IP ID check (flush_id) in inet_gro_receive is necessary or not？

[Tan Xiaojun]

Hi everyone,

        I'm sorry to bother you. But I was confused.

        The IP ID check (flush_id) in inet_gro_receive is only used by 
tcp_gro_receive, and in tcp_gro_receive we have tcphdr check to ensure the 
order of skbs,
        like below:

        flush |= (__force int)(th->ack_seq ^ th2->ack_seq);
        flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);

        So if I remove the IP ID check in inet_gro_receive, there will be a 
problem ? And under what circumstances ?


Thanks.
Xiaojun.