v2:
 - Use do_dump_opt in dump_socket to not call
   lookup_socket redundantly

v3:
 - use getsockopt to check that unconnected
   socket has no peername and it's not listening
 - do test only socket protocol since family and
   type will be called in dump_one_inet_fd.

v4:
 - Move proto tests to can_dump_inet_sk
 - Use SOL_TCP/TCP_INFO to gather info about tcp sockets

v5:
 - hash unconnected sockets to run BUG_ON(already-dumped) logic
 - no default value for sk->wqlen, use zero from xzalloc
 - drop bogus xfree on error
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>