diff options
| author | Paul E. McKenney | 2015-09-18 08:45:22 -0700 |
|---|---|---|
| committer | Paul E. McKenney | 2015-10-06 11:16:42 -0700 |
| commit | 7f5f873c6a0772970d5fee1f364231207051ecd8 (patch) | |
| tree | ca06a26b0a485a63cf42417a12dea443a0df103c /include/linux/list.h | |
| parent | e62e3f620ba8d437f4998441fc11cf3dc9d466d1 (diff) | |
rculist: Use WRITE_ONCE() when deleting from reader-visible list
The various RCU list-deletion macros (list_del_rcu(),
hlist_del_init_rcu(), hlist_del_rcu(), hlist_bl_del_init_rcu(),
hlist_bl_del_rcu(), hlist_nulls_del_init_rcu(), and hlist_nulls_del_rcu())
do plain stores into the ->next pointer of the preceding list elemment.
Unfortunately, the compiler is within its rights to (for example) use
byte-at-a-time writes to update the pointer, which would fatally confuse
concurrent readers. This patch therefore adds the needed WRITE_ONCE()
macros.
KernelThreadSanitizer (KTSAN) reported the __hlist_del() issue, which
is a problem when __hlist_del() is invoked by hlist_del_rcu().
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Diffstat (limited to 'include/linux/list.h')
| -rw-r--r-- | include/linux/list.h | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/include/linux/list.h b/include/linux/list.h index 3e3e64a61002..993395a2e55c 100644 --- a/include/linux/list.h +++ b/include/linux/list.h @@ -87,7 +87,7 @@ static inline void list_add_tail(struct list_head *new, struct list_head *head) static inline void __list_del(struct list_head * prev, struct list_head * next) { next->prev = prev; - prev->next = next; + WRITE_ONCE(prev->next, next); } /** @@ -615,7 +615,8 @@ static inline void __hlist_del(struct hlist_node *n) { struct hlist_node *next = n->next; struct hlist_node **pprev = n->pprev; - *pprev = next; + + WRITE_ONCE(*pprev, next); if (next) next->pprev = pprev; } |