Commit efd04f8a authored by Alan Huang's avatar Alan Huang Committed by Paul E. McKenney
Browse files

rcu: Use WRITE_ONCE() for assignments to ->next for rculist_nulls 



When the objects managed by rculist_nulls are allocated with
SLAB_TYPESAFE_BY_RCU, old readers may still hold references to an object
even though it is just now being added, which means the modification of
->next is visible to readers.  This patch therefore uses WRITE_ONCE()
for assignments to ->next.

Signed-off-by: default avatarAlan Huang <mmpgouride@gmail.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Reviewed-by: default avatarJoel Fernandes (Google) <joel@joelfernandes.org>
parent 3292ba02

include/linux/rculist_nulls.h

+2 −2
Original line number Diff line number Diff line
@@ -101,7 +101,7 @@ static inline void hlist_nulls_add_head_rcu(struct hlist_nulls_node *n, 
{

	struct hlist_nulls_node *first = h->first;



	n->next = first;

	WRITE_ONCE(n->next, first);

	WRITE_ONCE(n->pprev, &h->first);

	rcu_assign_pointer(hlist_nulls_first_rcu(h), n);

	if (!is_a_nulls(first))
@@ -137,7 +137,7 @@ static inline void hlist_nulls_add_tail_rcu(struct hlist_nulls_node *n, 
		last = i;



	if (last) {

		n->next = last->next;

		WRITE_ONCE(n->next, last->next);

		n->pprev = &last->next;

		rcu_assign_pointer(hlist_nulls_next_rcu(last), n);

	} else {