[NET]: Make rtnetlink infrastructure network namespace aware (v3)

After this patch none of the netlink callback support anything
except the initial network namespace but the rtnetlink infrastructure
now handles multiple network namespaces.

Changes from v2:
- IPv6 addrlabel processing

Changes from v1:
- no need for special rtnl_unlock handling
- fixed IPv6 ndisc

Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index b2531f8..b87f9d2 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -1049,7 +1049,8 @@
 		&ipv6_hdr(ra)->saddr);
 	nlmsg_end(skb, nlh);
 
-	err = rtnl_notify(skb, 0, RTNLGRP_ND_USEROPT, NULL, GFP_ATOMIC);
+	err = rtnl_notify(skb, &init_net, 0, RTNLGRP_ND_USEROPT, NULL,
+			  GFP_ATOMIC);
 	if (err < 0)
 		goto errout;
 
@@ -1059,7 +1060,7 @@
 	nlmsg_free(skb);
 	err = -EMSGSIZE;
 errout:
-	rtnl_set_sk_err(RTNLGRP_ND_USEROPT, err);
+	rtnl_set_sk_err(&init_net, RTNLGRP_ND_USEROPT, err);
 }
 
 static void ndisc_router_discovery(struct sk_buff *skb)