On Tue, 2013-05-21 at 05:09 -0700, Paul E. McKenney wrote:
> >
> > -#define hlist_nulls_first_rcu(head) \
> > - (*((struct hlist_nulls_node __rcu __force **)&(head)->first))
> > +#define hlist_nulls_first_rcu(head) \
> > + (*((struct hlist_nulls_node __rcu __force **) \
> > + &((volatile typeof(*head) *)head)->first))
>
> Why not use ACCESS_ONCE() or (better) rcu_dereference_raw() here?
More exactly we have :
#define list_entry_rcu(ptr, type, member) \
({typeof (*ptr) __rcu *__ptr = (typeof (*ptr) __rcu __force *)ptr; \
container_of((typeof(ptr))rcu_dereference_raw(__ptr), type, member); \
})
#define list_for_each_entry_rcu(pos, head, member) \
for (pos = list_entry_rcu((head)->next, typeof(*pos), member); \
&pos->member != (head); \
pos = list_entry_rcu(pos->member.next, typeof(*pos), member))
<< and >>
#define hlist_nulls_for_each_entry_rcu(tpos, pos, head, member)
\
for (pos = rcu_dereference_raw(hlist_nulls_first_rcu(head));
\
(!is_a_nulls(pos)) &&
\
({ tpos = hlist_nulls_entry(pos, typeof(*tpos), member); 1; });
\
pos = rcu_dereference_raw(hlist_nulls_next_rcu(pos)))
We need to change hlist_nulls_for_each_entry_rcu() to use same construct,
so that the rcu_dereference_raw() is performed at the right place.
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