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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2015-09-20 17:03:16 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2015-11-23 10:37:35 -0800
commit1658d35ead5d8dd76f2b2d6ad0e32c08d123faa2 (patch)
treeb237b079d8c057cb77e54f7e21baec00196b448f /include/linux/list.h
parent1c97be677f72b3c338312aecd36d8fff20322f32 (diff)
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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 <dvyukov@google.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'include/linux/list.h')
-rw-r--r--include/linux/list.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/list.h b/include/linux/list.h
index d7e31fe398b3..06c2d887a918 100644
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -186,7 +186,7 @@ static inline int list_is_last(const struct list_head *list,
*/
static inline int list_empty(const struct list_head *head)
{
- return head->next == head;
+ return READ_ONCE(head->next) == head;
}
/**
@@ -608,7 +608,7 @@ static inline int hlist_unhashed(const struct hlist_node *h)
static inline int hlist_empty(const struct hlist_head *h)
{
- return !h->first;
+ return !READ_ONCE(h->first);
}
static inline void __hlist_del(struct hlist_node *n)