From: Neil Horman <nhorman@tuxdriver.com>
Date: Sat,  2 Feb 2013 13:51:16 -0500

I can't say Im a huge fan of returning -EBUSY in open/close, but I
like it better than busy waiting while the poll path completes.

Sorry Neil, this is a show stopper for me.

There is no reason why, just because of bad timing, a device open or
close that would normally succeed, should fail.  And this situation is
only being created because the mutual exclusion and context handling
is "hard", well that's too bad :-)