From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932544AbcFUDAz (ORCPT ); Mon, 20 Jun 2016 23:00:55 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:2890 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754310AbcFUDAv (ORCPT ); Mon, 20 Jun 2016 23:00:51 -0400 X-IBM-Helo: d23dlp02.au.ibm.com X-IBM-MailFrom: xyjxie@linux.vnet.ibm.com X-IBM-RcptTo: linux-doc@vger.kernel.org;linux-kernel@vger.kernel.org;linux-pci@vger.kernel.org Subject: Re: [RESEND PATCH v2 2/4] PCI: Do not Use IORESOURCE_STARTALIGN to identify bridge resources To: Bjorn Helgaas References: <1464846411-16895-1-git-send-email-xyjxie@linux.vnet.ibm.com> <1464846411-16895-3-git-send-email-xyjxie@linux.vnet.ibm.com> <20160621015045.GB30307@localhost> Cc: nikunj@linux.vnet.ibm.com, zhong@linux.vnet.ibm.com, linux-doc@vger.kernel.org, aik@ozlabs.ru, linux-pci@vger.kernel.org, corbet@lwn.net, linux-kernel@vger.kernel.org, gwshan@linux.vnet.ibm.com, warrier@linux.vnet.ibm.com, alex.williamson@redhat.com, paulus@samba.org, bhelgaas@google.com, linuxppc-dev@lists.ozlabs.org From: Yongji Xie Date: Tue, 21 Jun 2016 10:59:51 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.1.1 MIME-Version: 1.0 In-Reply-To: <20160621015045.GB30307@localhost> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16062102-0052-0000-0000-000001A500EF X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16062102-0053-0000-0000-0000063ABE0C Message-Id: <522cb95b-349a-f34c-9930-9c3633b62419@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-06-21_01:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1604210000 definitions=main-1606210034 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2016/6/21 9:50, Bjorn Helgaas wrote: > On Thu, Jun 02, 2016 at 01:46:49PM +0800, Yongji Xie wrote: >> Now we use the IORESOURCE_STARTALIGN to identify bridge resources >> in __assign_resources_sorted(). That's quite fragile. We can't >> make sure that the PCI devices' resources will not use >> IORESOURCE_STARTALIGN any more. > Can you explain this a little more? I don't quite understand the > problem. Maybe you can give an example of the problem? Now there are two kinds of additional resources in the list: bridge resource and SR-IOV resource. Here we just want to fix the additional alignment for bridge. But if SR-IOV resource get the flag IORESOURCE_STARTALIGN which is not only for bridge, the current check seems to be wrong. And kernel parameter "resource_alignment" could set IORESOURCE_STARTALIGN for SR-IOV resource with my next patch applied. Thanks, Yongji >> In this patch, we try to use a more robust way to identify >> bridge resources. >> >> Signed-off-by: Yongji Xie >> --- >> drivers/pci/setup-bus.c | 9 ++++++--- >> 1 file changed, 6 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c >> index 55641a3..216ddbc 100644 >> --- a/drivers/pci/setup-bus.c >> +++ b/drivers/pci/setup-bus.c >> @@ -390,6 +390,7 @@ static void __assign_resources_sorted(struct list_head *head, >> struct pci_dev_resource *dev_res, *tmp_res, *dev_res2; >> unsigned long fail_type; >> resource_size_t add_align, align; >> + int index; >> >> /* Check if optional add_size is there */ >> if (!realloc_head || list_empty(realloc_head)) >> @@ -410,11 +411,13 @@ static void __assign_resources_sorted(struct list_head *head, >> >> /* >> * There are two kinds of additional resources in the list: >> - * 1. bridge resource -- IORESOURCE_STARTALIGN >> - * 2. SR-IOV resource -- IORESOURCE_SIZEALIGN >> + * 1. bridge resource >> + * 2. SR-IOV resource >> * Here just fix the additional alignment for bridge >> */ >> - if (!(dev_res->res->flags & IORESOURCE_STARTALIGN)) >> + index = dev_res->res - dev_res->dev->resource; >> + if (index < PCI_BRIDGE_RESOURCES || >> + index > PCI_BRIDGE_RESOURCE_END) > I think the code looks OK; at least, it seems to match the comment. > I'd just like to understand the problem a little better. > >> continue; >> >> add_align = get_res_add_align(realloc_head, dev_res->res); >> -- >> 1.7.9.5 >> > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev