Am 18.02.2016 um 21:29 schrieb Paul Bolle: > 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.
You're absolutely right. Very nice!
> 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 <[email protected]>
> Tested-by: Dmitry Vyukov <[email protected]>
> Signed-off-by: Paul Bolle <[email protected]>
Acked-by: Tilman Schmidt <[email protected]>
Thanks for cleaning up the mess I left behind.
Tilman
--
Tilman Schmidt E-Mail: [email protected]
Bonn, Germany
Nous, on a des fleurs et des bougies pour nous protéger.
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