Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751581AbWJMR5w (ORCPT ); Fri, 13 Oct 2006 13:57:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751585AbWJMR5w (ORCPT ); Fri, 13 Oct 2006 13:57:52 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:56592 "HELO iolanthe.rowland.org") by vger.kernel.org with SMTP id S1751581AbWJMR5v (ORCPT ); Fri, 13 Oct 2006 13:57:51 -0400 Date: Fri, 13 Oct 2006 13:57:48 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Alan Cox cc: Matthew Wilcox , Adam Belay , Arjan van de Ven , Benjamin Herrenschmidt , Greg KH , , Linux-pm mailing list , Kernel development list Subject: Re: [linux-pm] Bug in PCI core In-Reply-To: <1160760867.25218.77.camel@localhost.localdomain> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1234 Lines: 28 On Fri, 13 Oct 2006, Alan Cox wrote: > Ar Gwe, 2006-10-13 am 10:49 -0600, ysgrifennodd Matthew Wilcox: > > No it didn't. It's undefined behaviour to perform *any* PCI config > > access to the device while it's doing a D-state transition. It may have > > I think you missed the earlier parts of the story - the kernel caches > the base config register state. > > > happened to work with the chips you tried it with, but more likely you > > never hit that window because X simply didn't try to do that. > > Which is why the kernel caches the register state. This all came up long > ago and the solution we currently have was the one chosen after > considerable debate and analysis about things like locking. We preserved > the historical reliable interface going back to the early Linux PCI > support and used by all the apps. Would it be okay for pci_block_user_cfg_access() to use its own cache, so it doesn't interfere with data previously cached by pci_save_state()? Alan Stern - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/