int flow_extract(struct sk_buff *, u16 in_port, struct sw_flow_key *, bool *is_frag);
void flow_used(struct sw_flow *, struct sk_buff *);
+u64 flow_used_time(unsigned long flow_jiffies);
u32 flow_hash(const struct sw_flow_key *);
int flow_cmp(const struct tbl_node *, void *target);