From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758439Ab0ELXTW (ORCPT ); Wed, 12 May 2010 19:19:22 -0400 Received: from kroah.org ([198.145.64.141]:45642 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753270Ab0ELXTU (ORCPT ); Wed, 12 May 2010 19:19:20 -0400 Date: Wed, 12 May 2010 16:19:06 -0700 From: Greg KH To: Borislav Petkov Cc: Jiri Kosina , "Ostrovsky, Boris" , "Herrmann3, Andreas" , Greg KH , "linux-kernel@vger.kernel.org" , "stable@kernel.org" , Jiri Benc , Thomas Renninger , Ingo Molnar , "H. Peter Anvin" , Andrew Morton , Linus Torvalds , "stable-review@kernel.org" , Alan Cox Subject: Re: [stable] [113/197] x86, cacheinfo: Calculate L3 indices Message-ID: <20100512231906.GB3588@kroah.com> References: <20100422190917.467545308@kvm.kroah.org> <20100505180228.GC15804@aftab> <20100506081721.GA20616@aftab> <20100506141358.GB20994@aftab> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100506141358.GB20994@aftab> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 06, 2010 at 04:13:58PM +0200, Borislav Petkov wrote: > From: Jiri Kosina > Date: Thu, May 06, 2010 at 09:46:21AM -0400 > > > Well, we have > > > > #ifdef CONFIG_K8_NB > > static inline struct pci_dev *node_to_k8_nb_misc(int node) > > { > > return (node < num_k8_northbridges) ? k8_northbridges[node] : NULL; > > } > > #else > > static inline struct pci_dev *node_to_k8_nb_misc(int node) > > { > > return NULL; > > } > > #endif > > > > So it legitimately returns NULL in two cases: > > > > 1) if someone passes too large node > > 2) if CONFIG_K8_NB is unset > > > > 1) Either we assume that node will always be in the range (i.e. > > amd_get_nb_id() will never go crazy return anything bogus), and then we > > could just drop the test completely. Or we want to check for such the > > possibility, and then node_to_k8_nb_misc() is going to return NULL in such > > cases, and so we want to check for it. > > No, we want to check it since K8_NB has many users - not only L3. > > > 2) is now moot, as all three in-tree callers are now under proper ifdefs > > (CONFIG_CPU_SUP_AMD, which depends on CONFIG_K8_NB after your patch has > > been applied). So I believe we could remove it, right? > > I don't think I understand "remove it" here. Which "it" you're referring to? > > > Either way, current state seems inconsistent. So either we should add the > > return value check to amd_calc_l3_indices() as well, or remove all the > > NULL magic altogether, i.e. the (untested) patch below. > > > > What do you think? > > Take a look at > > http://git.kernel.org/?p=linux/kernel/git/x86/linux-2.6-tip.git;a=commitdiff;h=f2b20e41407fccfcfacf927ff91ec888832a37af > > This does > > + if (num_k8_northbridges == 0) > + return; > > in amd_check_l3_disable(). > > So if K8_NB has failed initializing for some reason, we never go near > the pci devs and the node_to_k8_nb_misc() calls since we effectively > disable the L3 functionality. > > Thus the NULL pointer checks you remove in the patch below are > superfluous, I agree, and I have already removed those in my tree along > with the other improvements/fixes I'm working on right now. So, was there ever a patch applied that fixed the bug that Jiri found in the stable kernels with this original patch that I could apply? thanks, greg k-h