From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753048AbdJTL1R (ORCPT ); Fri, 20 Oct 2017 07:27:17 -0400 Received: from cloudserver094114.home.net.pl ([79.96.170.134]:46913 "EHLO cloudserver094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753019AbdJTL1Q (ORCPT ); Fri, 20 Oct 2017 07:27:16 -0400 From: "Rafael J. Wysocki" To: Greg KH Cc: Jeffy Chen , linux-kernel@vger.kernel.org, briannorris@chromium.org, heiko@sntech.de, dmitry.torokhov@gmail.com, dianders@chromium.org, tfiga@chromium.org, broonie@kernel.org, seanpaul@chromium.org, thierry.reding@gmail.com Subject: Re: [PATCH v3] driver core: Move device_links_purge() after bus_remove_device() Date: Fri, 20 Oct 2017 13:17:35 +0200 Message-ID: <2944574.zGy8XCJarq@aspire.rjw.lan> In-Reply-To: <20171020062201.GA18761@kroah.com> References: <20171020012316.30154-1-jeffy.chen@rock-chips.com> <3413769.dlVTNxayVy@aspire.rjw.lan> <20171020062201.GA18761@kroah.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Friday, October 20, 2017 8:22:01 AM CEST Greg KH wrote: > On Fri, Oct 20, 2017 at 03:22:07AM +0200, Rafael J. Wysocki wrote: > > On Friday, October 20, 2017 3:23:16 AM CEST Jeffy Chen wrote: > > > The current ordering of code in device_del() triggers a WARN_ON() > > > in device_links_purge(), because of an unexpected link status. > > > > > > The device_links_unbind_consumers() call in device_release_driver() > > > has to take place before device_links_purge() for the status of all > > > links to be correct, so move the device_links_purge() call in > > > device_del() after the invocation of bus_remove_device() which calls > > > device_release_driver(). > > > > > > Signed-off-by: Jeffy Chen > > > Reviewed-by: Rafael J. Wysocki > > > > OK, thanks. > > > > Greg, will you take this? > > Yes I will. But I don't understand if this is a bugfix that needs to go > to all stable kernels to resolve a problem that has always been there, > or it is ok for 4.15-rc1, as it's just a "do things in the correct > order" type of change. > > Any hints? Technically the problem has always been there, but it is only visible if device links are used in a specific way and I'm not sure whether or not there is any code in the tree where that's the case. That said AFAICS it should be safe to add Fixes: 9ed9895370ae (driver core: Functional dependencies tracking support) to it and handle it accordingly. Thanks, Rafael