psm(4) & atkbdc(4) locking

[Vladimir Kondratyev]

Hi All

In order to implement evdev support in psm(4) driver I`m going to add 
mutexes to psm and atkbdc drivers and mark psm interrupt and cdev 
handlers MPSAFE.
Atkbd(4) is depending on Giant like before.

Locking of these drivers seems to be low-hanging fruit as spl() calls 
are still in place but it has not occurred.

Does someone know why it is not done yet? For reasons other than "Nobody 
took care of it"?
Any hidden traps?

Patches can be found here:
https://reviews.freebsd.org/D10263 (atkbdc, serialize hw registers 
access)
https://reviews.freebsd.org/D10264 (psm, serialize softc access, mark 
interrupt and cdev handlers MPSAFE)

-- 
WBR
Vladimir Kondratyev