From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933654AbcKPRLu (ORCPT ); Wed, 16 Nov 2016 12:11:50 -0500 Received: from mail-wm0-f68.google.com ([74.125.82.68]:34806 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752938AbcKPRLr (ORCPT ); Wed, 16 Nov 2016 12:11:47 -0500 Date: Wed, 16 Nov 2016 18:11:45 +0100 From: Johan Hovold To: Florian Fainelli Cc: Johan Hovold , Andrew Lunn , Vivien Didelot , "David S. Miller" , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] net: dsa: fix fixed-link-phy device leaks Message-ID: <20161116171145.GE4864@localhost> References: <1479307664-32428-1-git-send-email-johan@kernel.org> <42af57ed-df84-f628-659d-c982d30da7d5@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <42af57ed-df84-f628-659d-c982d30da7d5@gmail.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 16, 2016 at 09:06:26AM -0800, Florian Fainelli wrote: > On 11/16/2016 06:47 AM, Johan Hovold wrote: > > Make sure to drop the reference taken by of_phy_find_device() when > > registering and deregistering the fixed-link PHY-device. > > > > Note that we need to put both references held at deregistration. > > > > Fixes: 39b0c705195e ("net: dsa: Allow configuration of CPU & DSA port > > speeds/duplex") > > Signed-off-by: Johan Hovold > > --- > > > > Hi, > > > > This is one has been compile tested only, but fixes a couple of leaks > > similar to one that was found in the cpsw driver for which I just posted > > a patch. > > > > It turns out all drivers but DSA fail to deregister the fixed-link PHYs > > registered by of_phy_register_fixed_link(). Due to the way this > > interface was designed, deregistering such a PHY is a bit cumbersome and > > looks like it would benefit from a common helper. > > > > However, perhaps the interface should instead be changed so that the PHY > > device is returned so that drivers do not need to use > > of_phy_find_device() when they need to access properties of the fixed > > link (e.g. as in dsu_cpu_dsa_setup below). > > > > Thoughts? > > > > Thanks, > > Johan > > > > > > net/dsa/dsa.c | 8 +++++++- > > 1 file changed, 7 insertions(+), 1 deletion(-) > > > > diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c > > index a6902c1e2f28..798a6a776a5f 100644 > > --- a/net/dsa/dsa.c > > +++ b/net/dsa/dsa.c > > @@ -233,6 +233,8 @@ int dsa_cpu_dsa_setup(struct dsa_switch *ds, struct device *dev, > > genphy_read_status(phydev); > > if (ds->ops->adjust_link) > > ds->ops->adjust_link(ds, port, phydev); > > + > > + phy_device_free(phydev); /* of_phy_find_device */ > > } > > > > return 0; > > @@ -509,8 +511,12 @@ void dsa_cpu_dsa_destroy(struct device_node *port_dn) > > if (of_phy_is_fixed_link(port_dn)) { > > phydev = of_phy_find_device(port_dn); > > if (phydev) { > > - phy_device_free(phydev); > > fixed_phy_unregister(phydev); > > + /* Put references taken by of_phy_find_device() and > > + * of_phy_register_fixed_link(). > > + */ > > + phy_device_free(phydev); > > + phy_device_free(phydev); > > Double free, this looks bogus here. Actually would not this mean a > triple free since you already free in dsa_cpu_dsa_setup() which is > paired with dsa_cpu_dsa_destroy()? The naming of phy_device_free() is unfortunate when it's really a put(): void phy_device_free(struct phy_device *phydev) { put_device(&phydev->mdio.dev); } which may need to be called multiple times, specifically after a call to of_phy_find_device() which takes another reference. With this patch the refcounts are properly balanced. Johan