Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755544AbYARHcT (ORCPT ); Fri, 18 Jan 2008 02:32:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753013AbYARHcM (ORCPT ); Fri, 18 Jan 2008 02:32:12 -0500 Received: from fg-out-1718.google.com ([72.14.220.154]:8190 "EHLO fg-out-1718.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752220AbYARHcK (ORCPT ); Fri, 18 Jan 2008 02:32:10 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version:content-type:content-disposition:in-reply-to:user-agent; b=OSjZC9qxhuRSloxScDlltxfUYq4qPj2HO0dNz5CFx/4V8LTu9KRqKAL5b0bAE3DjEW/yGFf1B9qV0dwc/uYHFSy53odvfn4ANXp46b1nND+ezv+H9wqElmXargA7by5fvC4btW0NbEDyJc6x1VZtvLa+PZqyMAJtQLpud+ZEbts= Date: Fri, 18 Jan 2008 08:38:36 +0100 From: Jarek Poplawski To: Dave Young Cc: Kay Sievers , Alan Stern , Greg KH , stefanr@s5r6.in-berlin.de, David Brownell , Kernel development list Subject: Re: [PATCH 7/7] driver-core : convert semaphore to mutex in struct class Message-ID: <20080118073836.GA1703@ff.dom.local> References: <20080117194728.GA2598@ami.dom.local> <20080117203155.GA2791@ami.dom.local> <20080117232626.GC2905@ami.dom.local> <3ae72650801171755k85c4245i3b4c46a84ae8f52d@mail.gmail.com> <1200626323.5640.21.camel@lov.site> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2200 Lines: 55 On Fri, Jan 18, 2008 at 01:31:17PM +0800, Dave Young wrote: > On Jan 18, 2008 11:18 AM, Kay Sievers wrote: ... > > Yeah, might be better to wait until class_device is gone, otherwise you > > may need to fix stuff that is just going to be removed. Your change to > > have iterators for the class devices look like a nice preparation for > > future changes though. > > > > Our rough plan is: > > 2.6.25: > > - get the ~100 patches in Greg's tree (in -mm) merged :) > > 2.6.26: > > ??? - remove the 20 char limit in "struct device" > > - get rid of "struct class_device" > > Fine, thanks. > > Let's wait for other people's comment. Dave, I doubt you'll ever manage to do this if you're going to wait: probably there will be always some new changes like this around... IMHO, it would be nice to get the real state of current lockdep problems here to figure out if there is any chance to do this right & without any warnings with current lockdep. If I got it right from earlier threads it might be impossible with USB, at least. So, since I think these nesting levels seem to be wrong in 7/7 patch, maybe it's better to exclude it from this patchset, and to try this as testing for some time. My proposal is to do the annotations with mutex_lock_nested(), everywhere in this patch, according to 'real' relations between these classes from thread POV, so e.g.: mutex_lock_nested(&some_class->mutex, CLASS_PARENT); mutex_lock_nested(&some_class->mutex, CLASS_CLASS); ...or more if needed: mutex_lock_nested(&some_class->mutex, CLASS_CHILD); mutex_lock_nested(&some_class->mutex, CLASS_ROOT); ...etc. using adequate names for these enums, and only after this check what lockdep thinks about it. Then, if there are no obvious mistakes, but lockdep doesn't like it, send the patch and report without trying to 'silence' lockdep, so we could see what's going on, and if there are any chances to make it right. Thanks, Jarek P. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/