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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_nulls.h | |
| parent | 1c97be677f72b3c338312aecd36d8fff20322f32 (diff) | |
| download | lwn-1658d35ead5d8dd76f2b2d6ad0e32c08d123faa2.tar.gz lwn-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_nulls.h')
| -rw-r--r-- | include/linux/list_nulls.h | 2 |
1 files changed, 1 insertions, 1 deletions
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, |