tcp_rbtree_insert
void tcp_rbtree_insert(struct rb_root *root, struct sk_buff *skb);
tcp_rbtree_insert(root, skb);
tcp_rbtree_insert(&sk->tcp_rtx_queue, buff);
tcp_rbtree_insert(&sk->tcp_rtx_queue, nskb);
tcp_rbtree_insert(&sk->tcp_rtx_queue, syn_data);
tcp_rbtree_insert(&sk->tcp_rtx_queue, buff);
tcp_rbtree_insert(&sk->tcp_rtx_queue, skb);