 17:49:40 -0400 Received: from mx-out2.daemonmail.net ([216.104.160.39]:57763 "EHLO mx-out2.daemonmail.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751615AbZFAVtj (ORCPT ); Mon, 1 Jun 2009 17:49:39 -0400 From: "Michael S. Zick" Reply-To: lkml@morethan.org To: Jon Masters Subject: Re: fishy code in arch/x86/kernel/tsc.c:time_cpufreq_notifier() Date: Mon, 1 Jun 2009 16:49:36 -0500 User-Agent: KMail/1.9.9 Cc: Christoph Hellwig , Dave Jones , Ingo Molnar , linux-kernel@vger.kernel.org References: <20090601142104.GA15907@infradead.org> <20090601163914.GA6098@infradead.org> <1243889818.31439.28.camel@localhost.localdomain> In-Reply-To: <1243889818.31439.28.camel@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200906011649.38694.lkml@morethan.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1839 Lines: 55 On Mon June 1 2009, Jon Masters wrote: > On Mon, 2009-06-01 at 12:39 -0400, Christoph Hellwig wrote: > > On Mon, Jun 01, 2009 at 12:29:55PM -0400, Dave Jones wrote: > > > diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c > > > index d57de05..78c54ea 100644 > > > --- a/arch/x86/kernel/tsc.c > > > +++ b/arch/x86/kernel/tsc.c > > > @@ -631,17 +631,15 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val, > > > void *data) > > > { > > > struct cpufreq_freqs *freq = data; > > > - unsigned long *lpj, dummy; > > > + unsigned long *lpj; > > > > > > if (cpu_has(&cpu_data(freq->cpu), X86_FEATURE_CONSTANT_TSC)) > > > return 0; > > > > > > - lpj = &dummy; > > > - if (!(freq->flags & CPUFREQ_CONST_LOOPS)) > > > + lpj = &boot_cpu_data.loops_per_jiffy; > > > #ifdef CONFIG_SMP > > > + if (!(freq->flags & CPUFREQ_CONST_LOOPS)) > > > lpj = &cpu_data(freq->cpu).loops_per_jiffy; > > > -#else > > > - lpj = &boot_cpu_data.loops_per_jiffy; > > > #endif > > > > This makes the code look a lot more sane and should fix the potential > > issue. > > Tiny niggle that you wind up setting lpj (loops per jiffy) twice if > you're on SMP and have CPUFREQ_CONST_LOOPS. > At least it is consistent. ;) You set lpj twice if your not on SMP and have CPUFREG_CONST_LOOPS. Mike > Jon. > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/