From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760922AbXK1Wjo (ORCPT ); Wed, 28 Nov 2007 17:39:44 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760485AbXK1Wje (ORCPT ); Wed, 28 Nov 2007 17:39:34 -0500 Received: from pentafluge.infradead.org ([213.146.154.40]:33137 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760233AbXK1Wjc (ORCPT ); Wed, 28 Nov 2007 17:39:32 -0500 Date: Wed, 28 Nov 2007 14:38:40 -0800 From: Greg KH To: Alan Stern Cc: Kay Sievers , Kernel development list , Jonathan Corbet , Randy Dunlap , Cornelia Huck Subject: Re: [PATCH] kobject: make sure kobj->ktype is set before kobject_init Message-ID: <20071128223840.GA28007@kroah.com> References: <20071128214502.GA3255@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Wed, Nov 28, 2007 at 05:00:57PM -0500, Alan Stern wrote: > On Wed, 28 Nov 2007, Greg KH wrote: > > > On Wed, Nov 28, 2007 at 03:42:00PM -0500, Alan Stern wrote: > > > This patch (as1020) adds a check to kobject_init() to insure that the > > > ktype field is not NULL. This is just for safety's sake; as far as I > > > know there are no remaining places where the field is left unset. But > > > ironically, kset_init() did fail to set it! The patch fixes that and > > > removes some redundant initialization in kset_createa(). > > > > > > The patch also fixes up elevator_init(), where ktype was set after > > > calling kobject_init() instead of before. > > > > No, it's safe to set ktype after kobject_init, it was just not safe to > > set the kset. As Kay pointed out, I just added a patch to my tree to > > resolve this issue, and I'll go back and update the documentation now. > > > > I do like the "check for a ktype" warning, I'll go add that to my local > > tree and see what breaks. Odds are, all the static kobjects will :( > > You have to be careful. The ktype check I wrote lives in > kobject_init() -- that's why I had to make elevator_init() assign the > ktype before calling kobject_init(). If you put the check into > kobject_add() instead then you won't end up checking objects that get > initialized but not added. > > Yes, nobody would deliberately use a kobject without adding it, but it > could happen as the result of an failure between the _init and _add > calls. No, people do deliberately do this. Right now, after a few cleanup patches in my tree, there are only two users who create kobjects but do not register them, struct cdev and the kobj_map stuff. The cdev code I'll work on cleaning up, there's just some historical usages there that I've never felt all that comfortable with, and the kobj_map code I'd like to convert to just use a list and a kref and not a kobject at all so that I stop getting emails about it over time :) thanks, greg k-h