genetlink: add and use genl_set_err()

Add a static inline to generic netlink to wrap netlink_set_err()
to make it easier to use here - use it in openvswitch (the only
generic netlink user of netlink_set_err()).
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/genetlink.h

@@ -351,5 +351,19 @@ static inline struct sk_buff *genlmsg_new(size_t payload, gfp_t flags)
 	return nlmsg_new(genlmsg_total_size(payload), flags);
 }
 
+/**
+ * genl_set_err - report error to genetlink broadcast listeners
+ * @net: the network namespace to report the error to
+ * @portid: the PORTID of a process that we want to skip (if any)
+ * @group: the broadcast group that will notice the error
+ * @code: error code, must be negative (as usual in kernelspace)
+ *
+ * This function returns the number of broadcast listeners that have set the
+ * NETLINK_RECV_NO_ENOBUFS socket option.
+ */
+static inline int genl_set_err(struct net *net, u32 portid, u32 group, int code)
+{
+	return netlink_set_err(net->genl_sock, portid, group, code);
+}
 
 #endif	/* __NET_GENERIC_NETLINK_H */

net/openvswitch/datapath.c

@@ -879,8 +879,8 @@ static int ovs_flow_cmd_new_or_set(struct sk_buff *skb, struct genl_info *info)
 	if (!IS_ERR(reply))
 		ovs_notify(reply, info, &ovs_dp_flow_multicast_group);
 	else
-		netlink_set_err(sock_net(skb->sk)->genl_sock, 0,
-				ovs_dp_flow_multicast_group.id, PTR_ERR(reply));
+		genl_set_err(sock_net(skb->sk), 0,
+			     ovs_dp_flow_multicast_group.id, PTR_ERR(reply));
 	return 0;
 
 err_flow_free:
@@ -1326,8 +1326,8 @@ static int ovs_dp_cmd_set(struct sk_buff *skb, struct genl_info *info)
 				      info->snd_seq, OVS_DP_CMD_NEW);
 	if (IS_ERR(reply)) {
 		err = PTR_ERR(reply);
-		netlink_set_err(sock_net(skb->sk)->genl_sock, 0,
-				ovs_dp_datapath_multicast_group.id, err);
+		genl_set_err(sock_net(skb->sk), 0,
+			     ovs_dp_datapath_multicast_group.id, err);
 		err = 0;
 		goto unlock;
 	}

net/openvswitch/dp_notify.c

@@ -34,9 +34,9 @@ static void dp_detach_port_notify(struct vport *vport)
 					  OVS_VPORT_CMD_DEL);
 	ovs_dp_detach_port(vport);
 	if (IS_ERR(notify)) {
-		netlink_set_err(ovs_dp_get_net(dp)->genl_sock, 0,
-				ovs_dp_vport_multicast_group.id,
-				PTR_ERR(notify));
+		genl_set_err(ovs_dp_get_net(dp), 0,
+			     ovs_dp_vport_multicast_group.id,
+			     PTR_ERR(notify));
 		return;
 	}