[PATCH] Add locking to mlx(4)

Continuing with the theme of locking older storage drivers, I have patches to 
add locking to mlx(4) and mark it MPSAFE.  The patches are from HEAD but 
should apply to 8 or 9.  If you test it on 8 or 9 please enable INVARIANTS for 
at least the initial testing.  Thanks.

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

-- 
John Baldwin