net: af_netlink should update its inuse counter

In order to have relevant information for NETLINK protocol, in
/proc/net/protocols, we should use sock_prot_inuse_add() to
update a (percpu and pernamespace) counter of inuse sockets.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 480184a..a2071dc 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -452,6 +452,7 @@
 	if (err < 0)
 		goto out_module;
 
+	sock_prot_inuse_add(net, &netlink_proto, 1);
 	nlk = nlk_sk(sock->sk);
 	nlk->module = module;
 out:
@@ -511,6 +512,7 @@
 	kfree(nlk->groups);
 	nlk->groups = NULL;
 
+	sock_prot_inuse_add(sock_net(sk), &netlink_proto, -1);
 	sock_put(sk);
 	return 0;
 }