• Xin Long's avatar
    net: add support for ipv4 big tcp · b1a78b9b
    Xin Long authored
    Similar to Eric's IPv6 BIG TCP, this patch is to enable IPv4 BIG TCP.
    
    Firstly, allow sk->sk_gso_max_size to be set to a value greater than
    GSO_LEGACY_MAX_SIZE by not trimming gso_max_size in sk_trim_gso_size()
    for IPv4 TCP sockets.
    
    Then on TX path, set IP header tot_len to 0 when skb->len > IP_MAX_MTU
    in __ip_local_out() to allow to send BIG TCP packets, and this implies
    that skb->len is the length of a IPv4 packet; On RX path, use skb->len
    as the length of the IPv4 packet when the IP header tot_len is 0 and
    skb->len > IP_MAX_MTU in ip_rcv_core(). As the API iph_set_totlen() and
    skb_ip_totlen() are used in __ip_local_out() and ip_rcv_core(), we only
    need to update these APIs.
    
    Also in GRO receive, add the check for ETH_P_IP/IPPROTO_TCP, and allows
    the merged packet size >= GRO_LEGACY_MAX_SIZE in skb_gro_receive(). In
    GRO complete, set IP header tot_len to 0 when the merged packet size
    greater than IP_MAX_MTU in iph_set_totlen() so that it can be processed
    on RX path.
    
    Note that by checking skb_is_gso_tcp() in API iph_totlen(), it makes
    this implementation safe to use iph->len == 0 indicates IPv4 BIG TCP
    packets.
    Signed-off-by: default avatarXin Long <lucien.xin@gmail.com>
    Reviewed-by: default avatarDavid Ahern <dsahern@kernel.org>
    Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
    Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
    b1a78b9b
ip_input.c 19.1 KB