Re: [patch 08/28] Input: prepare to sysfs integration

[Vojtech Pavlik]

On Thu, Oct 06, 2005 at 12:46:59PM -0500, Dmitry Torokhov wrote:
> On 10/5/05, Greg KH <gregkh@xxxxxxx> wrote:
> > On Wed, Oct 05, 2005 at 05:17:00PM -0500, Dmitry Torokhov wrote:
> >
> > > The reason is that I want to change input_allocate_device to take
> > > bitmap of supported events. This way I could allocate ABS tables
> > > dynamically at the same time I allocate input_dev itself and it will
> > > simplify error handling logic in drivers and it will save I think 1260
> > > bytes per input_dev structure which is nice. And I don't want to go
> > > through all subsystems yet again soI want to fold into my input
> > > dynalloc patch...
> >
> > That sounds good.
> >
> 
> Well, I tried implementing the proposal above and interface came out
> pretty awkward to use. My next option is to move abs table into
> "->private" structure, much like keytable was moved, or (for HID-like
> devices) allocate it when actually needed and adjust individual
> drivers. So I guess the patches that you have right now are good after
> all.
 
The problem is that the ->abs tables are accessed in the input core and
in the handlers, too, which means they have to share the lifetime rules
with the input_dev struct itself.

That means we probably have a problem with the drivers deallocating the
keytable, while the device still exists, because there is a reference to
it from say sysfs, and keyboard.c tries to access the keytable because
of an ioctl.

-- 
Vojtech Pavlik
SuSE Labs, SuSE CR
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