On Thu, 2013-03-07 at 13:14 -0500, Sasha Levin wrote: > Okay, I'm even more confused now. > > The expression in question is: > > hlist_entry_safe(rcu_dereference_bh(hlist_first_rcu(head))) > > You're saying that "rcu_dereference_bh(hlist_first_rcu(head))" can change > between > the two evaluations we do. That would mean that 'head' has changed in > between, right? > > In that case, the list itself has changed - which means that RCU has changed > the > list underneath us. > > hlist_first_rcu() doesn't have any side-effects, it doesn't modify the list > whatsoever, > so the only thing that can change is 'head'. Why is it allowed to change if > the list > is protected by RCU?
Thats the point of RCU ;) Things can change under us. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
