udl hotunplug broken

[Dave Airlie]

Hey,

Not sure how long this has been broken, considering plugging it in was
broken, unplugging is much worse. Is there anything outside my tree
that might be fixing this?

Currently it appears if I unplug udl while userspace has the device
open, it's bad, I get the userspace fb leaked thing which isn't
surprising, but I do get a lot of backtracing and warns which differ
depending on which way the race happens between X and unload.

I'm going to see if I can find a fix, but I'm guessing it's a lot of
digging to figure this out.

Dave.