[patch 0/1] fix async usb removal

[Okash Khawaja]

Hi,

I have tested this patch with apollo and it correctly deactivates the
module when usb is asynchronously unplugged. On unplugging, the tty
becomes null so using it caused null pointer deref. When this happens
in the context of catch_up kthread, it leads to kernel lock up a little
while later.

Let me know if there is anything missing, and I'll fix it.

Thanks,
Okash