From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1948321AbcBRU3R (ORCPT ); Thu, 18 Feb 2016 15:29:17 -0500 Received: from lb2-smtp-cloud6.xs4all.net ([194.109.24.28]:35077 "EHLO lb2-smtp-cloud6.xs4all.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1946533AbcBRU3O (ORCPT ); Thu, 18 Feb 2016 15:29:14 -0500 From: Paul Bolle To: netdev@vger.kernel.org Cc: Dmitry Vyukov , =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= , Greg Kroah-Hartman , Martin Wilck , Jarkko Sakkinen , Tilman Schmidt , linux-kernel@vger.kernel.org, gigaset307x-common@lists.sourceforge.net Subject: [PATCH 1/1] ser_gigaset: use container_of() instead of detour Date: Thu, 18 Feb 2016 21:29:08 +0100 Message-Id: <1455827348-8574-2-git-send-email-pebolle@tiscali.nl> X-Mailer: git-send-email 2.4.3 In-Reply-To: <1455827348-8574-1-git-send-email-pebolle@tiscali.nl> References: <1455827348-8574-1-git-send-email-pebolle@tiscali.nl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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(-) diff --git a/drivers/isdn/gigaset/ser-gigaset.c b/drivers/isdn/gigaset/ser-gigaset.c index 2a506fe0c8a4..d1f8ab915b15 100644 --- a/drivers/isdn/gigaset/ser-gigaset.c +++ b/drivers/isdn/gigaset/ser-gigaset.c @@ -373,13 +373,7 @@ static void gigaset_freecshw(struct cardstate *cs) static void gigaset_device_release(struct device *dev) { - struct cardstate *cs = dev_get_drvdata(dev); - - if (!cs) - return; - dev_set_drvdata(dev, NULL); - kfree(cs->hw.ser); - cs->hw.ser = NULL; + kfree(container_of(dev, struct ser_cardstate, dev.dev)); } /* @@ -408,7 +402,6 @@ static int gigaset_initcshw(struct cardstate *cs) cs->hw.ser = NULL; return rc; } - dev_set_drvdata(&cs->hw.ser->dev.dev, cs); tasklet_init(&cs->write_tasklet, gigaset_modem_fill, (unsigned long) cs); -- 2.4.3