From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm@xmission.com (Eric W. Biederman) Subject: Re: [PATCH] sysfs: Don't allow the creation of symlinks we can't remove Date: Thu, 22 Jul 2010 03:05:04 -0700 Message-ID: References: <20100621150826.762ac9f2.akpm@linux-foundation.org> <20100621222938.GA20583@suse.de> <20100621231058.GA1066@suse.de> <20100622035631.GA3755@suse.de> <1279792459.12439.0.camel@jlt3.sipsolutions.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Greg KH , Andrew Morton , "Rafael J. Wysocki" , "Maciej W. Rozycki" , Kay Sievers , Greg KH , netdev To: Johannes Berg Return-path: Received: from out02.mta.xmission.com ([166.70.13.232]:43701 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753812Ab0GVKFI (ORCPT ); Thu, 22 Jul 2010 06:05:08 -0400 In-Reply-To: <1279792459.12439.0.camel@jlt3.sipsolutions.net> (Johannes Berg's message of "Thu\, 22 Jul 2010 11\:54\:19 +0200") Sender: netdev-owner@vger.kernel.org List-ID: Johannes Berg writes: > On Thu, 2010-07-08 at 09:31 -0700, Eric W. Biederman wrote: >> Recently my tagged sysfs support revealed a flaw in the device core >> that a few rare drivers are running into such that we don't always put >> network devices in a class subdirectory named net/. >> >> Since we are not creating the class directory the network devices wind >> up in a non-tagged directory, but the symlinks to the network devices >> from /sys/class/net are in a tagged directory. All of which works >> until we go to remove or rename the symlink. When we remove or rename >> a symlink we look in the namespace of the target of the symlink. >> Since the target of the symlink is in a non-tagged sysfs directory we >> don't have a namespace to look in, and we fail to remove the symlink. >> >> Detect this problem up front and simply don't create symlinks we won't >> be able to remove later. This prevents symlink leakage and fails in >> a much clearer and more understandable way. > > Eric, I was looking into sysfs netns support for wireless, and with this > patch applied I just get the warning and no network interfaces. The warning patch just makes things fail faster. Although I get some of the wireless interfaces for hwsim when I use this one. > Was there any patch that was supposed to fix hwsim? - If you have my patches that fix CONFIG_SYSFS_DEPRECATED, you should find everything works there. As for a proper fix I have just resent my one liner to drives/base/core.c I can't think of a better option right now. For hwsim it is arguable, but the behaviour of sysfs for the bluetooth bnep driver is very clearly a 3 year old regression, and the cause is exactly the same. Eric