in the pcb at the td_lock offset, rather than in the struct thread at
the td_lock offset. And we were storing a pointer to the old thread
rather than to the mutex. Why this didn't always kill us, I'll never
know.
Fix an obsolete comment and update the prototype in the comments.
Also note what variables are in what registers since this function is
a little complex...
neel@ found this problem and proposed this fix. This cures a number
of different problem reports out there, and gets us booting octeon to
the login prompt...
Submitted by: neel@
Reviewed by: rrs@, gonzo@
98dfb6b77e