net: Convert dccp_v4_ops

These pernet_operations create and destroy net::dccp::v4_ctl_sk.
It looks like another pernet_operations don't want to send
dccp packets to dying or creating net. Batch method similar
to ipv4/ipv6 sockets and it has to be safe to be executed
in parallel with anything else. So, we mark them as async.
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dccp/ipv4.c

@@ -1031,6 +1031,7 @@ static struct pernet_operations dccp_v4_ops = {
 	.init	= dccp_v4_init_net,
 	.exit	= dccp_v4_exit_net,
 	.exit_batch = dccp_v4_exit_batch,
+	.async	= true,
 };
 
 static int __init dccp_v4_init(void)