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| author |   Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-09-20 17:03:16 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-11-23 10:37:35 -0800 |
| commit | 1658d35ead5d8dd76f2b2d6ad0e32c08d123faa2 (patch) | |
| tree | b237b079d8c057cb77e54f7e21baec00196b448f /include/linux/list.h | |
| parent | list: Use WRITE_ONCE() when adding to lists and hlists (diff) | |
| download | linux-dev-1658d35ead5d8dd76f2b2d6ad0e32c08d123faa2.tar.xz linux-dev-1658d35ead5d8dd76f2b2d6ad0e32c08d123faa2.zip | |
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.h | 4 |
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) |