From 1658d35ead5d8dd76f2b2d6ad0e32c08d123faa2 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sun, 20 Sep 2015 17:03:16 -0700 Subject: list: Use READ_ONCE() when testing for empty lists Most of the list-empty-check macros (list_empty(), hlist_empty(), hlist_bl_empty(), hlist_nulls_empty(), and hlist_nulls_empty()) use an unadorned load to check the list header. Given that these macros are sometimes invoked without the protection of a lock, this is not sufficient. This commit therefore adds READ_ONCE() calls to them. This commit does not touch llist_empty() because it already has the needed ACCESS_ONCE(). Reported-by: Dmitry Vyukov Signed-off-by: Paul E. McKenney --- include/linux/list_nulls.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/list_nulls.h') diff --git a/include/linux/list_nulls.h b/include/linux/list_nulls.h index 444d2b1313bd..b01fe1009084 100644 --- a/include/linux/list_nulls.h +++ b/include/linux/list_nulls.h @@ -57,7 +57,7 @@ static inline int hlist_nulls_unhashed(const struct hlist_nulls_node *h) static inline int hlist_nulls_empty(const struct hlist_nulls_head *h) { - return is_a_nulls(h->first); + return is_a_nulls(READ_ONCE(h->first)); } static inline void hlist_nulls_add_head(struct hlist_nulls_node *n, -- cgit v1.2.3-59-g8ed1b