net:rfs: adjust table size checking

Make sure root user does not try something stupid.

Also make sure mask field in struct rps_sock_flow_table
does not share a cache line with the potentially often dirtied
flow table.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Fixes: 567e4b79731c ("net: rfs: add hash collision detection")
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc include/linux/netdevice.h
Simple merge

diff --cc net/core/sysctl_net_core.c
Simple merge