Merge branch 'tcp-add-tos-reflection-feature'

Wei Wang says:

====================
tcp: add tos reflection feature

This patch series adds a new tcp feature to reflect TOS value received in
SYN, and send it out in SYN-ACK, and eventually set the TOS value of the
established socket with this reflected TOS value. This provides a way to
set the traffic class/QoS level for all traffic in the same connection
to be the same as the incoming SYN. It could be useful for datacenters
to provide equivalent QoS according to the incoming request.
This feature is guarded by /proc/sys/net/ipv4/tcp_reflect_tos, and is by
default turned off.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>