Merge branch 'net-prefer-listeners-bound-to-an-address'

Peter Oskolkov says:

====================
net: prefer listeners bound to an address

A relatively common use case is to have several IPs configured
on a host, and have different listeners for each of them. We would
like to add a "catch all" listener on addr_any, to match incoming
connections not served by any of the listeners bound to a specific
address.

However, port-only lookups can match addr_any sockets when sockets
listening on specific addresses are present if so_reuseport flag
is set. This patchset eliminates lookups into port-only hashtable,
as lookups by (addr,port) tuple are easily available.

In a future patchset I plan to explore whether it is possible
to remove port-only hashtables completely: additional refactoring
will be required, as some non-lookup code uses the hashtables.
====================

Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>