From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753001AbcFJT7a (ORCPT ); Fri, 10 Jun 2016 15:59:30 -0400 Received: from mail.savoirfairelinux.com ([208.88.110.44]:60159 "EHLO mail.savoirfairelinux.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750975AbcFJT71 (ORCPT ); Fri, 10 Jun 2016 15:59:27 -0400 From: Vivien Didelot To: Andrew Lunn Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@savoirfairelinux.com, "David S. Miller" , Florian Fainelli Subject: Re: [PATCH net-next 4/8] net: dsa: mv88e6xxx: do not increment bus refcount In-Reply-To: <20160609023641.GJ2227@lunn.ch> References: <20160609004456.5441-1-vivien.didelot@savoirfairelinux.com> <20160609004456.5441-5-vivien.didelot@savoirfairelinux.com> <20160609023641.GJ2227@lunn.ch> User-Agent: Notmuch/0.22 (http://notmuchmail.org) Emacs/24.5.1 (x86_64-unknown-linux-gnu) Date: Fri, 10 Jun 2016 15:59:22 -0400 Message-ID: <87k2hwq0h1.fsf@ketchup.mtl.sfl> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Andrew Lunn writes: > On Wed, Jun 08, 2016 at 08:44:52PM -0400, Vivien Didelot wrote: >> The MDIO device probe and remove functions are respectively incrementing >> and decrementing the bus refcount themselves. Since these bus level >> actions are out of the device scope, remove them. > > I agree with the patch. But have you checked the mdio layer is doing > the right thing? If not, we should fix that first. So I added some printing after incrementing/decrementing the refcount in get_device/put_device to track &ps->bus->dev, which name is "0.1". Regardless having this patch or not, the refcount of the 0.1 mii_bus device is 5 before loading the mv88e6xxx module on vf610-zii-dev-rev-b. Below is a portion of dmesg: [ 8.921647] get_device: 400d1000.etherne refcount: 4 [ 8.926225] get_device: 0.1 refcount: 2 [ 8.929561] get_device: mdio-mux refcount: 5 [ 8.934076] get_device: 0.1 refcount: 3 [ 8.937446] get_device: 0.1 refcount: 4 [ 8.940792] put_device: 0.1 refcount: 3 [ 8.944181] libphy: mdio_mux: probed [ 8.947885] mdio_bus 0.1:00: mdio_device_register [ 8.952649] get_device: 0.1:00 refcount: 2 [ 8.956283] get_device: 0.1 refcount: 4 [ 8.959838] get_device: 0.1:00 refcount: 3 [ 8.963991] get_device: 0.1:00 refcount: 4 [ 8.967598] put_device: 0.1:00 refcount: 3 [ 8.971298] get_device: 0.2 refcount: 2 [ 8.974687] get_device: mdio-mux refcount: 7 So it seems like of_ is managing the bus refcount on events such as a new child node (0.1:00). Thanks, Vivien