Pull up following revision(s) (requested by bouyer in ticket #1028):
sys/kern/kern_turnstile.c: revision 1.25 via patch
PR kern/41923: assertion "cur != owner" failed
In the for(;;) loop of turnstile_block(), the lock owner can change while
cur's lock is released (cur's lock is also the tschain_t's mutex).
Remove the KASSERT about owner being invariant and try to deal with the
fact that the owner can change instead.
http://mail-index.netbsd.org/tech-kern/2009/08/24/msg005957.html
and followups.

(snj)