Why is there no kthread_wait() call in the kernel?

If I'm running in the kernel and want to know when a kthread has
actually ended what are my options?

While I'm asking, why are there no calls to destroy locks? I can
create locks but I can't destroy them? Why not? Even if destroying
a lock is as simple as zeroing it out, wouldn't a call to do this
be a good place to check for errors?

Anyway, thanks for any help.
-- 
Kevin P. Neal                                http://www.pobox.com/~kpn/

Seen on bottom of IBM part number 1887724:
DO NOT EXPOSE MOUSE PAD TO DIRECT SUNLIGHT FOR EXTENDED PERIODS OF TIME.