From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762970AbXKMWbN (ORCPT ); Tue, 13 Nov 2007 17:31:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757127AbXKMWa5 (ORCPT ); Tue, 13 Nov 2007 17:30:57 -0500 Received: from pentafluge.infradead.org ([213.146.154.40]:32796 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756935AbXKMWa4 (ORCPT ); Tue, 13 Nov 2007 17:30:56 -0500 Date: Tue, 13 Nov 2007 14:22:42 -0800 From: Greg KH To: Arnd Bergmann Cc: Linus Torvalds , dm-devel@redhat.com, linux-kernel@vger.kernel.org, Milan Broz , Guido Guenther , Kevin Corry , stable@kernel.org Subject: Re: [stable] [2.6.24 PATCH 02/25] dm io:ctl use constant struct size Message-ID: <20071113222242.GB6132@kroah.com> References: <20071012170509.GM24157@agk.fab.redhat.com> <200710130016.29937.arnd@arndb.de> <20071015012621.GD10006@agk.fab.redhat.com> <200710150934.09842.arnd@arndb.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200710150934.09842.arnd@arndb.de> User-Agent: Mutt/1.5.16 (2007-06-09) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 15, 2007 at 09:34:09AM +0200, Arnd Bergmann wrote: > On Monday 15 October 2007, Alasdair G Kergon wrote: > > The underlying ABI is not changing, I hope - the trailing padding in the > > struct should not affect the processing of the data by dm, and I see no > > reason to continue maintaining the fiction that the 32-bit and 64-bit > > ioctls are in some way incompatible with each other when they aren't > > AFAIK. > > It's a corner case of some sort, as DM uses ioctl numbers differently > from most subsystems by splitting to code from the size argument > during processing. Your change is certainly not an _incompatible_ > change to the ABI, but 32 bit binaries compiled against the new > headers will use different ioctl numbers from those built against > older headers. > > This may break other code that expects a specific number, even > if your handler does not care. The old compat code handles both > variants (no variable size arguments), but /usr/bin/strace may have > encoded only one set of numbers AFAICT. > > > And yes, a follow-up patch can clean up our use of the compatibility > > mechanism, going a little bit further than the patch you attached, I > > hope. > > Ok, sounds good. I don't think it's the kind of patch that should go > into stable backports though. Ok, I've not added this patch (2/25) to the queue at all. If this is incorrect, please let me know. thanks, greg k-h