extern int udp_sendpage(struct sock *sk, struct page *page, int offset,
size_t size, int flags);
extern int udp_queue_rcv_skb(struct sock * sk, struct sk_buff *skb);
extern int udp_sendpage(struct sock *sk, struct page *page, int offset,
size_t size, int flags);
extern int udp_queue_rcv_skb(struct sock * sk, struct sk_buff *skb);