From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S268968AbUHUKcZ (ORCPT ); Sat, 21 Aug 2004 06:32:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S268966AbUHUKcZ (ORCPT ); Sat, 21 Aug 2004 06:32:25 -0400 Received: from ns.virtualhost.dk ([195.184.98.160]:53223 "EHLO virtualhost.dk") by vger.kernel.org with ESMTP id S268968AbUHUKcR (ORCPT ); Sat, 21 Aug 2004 06:32:17 -0400 Date: Sat, 21 Aug 2004 12:32:09 +0200 From: Jens Axboe To: Bartlomiej Zolnierkiewicz Cc: Linux Kernel Subject: Re: serialize access to ide device Message-ID: <20040821103208.GF6755@suse.de> References: <20040802131150.GR10496@suse.de> <200408191514.13022.bzolnier@elka.pw.edu.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200408191514.13022.bzolnier@elka.pw.edu.pl> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 19 2004, Bartlomiej Zolnierkiewicz wrote: > > 2.6 breaks really really easily if you have any traffic on a device and > > issue a hdparm (or similar) command to it. Things like set_using_dma() > > and ide_set_xfer_rate() just stomp all over the drive regardless of what > > it's doing right now. > > Yep, known problem. Something should be done about it, it's pretty critical imho. > > I hacked something up for the SUSE kernel to fix this _almost_, it still > > doesn't handle cases where you want to serialize across more than a > > single channel. Not a common case, but I think there is such hardware > > out there (which?). > > > > Clearly something needs to be done about this, it's extremely > > frustrating not to be able to reliably turn on dma on a drive at all. > > I'm just tossing this one out there to solve 99% of the case, I'd like > > some input from you on what you feel we should do. > > What about adding new kind of REQ_SPECIAL request and converting > set_using_dma(), set_xfer_rate(), ..., to be callback functions for this > request? > > This should be a lot cleaner and will cover 100% cases. That will still only serialize per-channel. But yes, a lot cleaner. -- Jens Axboe