Currently, ipv6 stack does not do any TOS reflection. To make the
behavior consistent with v4 stack, this commit adds TOS reflection in
tcp_v6_reqsk_send_ack() and tcp_v6_send_reset(). We clear the lower
2-bit ECN value of the received TOS in compliance with RFC 3168 6.1.5
robustness principles.
Signed-off-by: NWei Wang <weiwan@google.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>