the attached patch fixes one more race left in the new futex hashing code,
which triggers if a futex waiter gets a signal after it has been woken up
but before it actually wakes up.
Ingo
--- linux/kernel/futex.c.orig Sun Sep 29 11:42:35 2002
+++ linux/kernel/futex.c Sun Sep 29 11:48:16 2002
@@ -151,13 +151,13 @@
struct futex_q *q = container_of(vcache, struct futex_q, vcache);
struct list_head *head = hash_futex(new_page, q->offset);
- BUG_ON(list_empty(&q->list));
-
spin_lock(&futex_lock);
- q->page = new_page;
- list_del_init(&q->list);
- list_add_tail(&q->list, head);
+ if (!list_empty(&q->list)) {
+ q->page = new_page;
+ list_del(&q->list);
+ list_add_tail(&q->list, head);
+ }
spin_unlock(&futex_lock);
}