From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755305Ab1EPWg3 (ORCPT ); Mon, 16 May 2011 18:36:29 -0400 Received: from e5.ny.us.ibm.com ([32.97.182.145]:50559 "EHLO e5.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751535Ab1EPWg1 (ORCPT ); Mon, 16 May 2011 18:36:27 -0400 Date: Mon, 16 May 2011 15:36:21 -0700 From: Ram Pai To: Yinghai Lu Cc: Jesse Barnes , Linus Torvalds , "linux-kernel@vger.kernel.org" , "linux-pci@vger.kernel.org" , Andrew Morton , Bjorn Helgaas Subject: Re: [PATCH -v2] pci: Check bridge resources after resource allocation. Message-ID: <20110516223621.GX8195@ram-laptop> Reply-To: Ram Pai References: <4DC9E415.5010402@kernel.org> <20110512180638.GA5012@ram-laptop> <20110512182229.GQ8195@ram-laptop> <20110512113726.123fd85b@jbarnes-desktop> <20110512123412.64e9b4cc@jbarnes-desktop> <4DCDD589.8010309@kernel.org> <20110516075926.GW8195@ram-laptop> <4DD18F4A.5030208@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4DD18F4A.5030208@kernel.org> 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 Mon, May 16, 2011 at 01:55:38PM -0700, Yinghai Lu wrote: > On 05/16/2011 12:59 AM, Ram Pai wrote: > > On Fri, May 13, 2011 at 06:06:17PM -0700, Yinghai Lu wrote: > >> On 05/12/2011 12:34 PM, Jesse Barnes wrote: > >>> On Thu, 12 May 2011 12:18:43 -0700 > >>> Linus Torvalds wrote: > >>> > >>>> On Thu, May 12, 2011 at 11:37 AM, Jesse Barnes wrote: > >>>>> > >>>>> Linus, I don't have anything else queued up, so you may as well take > >>>>> this one directly if you want it in 2.6.39. It's a regression fix, but > >>>>> resource changes always make me nervous. Alternately, I could put it > >>>>> into 2.6.40 instead, the backport to 2.6.39.x if it survives until > >>>>> 2.6.40-rc2 or so... > >>>> > >>>> Considering the trouble resource allocation always ends up being, I'd > >>>> almost prefer that "mark it for stable and put it in the 2.6.40 > >>>> queue". > >>>> > >>>> Afaik this problem hasn't actually hit any "normal" users, has it? So ... > >>> > >>> Sounds good, thanks. Yeah I don't think it's hit anyone but Yinghai > >>> (at least I don't know of any other reports). > >>> > >> > >> please check this one, it should be safe for 2.6.39 ? > > > >> size0 = calculate_iosize(size, min_size, size1, > >> resource_size(b_res), 4096); > >> - size1 = !add_size? size0: > >> + size1 = (!add_head || (add_head && !add_size)) ? size0 : > >> calculate_iosize(size, min_size+add_size, size1, > >> resource_size(b_res), 4096); > > > > This solves the problem you encountered. > > > > But, I think, it still does not fix the following scenario: > > > > adjust_resource() failing to allocate additional resource to a hotplug bridge > > that has no children. In this case ->flags of that 'struct resource' > > continues to be set even when no resource is allocated to that hot-plug bridge. > > > that case: requested_size will be 0, but add_size will not be zero. > > res->flags is not cleared in pbus_size_xx, so it will be put into head. > so it will go through first path. > ... > if (!resource_size(res) && add_size) { > res->end = res->start + add_size - 1; > if(pci_assign_resource(list->dev, idx)) > reset_resource(res); > } else if (add_size) { > adjust_resource(res, res->start, > resource_size(res) + add_size); > } > > and if it fails to get assign, the flags will get clear in reset_resource. > > so it should be ok. and testing in one my setup show those flags get clear correctly and does not emit any warning. Ack. You are right. Linus/Jesse: can we consider this patch for 2.6.39? It is the simplest fix to the problem. Reviewed-by: Ram Pai RP