list: Use WRITE_ONCE() when adding to lists and hlists
Code that does lockless emptiness testing of non-RCU lists is relying
on the list-addition code to write the list head's ->next pointer
atomically. This commit therefore adds WRITE_ONCE() to list-addition
pointer stores that could affect the head's ->next pointer.
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
diff --git a/lib/list_debug.c b/lib/list_debug.c
index c24c2f7..3859bf6 100644
--- a/lib/list_debug.c
+++ b/lib/list_debug.c
@@ -37,7 +37,7 @@
next->prev = new;
new->next = next;
new->prev = prev;
- prev->next = new;
+ WRITE_ONCE(prev->next, new);
}
EXPORT_SYMBOL(__list_add);