bridge: netlink: export per-vlan stats

Add a new LINK_XSTATS_TYPE_BRIDGE attribute and implement the
RTM_GETSTATS callbacks for IFLA_STATS_LINK_XSTATS (fill_linkxstats and
get_linkxstats_size) in order to export the per-vlan stats.
The paddings were added because soon these fields will be needed for
per-port per-vlan stats (or something else if someone beats me to it) so
avoiding at least a few more netlink attributes.

Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 7fba1f0..a5343c7 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -1234,6 +1234,69 @@
 	return 0;
 }
 
+static size_t br_get_linkxstats_size(const struct net_device *dev)
+{
+	struct net_bridge *br = netdev_priv(dev);
+	struct net_bridge_vlan_group *vg;
+	struct net_bridge_vlan *v;
+	int numvls = 0;
+
+	vg = br_vlan_group(br);
+	if (!vg)
+		return 0;
+
+	/* we need to count all, even placeholder entries */
+	list_for_each_entry(v, &vg->vlan_list, vlist)
+		numvls++;
+
+	/* account for the vlans and the link xstats type nest attribute */
+	return numvls * nla_total_size(sizeof(struct bridge_vlan_xstats)) +
+	       nla_total_size(0);
+}
+
+static int br_fill_linkxstats(struct sk_buff *skb, const struct net_device *dev,
+			      int *prividx)
+{
+	struct net_bridge *br = netdev_priv(dev);
+	struct net_bridge_vlan_group *vg;
+	struct net_bridge_vlan *v;
+	struct nlattr *nest;
+	int vl_idx = 0;
+
+	vg = br_vlan_group(br);
+	if (!vg)
+		goto out;
+	nest = nla_nest_start(skb, LINK_XSTATS_TYPE_BRIDGE);
+	if (!nest)
+		return -EMSGSIZE;
+	list_for_each_entry(v, &vg->vlan_list, vlist) {
+		struct bridge_vlan_xstats vxi;
+		struct br_vlan_stats stats;
+
+		if (vl_idx++ < *prividx)
+			continue;
+		memset(&vxi, 0, sizeof(vxi));
+		vxi.vid = v->vid;
+		br_vlan_get_stats(v, &stats);
+		vxi.rx_bytes = stats.rx_bytes;
+		vxi.rx_packets = stats.rx_packets;
+		vxi.tx_bytes = stats.tx_bytes;
+		vxi.tx_packets = stats.tx_packets;
+
+		if (nla_put(skb, BRIDGE_XSTATS_VLAN, sizeof(vxi), &vxi))
+			goto nla_put_failure;
+	}
+	nla_nest_end(skb, nest);
+	*prividx = 0;
+out:
+	return 0;
+
+nla_put_failure:
+	nla_nest_end(skb, nest);
+	*prividx = vl_idx;
+
+	return -EMSGSIZE;
+}
 
 static struct rtnl_af_ops br_af_ops __read_mostly = {
 	.family			= AF_BRIDGE,
@@ -1252,6 +1315,8 @@
 	.dellink		= br_dev_delete,
 	.get_size		= br_get_size,
 	.fill_info		= br_fill_info,
+	.fill_linkxstats	= br_fill_linkxstats,
+	.get_linkxstats_size	= br_get_linkxstats_size,
 
 	.slave_maxtype		= IFLA_BRPORT_MAX,
 	.slave_policy		= br_port_policy,