From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757818Ab3K0VWa (ORCPT ); Wed, 27 Nov 2013 16:22:30 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:51780 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757198Ab3K0VW2 (ORCPT ); Wed, 27 Nov 2013 16:22:28 -0500 Date: Wed, 27 Nov 2013 13:22:27 -0800 From: Greg KH To: Khalid Aziz Cc: "Eric W. Biederman" , bhelgaas@google.com, cl91tp@gmail.com, tianyu.lan@intel.com, khlebnikov@openvz.org, gnomes@lxorguk.ukuu.org.uk, indou.takao@jp.fujitsu.com, jility09@gmail.com, f.otti@gmx.at, mjg59@srcf.ucam.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, stable@vger.kernel.org Subject: Re: [PATCH] PCI: Clear Bus Master bit only on kexec reboot Message-ID: <20131127212227.GA31237@kroah.com> References: <1385579908-24608-1-git-send-email-khalid.aziz@oracle.com> <87ob55my8z.fsf@xmission.com> <52964F2C.1020803@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <52964F2C.1020803@oracle.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 27, 2013 at 12:59:40PM -0700, Khalid Aziz wrote: > On 11/27/2013 12:38 PM, ebiederm@xmission.com wrote: > >Khalid Aziz writes: > > > >>Add a flag to tell the PCI subsystem that kernel is shutting down > >>in prepapration to kexec a kernel. Add code in PCI subsystem to use > >>this flag to clear Bus Master bit on PCI devices only in case of > >>kexec reboot. This fixes https://bugzilla.kernel.org/show_bug.cgi?id=63861 > >>and avoids any other issues caused by clearing Bus Master bit on PCI > >>devices in normal shutdown path. This patch is based on discussion at > >>http://marc.info/?l=linux-pci&m=138425645204355&w=2 > > > >Scratches head. > > > >Given that most devices already call pci_disable_device which clears the > >bus master bit how does this change anything meaningful? > > > >Is is the problem here that most drivers are lazy and have a noop > >shutdown method? > > Yes, that is exactly the problem. Then fix the drivers please. It's not as if you don't have access to the source for them all... greg k-h