RCU dependency chain 2

 1 /* How about this? */
 2 int lookup2(int key)
 3 {
 4   struct foo *p;
 5   int data;
 6
 7   rcu_read_lock();
 8   p = rcu_dereference(gp);
 9   if (p != NULL && p->key == key)
10     data = p->data;
11   else
12     data = -1;
13   rcu_read_unlock();
14   return data;
15 }