Re: [PATCH v5 06/13] lockdep: Implement crossrelease feature

Byungchul Park
2017-03-02T02:53:24Z

On Wed, Mar 01, 2017 at 02:17:07PM +0900, Byungchul Park wrote:
> > > +void lock_commit_crosslock(struct lockdep_map *lock)
> > > +{
> > > + struct cross_lock *xlock;
> > > + unsigned long flags;
> > > +
> > > + if (!current->xhlocks)
> > > + return;
> > > +
> > > + if (unlikely(current->lockdep_recursion))
> > > + return;
> > > +
> > > + raw_local_irq_save(flags);
> > > + check_flags(flags);
> > > + current->lockdep_recursion = 1;
> > > +
> > > + if (unlikely(!debug_locks))
> > > + return;
> > > +
> > > + if (!graph_lock())
> > > + return;
> > > +
> > > + xlock = &((struct lockdep_map_cross *)lock)->xlock;
> > > + if (atomic_read(&xlock->ref) > 0 && !commit_xhlocks(xlock))
> >
> > You terminate with graph_lock() held.
>
> Oops. What did I do? I'll fix it.

I remembered it. It's no problem because it would terminate there, only
if _both_ 'xlock->ref > 0' and 'commit_xhlocks returns 0' are true.
Otherwise, it will unlock the lock safely.