[PATCH] ppbus/ppc locking

Please test!  This is the last non-MPSAFE network driver at this point.  This 
patch adds locking for the ppbus(4)/ppc(4) devices and the various ppbus 
child devices (lpt, vpo, lpbb, ppi, pps).  The basic model is that a single 
mutex in the ppc(4) driver protects the ppc0 hardware and is shared with the 
various child drivers.  Two drivers now have detach methods that did not have 
them before (plip and ppi).  I've done some simple testing on my laptop (able 
to load the drivers and do some simple things w/o panic'ing or tripping 
assertions), but I am not really able to test the peripheral drivers fully.

http://www.FreeBSD.org/~jhb/patches/ppc_locking.patch

-- 
John Baldwin