genetlink: Add genl_notify()

Open vSwitch uses Generic Netlink interface for communication
between userspace and kernel module. genl_notify() is used
for sending notification back to userspace.

genl_notify() is analogous to rtnl_notify() but uses genl_sock
instead of rtnl.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
diff --git a/include/net/genetlink.h b/include/net/genetlink.h
index 82d8d09..7db3299 100644
--- a/include/net/genetlink.h
+++ b/include/net/genetlink.h
@@ -128,6 +128,8 @@
 				  struct genl_multicast_group *grp);
 extern void genl_unregister_mc_group(struct genl_family *family,
 				     struct genl_multicast_group *grp);
+extern void genl_notify(struct sk_buff *skb, struct net *net, u32 pid,
+			u32 group, struct nlmsghdr *nlh, gfp_t flags);
 
 /**
  * genlmsg_put - Add generic netlink header to netlink message