From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 15 Jul 2003 16:51:16 -0700 From: Matt Porter To: Eugene Surovegin Cc: Matt Porter , linuxppc-embedded@lists.linuxppc.org Subject: Re: [RFC] consistent_sync and non L1 cache line aligned buffers Message-ID: <20030715165116.B8616@home.com> References: <5.1.0.14.2.20030714210220.0308a070@mail.zultys.com> <5.1.0.14.2.20030714210220.0308a070@mail.zultys.com> <20030715091731.C6208@home.com> <5.1.0.14.2.20030715092123.02ef0d20@mail.ebshome.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <5.1.0.14.2.20030715092123.02ef0d20@mail.ebshome.net>; from ebs@ebshome.net on Tue, Jul 15, 2003 at 09:27:10AM -0700 Sender: owner-linuxppc-embedded@lists.linuxppc.org List-Id: On Tue, Jul 15, 2003 at 09:27:10AM -0700, Eugene Surovegin wrote: > > At 09:17 AM 7/15/2003, Matt Porter wrote: > >I'll agree that it's a better hack, but since the offending areas in > >the SCSI subsystem are easily located, it seems wiser to fix upstream. > > Matt, the problem is it wasn't that *easy* to locate this, at least for me :) > I'm not sure that this is the only place.. I didn't mean to trivialize the difficulty of finding this from the path of tracking the symptom to the source. :) I merely was pointing out that now that you know the source of the problem, it's not *too* difficult to look for buffers allocated on the stack by simple inspection of the SCSI code. I only jumped in on this because I felt a little guilty that when I noticed this sometime back I got distracted and never tried to send a patch to the maintainers. :-/ > >We still need someone with interest AND time to properly fix the > >consistent alloc from irq issue. :) All of the patches post to date > >are incomplete bandaids. > > Uhh, I switched to solution which uses pre allocated consistent memory (10 > pages are enough for sym53c8xx_2). > It's still not a generic solution, but at least it's safe :) Are you doing this in the sym_2 driver or in the ppc consistent_* implementations? I only ask because I finally convinced myself recently that attempting to make all the locking safe in the VM subsystem was too much work. I think Paul suggested at one point that we might just preallocate a pool for atomic consistent allocations anyway. Regards, -- Matt Porter mporter@kernel.crashing.org ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/