From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754130Ab1H2QWe (ORCPT ); Mon, 29 Aug 2011 12:22:34 -0400 Received: from mx1.redhat.com ([209.132.183.28]:15648 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753658Ab1H2QWb (ORCPT ); Mon, 29 Aug 2011 12:22:31 -0400 Date: Mon, 29 Aug 2011 19:23:05 +0300 From: "Michael S. Tsirkin" To: Jan Kiszka Cc: Jesse Barnes , Brian King , "James E.J. Bottomley" , "Hans J. Koch" , Greg Kroah-Hartman , "linux-pci@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-scsi@vger.kernel.org" , "kvm@vger.kernel.org" Subject: Re: Broken pci_block_user_cfg_access interface Message-ID: <20110829162303.GD7480@redhat.com> References: <20110829150552.GA6851@redhat.com> <4E5BB358.3060705@siemens.com> <20110829155835.GB7480@redhat.com> <4E5BBAEF.8020808@siemens.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4E5BBAEF.8020808@siemens.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 Mon, Aug 29, 2011 at 06:14:39PM +0200, Jan Kiszka wrote: > On 2011-08-29 17:58, Michael S. Tsirkin wrote: > > On Mon, Aug 29, 2011 at 05:42:16PM +0200, Jan Kiszka wrote: > >> I still don't get what prevents converting ipr to allow plain mutex > >> synchronization. My vision is: > >> - push reset-on-error of ipr into workqueue (or threaded IRQ?) > >> - require mutex synchronization for common config space access > > > > Meaning pci_user_ read/write config? > > And pci_dev_reset, yes. > > > > >> and the > >> full reset cycle > >> - only exception: INTx status/masking access > >> => use pci_lock + test for reset_in_progress, skip operation if > >> that is the case > >> > >> That would allow to drop the whole block_user_cfg infrastructure. > >> > >> Jan > > > > We still need to block userspace access while INTx does > > the status/masking access, right? > > Yes, pci_lock would do that for us. Well this means block_user_cfg is not going away, this is what it really is: pci_lock + a bit to lock out userspace. > We should consider making the related bits for INTx test & mask/unmask > generic PCI services so that no user (uio_pci_generic, kvm, vfio) needs > to worry about the locking details. > > Jan > > -- > Siemens AG, Corporate Technology, CT T DE IT 1 > Corporate Competence Center Embedded Linux