Workqueue and kernel panic on device disconnect

[fschaefer.oss@googlemail.com (Frank Schäfer)]

Am 25.10.2011 23:29, schrieb Frank Sch?fer:
> Hi,
>
> I'm trying to use a workqueue in a usb driver for polling the states 
> of the device buttons.
> That works fine, but when I disconnect the device, the kernel 
> sometimes explodes.
> The machine turns off immediately, without saving a backtrace (I will 
> try to make a photo tomorrow)
>
> The code:
>
>
>
> static struct delayed_work poll_work;
>
> static const struct usb_device_id device_table[] = {
>     {USB_DEVICE(0x1234, 0x5678)},
>     {}
> };
>
> static void poll(struct work_struct *work)
> {
>     schedule_delayed_work(&poll_work,
>                   msecs_to_jiffies(100));
> }
>
> MODULE_DEVICE_TABLE(usb, device_table);
>
> static int test_probe(struct usb_interface *intf,
>               const struct usb_device_id *id)
> {
>     INIT_DELAYED_WORK(&poll_work, poll);
>     schedule_delayed_work(&poll_work,
>                   msecs_to_jiffies(100));
>     return 0;
> }
>
> static void test_disconnect(struct usb_interface *intf)
> {
>     cancel_delayed_work_sync(&poll_work);
> }
>
> static struct usb_driver test_driver = {
>     .name       = MODULE_NAME,
>     .id_table   = device_table,
>     .probe      = test_probe,
>     .disconnect = test_disconnect,
> };
>
> static int __init test_mod_init(void)
> {
>     return usb_register(&test_driver);
> }
>
> static void __exit test_mod_exit(void)
> {
>     usb_deregister(&test_driver);
> }
>
> module_init(test_mod_init);
> module_exit(test_mod_exit);
>
>
> What am I doing wrong ?
> Is there anything else I have to do in addition to calling 
> cancel_delayed_work_sync() in the disconnect fcn ?
>
> Thanks,
> Frank Schaefer
>

I've managed to make a photo of the backtrace:

http://imageshack.us/photo/my-images/823/img075gv.jpg

Could this be a kernel bug ?

Regards,
Frank