rcu_segcblist_get_seglen
len += rcu_segcblist_get_seglen(rsclp, i);
len = rcu_segcblist_get_seglen(rsclp, from);
rclp->len = rcu_segcblist_get_seglen(rsclp, RCU_DONE_TAIL);
rclp->len += rcu_segcblist_get_seglen(rsclp, i);
long rcu_segcblist_get_seglen(struct rcu_segcblist *rsclp, int seg);
pending = rcu_segcblist_get_seglen(&rdp->cblist, RCU_DONE_TAIL);