From efd04f8a8b45b8b98704b5860e363bab239b8bae Mon Sep 17 00:00:00 2001 From: Alan Huang Date: Thu, 6 Jul 2023 10:28:48 +0000 Subject: [PATCH] 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: Alan Huang Signed-off-by: Paul E. McKenney Reviewed-by: Joel Fernandes (Google) --- include/linux/rculist_nulls.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/include/linux/rculist_nulls.h b/include/linux/rculist_nulls.h index ba4c00dd8005a..89186c499dd47 100644 --- a/include/linux/rculist_nulls.h +++ b/include/linux/rculist_nulls.h @@ -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 { -- 2.30.2