Re: event devices not released

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

Hi Erik,

On Mon, Feb 11, 2008 at 01:47:41PM +0100, Erik Slagter wrote:
> Hi,
>
> I think I've found a bug :-/
>
> Symptoms: when I remove (unplug) a USB keyboard or mouse, the corresponding 
> event device seems to be closed but not released; when I plug the device 
> back in, it gets a new input device handle. This means that after several 
> suspend/resume cycles (in which it seems all usb devices are virtually 
> unplugged and replugged) the kernel is out of event devices and complains 
> likewise. My nice little program that catches specific keystrokes also 
> stops to get any interesting events from that moment on. After reboot 
> everything works again as expected.
>
> I've seen a similar bug report on linux-kernel but it wasn't followed up 
> on. Also this only mentioned problems through suspend cycles while I also 
> have the problem simply plugging in and out.
>
> Environment: linux kernel 2.6.24 vanilla on i386. The event files are held 
> open by one or more processes when the devices are unplugged. Unfortunatly 
> my program is not the only one that has them open, but hald and Xorg also 
> have some of the devices open, so I cannot prevent this situation. Upon 
> POLLERR | POLLHUP my app closes all event devices and rescans the 
> /dev/input directory, this should be enough imho? I don't know how the 
> other apps handle unplugging.
>

What happens if you kill HAL and X and leave only your application
running? Do event devices get released/reused in this case? Do you
see POLLERR or POLLHUP signals devlievered to your app?

-- 
Dmitry