On Tue Aug 17 2010 at 15:41:11 +0200, Juergen Hannken-Illjes wrote:
> > > vp->v_freelisthd = NULL;
> > > mutex_exit(&vnode_free_list_lock);
> > >
> > > - if (vp->v_usecount != 0) {
> > > - /*
> > > - * was referenced again before we got the interlock
> > > - * Don't return to freelist - the holder of the last
> > > - * reference will destroy it.
> > > - */
> > > - mutex_exit(&vp->v_interlock);
> > > - mutex_enter(&vnode_free_list_lock);
> > > - goto retry;
> > > - }
> > > + KASSERT(vp->v_usecount == 0);
> >
> > It's not obvious from your commit message what prevents it from gaining
> > a reference after the lock is dropped.
>
> The interlock is taken before the freelist lock is dropped and vnodes on
> the free lists should never appear on other lists.
Not even the name cache?
(I can't remember off the top of my head, but IIRC there's something
sneaky about it)
