From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932246AbZE3OAX (ORCPT ); Sat, 30 May 2009 10:00:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758308AbZE3OAK (ORCPT ); Sat, 30 May 2009 10:00:10 -0400 Received: from mail-bw0-f222.google.com ([209.85.218.222]:62463 "EHLO mail-bw0-f222.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751645AbZE3OAJ convert rfc822-to-8bit (ORCPT ); Sat, 30 May 2009 10:00:09 -0400 MIME-Version: 1.0 In-Reply-To: References: <1243551665-23596-4-git-send-email-ebiederm@xmission.com> <4A1FA777.3040200@kernel.org> <4A210DEF.2030203@kernel.org> From: Kay Sievers Date: Sat, 30 May 2009 15:59:55 +0200 Message-ID: Subject: Re: [PATCH 04/24] sysfs: Normalize removing sysfs directories. To: "Eric W. Biederman" Cc: Tejun Heo , Andrew Morton , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, Cornelia Huck , linux-fsdevel@vger.kernel.org, Greg KH , "Eric W. Biederman" Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, May 30, 2009 at 15:07, Eric W. Biederman wrote: > My take is simply that a correct user has to wait until no one else > can find the kobject before calling kobject_del.  At which point > races are impossible, and it doesn't matter if sysfs_mutex is held > across the entire operation. We have circular references between kobjects in some "advanced" users. We can not break the circle without calling _del() on one of the objects involved, but at that time all of the objects are still referenced by another object. Only a _del() will break the circle, and result in a release of the objects involved. Not sure how that would behave with this change? Thanks, Kay