From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758750AbXGZE1K (ORCPT ); Thu, 26 Jul 2007 00:27:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750979AbXGZE04 (ORCPT ); Thu, 26 Jul 2007 00:26:56 -0400 Received: from smtp2.linux-foundation.org ([207.189.120.14]:49540 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750999AbXGZE0z (ORCPT ); Thu, 26 Jul 2007 00:26:55 -0400 Date: Wed, 25 Jul 2007 21:26:38 -0700 From: Andrew Morton To: "Dave Young" Cc: linux-kernel@vger.kernel.org, "Dave Jones" , cpufreq@www.linux.org.uk Subject: Re: [PATCH]gx-suspmod.c use boot_cpu_data instead of current_cpu_data Message-Id: <20070725212638.79bc3945.akpm@linux-foundation.org> In-Reply-To: References: <20070725141905.GA4567@darkstar.te-china.tietoenator.com> <20070724234045.2cec5525.akpm@linux-foundation.org> X-Mailer: Sylpheed 2.4.1 (GTK+ 2.8.17; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 26 Jul 2007 04:20:10 +0000 "Dave Young" wrote: > >On 7/25/07, Andrew Morton wrote: > > On Wed, 25 Jul 2007 14:19:05 +0000 Dave Young wrote: > > > > > Hi, > > > in preemptible kernel will report BUG: using smp_processor_id() in preemptible, so use boot_cpu_data instead of current_cpu_data. > > > > > > Signed-off-by: Dave Young > > > > > > --- > > > arch/i386/kernel/cpu/cpufreq/gx-suspmod.c | 4 ++-- > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > diff -pur linux/arch/i386/kernel/cpu/cpufreq/gx-suspmod.c linux.new/arch/i386/kernel/cpu/cpufreq/gx-suspmod.c > > > --- linux/arch/i386/kernel/cpu/cpufreq/gx-suspmod.c 2007-07-25 14:11:06.000000000 +0000 > > > +++ linux.new/arch/i386/kernel/cpu/cpufreq/gx-suspmod.c 2007-07-25 13:57:29.000000000 +0000 > > > @@ -181,8 +181,8 @@ static __init struct pci_dev *gx_detect_ > > > struct pci_dev *gx_pci = NULL; > > > > > > /* check if CPU is a MediaGX or a Geode. */ > > > - if ((current_cpu_data.x86_vendor != X86_VENDOR_NSC) && > > > - (current_cpu_data.x86_vendor != X86_VENDOR_CYRIX)) { > > > + if ((boot_cpu_data.x86_vendor != X86_VENDOR_NSC) && > > > + (boot_cpu_data.x86_vendor != X86_VENDOR_CYRIX)) { > > > dprintk("error: no MediaGX/Geode processor found!\n"); > > > return NULL; > > > } > > > > um, I suspect it really wants to get at the current CPU. But putting a > > preempt_disable() around just that code is meaningless: the current CPU > > could change immediately before or after the code block. It needs deeper > > fixing, methinks. > The only target is to get the cpu vendor, so boot_cpu_data is enough, > the drivers/mtd/nand/cs553x_nand.c has the same usage. I think there's some vague ambition in there to support non-identical CPUs. In which case reading from the local CPU would make more sense. (waves frantically at cpufreq developers). otoh, it'll take some work I suspect. It'll need to sort out the overall scope of "local cpu". At what point and for how long should this code pin itself on a cpu?