From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [PATCH]: Fix old SCSI adapter crashes with CD-ROM (take 2) Date: Tue, 8 May 2007 18:52:58 +0200 Message-ID: <20070508165258.GE4163@kernel.dk> References: <20070508171710.1ac730cd@the-village.bc.nu> <20070508161444.GA4163@kernel.dk> <1178642376.3737.36.camel@mulgrave.il.steeleye.com> <4640A972.3010108@cs.wisc.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from agminet01.oracle.com ([141.146.126.228]:36162 "EHLO agminet01.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966168AbXEHQz2 (ORCPT ); Tue, 8 May 2007 12:55:28 -0400 Content-Disposition: inline In-Reply-To: <4640A972.3010108@cs.wisc.edu> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Mike Christie Cc: James Bottomley , Alan Cox , linux-scsi@vger.kernel.org, akpm@osdl.org, linux-kernel@vger.kernel.org On Tue, May 08 2007, Mike Christie wrote: > James Bottomley wrote: > > On Tue, 2007-05-08 at 18:14 +0200, Jens Axboe wrote: > >> On Tue, May 08 2007, Alan Cox wrote: > >>> The CD-ROM layer doesn't bounce requests for old ISA controllers (and > >>> nor should it). However they get injected into the SCSI layer via > >>> sr_ioctl which also doesn't bounce them and SCSI then passes the buffer > >>> along to a device with unchecked_isa_dma set which either panics or > >>> truncates the buffer to 24bits. > >>> > >>> According to Jens the right long term fix is for the CD layer to route > >>> the requests differently but in the mean time this has been tested by a > >>> victim and verified to sort the problem out. For the other 99.9% of users > >>> it's a no-op and doesn't bounce data. > >>> > >>> Signed-off-by: Alan Cox > >> Signed-off-by: Jens Axboe > >> > >> Christoph passed me his patch to get rid of ->generic_packet() in the > >> cdrom layer, so the work is almost complete. This patch is fine as a > >> work-around until that gets merged, though. > > > > Actually, I think the new scsi request infrastructure should be doing > > the bouncing (rather than have it done in each problem path we > > discover). > > > > Mike Christie tells me we're missing bouncing by accident in the > > scsi_execute path (but not the scsi_execute_async path). He says this > > is the fix he proposed: > > > > http://marc.info/?l=linux-scsi&m=115981479822790&w=2 > > > > Hey Jens and James, one thing I forgot to mention is that I could not > remember if I needed an extra bio_get in there. I thought I did not > because the caller is not touching the bio after the bio_endio calls > like is done with the blk/bio_map_user path. But I did that patch so > long ago I do not remember now. If you don't touch it after bio_endio(), then you don't need to hold an extra reference to it. I'll add your patch. -- Jens Axboe