in particular, if an interrupt handler needs to acquire a spinlock,
curproc might be NULL.  we can't use a thread id to identify a spinlock owner
since we don't have interrupt threads.

-Chuck


> However, using curproc as the identifier for a simplelock is incorrect,
> as simplelocks are owned by CPUs, not by processes.  Processes own
> sleep locks implemented by lockmgr().
> 
> -- 
>         -- Jason R. Thorpe <thorpej@zembu.com>