On Tue, Aug 15, 2017 at 10:13:36AM +0300, Leon Romanovsky wrote: > On Tue, Aug 15, 2017 at 02:33:05AM -0400, Zhu Yanjun wrote: > > The driver core clears the driver data to NULL after device_release > > or on probe failure. Thus, it is not necessary to manually clear the > > device driver data to NULL. > > > > It makes sense and I'm pretty sure that you are right, but I'm failing > to find the function in device core which sets it to NULL. Can you help > me and present the actual call stack to that code place?
http://elixir.free-electrons.com/linux/v4.13-rc1/source/drivers/base/dd.c#L840 The call to the remove callback is on line 833. This is done after dropping devres, so you could allocate the drv data inside a devm object and everything would unwind correctly. In this case, the kfree is explicit, so I would advocate for still putting the null near the kfree to minimize the time where a free'd pointer is present - eg incase a devm callback or some other bug accidently touches it. Jason
