[lkml]   [2018]   [Oct]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Patch in this message
Subject[PATCH AUTOSEL 4.4 04/65] ser_gigaset: use container_of() instead of detour
From: Paul Bolle <>

[ Upstream commit 8d2c3ab4445640957d136caa3629857d63544a2a ]

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 <>
Acked-by: Tilman Schmidt <>
Signed-off-by: David S. Miller <>
Signed-off-by: Sasha Levin <>
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 74bf1a17ae7c..b90776ef56ec 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,;

@@ -408,7 +402,6 @@ static int gigaset_initcshw(struct cardstate *cs)
cs->hw.ser = NULL;
return rc;
- dev_set_drvdata(&cs->hw.ser->, cs);

gigaset_modem_fill, (unsigned long) cs);
 \ /
  Last update: 2018-10-25 16:36    [W:0.196 / U:7.336 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site