netns: notify netns id events

With this patch, netns ids that are created and deleted are advertised into the
group RTNLGRP_NSID.

Because callers of rtnl_net_notifyid() already know the id of the peer, there is
no need to call __peernet2id() in rtnl_net_fill().

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/uapi/linux/rtnetlink.h b/include/uapi/linux/rtnetlink.h
index bea910f..974db03 100644
--- a/include/uapi/linux/rtnetlink.h
+++ b/include/uapi/linux/rtnetlink.h
@@ -134,6 +134,8 @@
 
 	RTM_NEWNSID = 88,
 #define RTM_NEWNSID RTM_NEWNSID
+	RTM_DELNSID = 89,
+#define RTM_DELNSID RTM_DELNSID
 	RTM_GETNSID = 90,
 #define RTM_GETNSID RTM_GETNSID
 
@@ -635,6 +637,8 @@
 #define RTNLGRP_MDB		RTNLGRP_MDB
 	RTNLGRP_MPLS_ROUTE,
 #define RTNLGRP_MPLS_ROUTE	RTNLGRP_MPLS_ROUTE
+	RTNLGRP_NSID,
+#define RTNLGRP_NSID		RTNLGRP_NSID
 	__RTNLGRP_MAX
 };
 #define RTNLGRP_MAX	(__RTNLGRP_MAX - 1)