openvswitch: restore OVS_FLOW_CMD_NEW notifications

Since commit fb5d1e9e127a ("openvswitch: Build flow cmd netlink reply only if needed."),
the new flows are not notified to the listeners of OVS_FLOW_MCGROUP.

This commit fixes the problem by using the genl function, ie
genl_has_listerners() instead of netlink_has_listeners().

Signed-off-by: Samuel Gauthier <samuel.gauthier@6wind.com>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Acked-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/openvswitch/datapath.c

@@ -78,11 +78,12 @@ static const struct genl_multicast_group ovs_dp_vport_multicast_group = {
 
 /* Check if need to build a reply message.
  * OVS userspace sets the NLM_F_ECHO flag if it needs the reply. */
-static bool ovs_must_notify(struct genl_info *info,
-			    const struct genl_multicast_group *grp)
+static bool ovs_must_notify(struct genl_family *family, struct genl_info *info,
+			    unsigned int group)
 {
 	return info->nlhdr->nlmsg_flags & NLM_F_ECHO ||
-		netlink_has_listeners(genl_info_net(info)->genl_sock, 0);
+	       genl_has_listeners(family, genl_info_net(info)->genl_sock,
+				  group);
 }
 
 static void ovs_notify(struct genl_family *family,
@@ -763,7 +764,7 @@ static struct sk_buff *ovs_flow_cmd_alloc_info(const struct sw_flow_actions *act
 {
 	struct sk_buff *skb;
 
-	if (!always && !ovs_must_notify(info, &ovs_dp_flow_multicast_group))
+	if (!always && !ovs_must_notify(&dp_flow_genl_family, info, 0))
 		return NULL;
 
 	skb = genlmsg_new_unicast(ovs_flow_cmd_msg_size(acts), info, GFP_KERNEL);