How to prevent a mutex being _enter()ed from being _destroy()ed?

[Edgar Fuß <ef%math.uni-bonn.de@localhost>]

I know very little about locking so that's probably a stupid question, but:

Is there a general scheme/rule/proposal how to prevent a mutex that someone 
is trying to mutex_enter() from being teared down by someone else calling 
mutex_destroy() on it during that?

Specifically, I'm trying to understand what should prevent a thread from 
destroying a socket's lock (by sofree()/soput()) while unp_gc() is trying 
to acquire that lock.