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

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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 <mmpgouride@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
This commit is contained in:
Alan Huang 2023-07-06 10:28:48 +00:00 committed by Paul E. McKenney
parent 3292ba0229
commit efd04f8a8b
1 changed files with 2 additions and 2 deletions
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4
include/linux/rculist_nulls.h
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@ -101,7 +101,7 @@ static inline void hlist_nulls_add_head_rcu(struct hlist_nulls_node *n,
{ {
struct hlist_nulls_node *first = h->first; struct hlist_nulls_node *first = h->first;
n->next = first; WRITE_ONCE(n->next, first);
WRITE_ONCE(n->pprev, &h->first); WRITE_ONCE(n->pprev, &h->first);
rcu_assign_pointer(hlist_nulls_first_rcu(h), n); rcu_assign_pointer(hlist_nulls_first_rcu(h), n);
if (!is_a_nulls(first)) if (!is_a_nulls(first))
@ -137,7 +137,7 @@ static inline void hlist_nulls_add_tail_rcu(struct hlist_nulls_node *n,
last = i; last = i;
if (last) { if (last) {
n->next = last->next; WRITE_ONCE(n->next, last->next);
n->pprev = &last->next; n->pprev = &last->next;
rcu_assign_pointer(hlist_nulls_next_rcu(last), n); rcu_assign_pointer(hlist_nulls_next_rcu(last), n);
} else { } else {