Merge branch 'tcp-synflood-perf'

Eric Dumazet says:

====================
tcp: final work on SYNFLOOD behavior

In the first patch, I remove the costly association of SYNACK+COOKIES
to a listener. I believe other parts of the stack should be ready.

The second patch removes a useless write into listener socket
in tcp_rcv_state_process(), incurring false sharing in
tcp_conn_request()

Performance under SYNFLOOD goes from 3.2 Mpps to 6 Mpps.

Test was using a single TCP listener, on a host with 8 RX queues
on the NIC, and 24 cores (48 ht)
====================

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