Re: Problem with outstanding knotes and device detach - and a fix

[Taylor R Campbell]

Sorry, haven't had time yet to do a full review, but I spot at least
one problem that means this won't fly as is: kqueue_register and
kqueue_scan both call filter_touch under a spin lock, but with your
patch filter_touch now takes an rwlock -- which is forbidden under a
spin lock (and it'll crash under LOCKDEBUG).