From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2992481AbcBRXqN (ORCPT ); Thu, 18 Feb 2016 18:46:13 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:36766 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1947614AbcBRXqI (ORCPT ); Thu, 18 Feb 2016 18:46:08 -0500 Date: Thu, 18 Feb 2016 15:46:07 -0800 From: Greg KH To: Paul Bolle Cc: netdev@vger.kernel.org, Dmitry Vyukov , Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= , Martin Wilck , Jarkko Sakkinen , Tilman Schmidt , linux-kernel@vger.kernel.org, gigaset307x-common@lists.sourceforge.net Subject: Re: [PATCH 1/1] ser_gigaset: use container_of() instead of detour Message-ID: <20160218234607.GA4517@kroah.com> References: <1455827348-8574-1-git-send-email-pebolle@tiscali.nl> <1455827348-8574-2-git-send-email-pebolle@tiscali.nl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1455827348-8574-2-git-send-email-pebolle@tiscali.nl> 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 Thu, Feb 18, 2016 at 09:29:08PM +0100, Paul Bolle wrote: > The purpose of gigaset_device_release() is to kfree() the struct > ser_cardstate that contains our struct device. This is done via a bit of > a detour. First we make our struct device's driver_data point to the > container of our struct ser_cardstate (which is a struct cardstate). In > gigaset_device_release() we then retrieve that driver_data again. And > after that we finally kfree() the struct ser_cardstate that was saved in > the struct cardstate. > > All of this can be achieved much easier by using container_of() to get > from our struct device to its container, struct ser_cardstate. Do so. > > Note that at the time the detour was implemented commit b8b2c7d845d5 > ("base/platform: assert that dev_pm_domain callbacks are called > unconditionally") had just entered the tree. That commit disconnected > our platform_device and our platform_driver. These were reconnected > again in v4.5-rc2 through commit 25cad69f21f5 ("base/platform: Fix > platform drivers with no probe callback"). And one of the consequences > of that fix was that it broke the detour via driver_data. That's because > it made __device_release_driver() stop being a NOP for our struct device > and actually do stuff again. One of the things it now does, is setting > our driver_data to NULL. That, in turn, makes it impossible for > gigaset_device_release() to get to our struct cardstate. Which has the > net effect of leaking a struct ser_cardstate at every call of this > driver's tty close() operation. So using container_of() has the > additional benefit of actually working. > > Reported-by: Dmitry Vyukov > Tested-by: Dmitry Vyukov > Signed-off-by: Paul Bolle > --- > drivers/isdn/gigaset/ser-gigaset.c | 9 +-------- > 1 file changed, 1 insertion(+), 8 deletions(-) This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read Documentation/stable_kernel_rules.txt for how to do this properly.