net: bridge: add support for IGMP/MLD stats and export them via netlink

This patch adds stats support for the currently used IGMP/MLD types by the
bridge. The stats are per-port (plus one stat per-bridge) and per-direction
(RX/TX). The stats are exported via netlink via the new linkxstats API
(RTM_GETSTATS). In order to minimize the performance impact, a new option
is used to enable/disable the stats - multicast_stats_enabled, similar to
the recent vlan stats. Also in order to avoid multiple IGMP/MLD type
lookups and checks, we make use of the current "igmp" member of the bridge
private skb->cb region to record the type on Rx (both host-generated and
external packets pass by multicast_rcv()). We can do that since the igmp
member was used as a boolean and all the valid IGMP/MLD types are positive
values. The normal bridge fast-path is not affected at all, the only
affected paths are the flooding ones and since we make use of the IGMP/MLD
type, we can quickly determine if the packet should be counted using
cache-hot data (cb's igmp member). We add counters for:
* IGMP Queries
* IGMP Leaves
* IGMP v1/v2/v3 reports

* MLD Queries
* MLD Leaves
* MLD v1/v2 reports

These are invaluable when monitoring or debugging complex multicast setups
with bridges.

Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/if_bridge.h

@@ -247,8 +247,34 @@ enum {
 enum {
 	BRIDGE_XSTATS_UNSPEC,
 	BRIDGE_XSTATS_VLAN,
+	BRIDGE_XSTATS_MCAST,
+	BRIDGE_XSTATS_PAD,
 	__BRIDGE_XSTATS_MAX
 };
 #define BRIDGE_XSTATS_MAX (__BRIDGE_XSTATS_MAX - 1)
 
+enum {
+	BR_MCAST_DIR_RX,
+	BR_MCAST_DIR_TX,
+	BR_MCAST_DIR_SIZE
+};
+
+/* IGMP/MLD statistics */
+struct br_mcast_stats {
+	__u64 igmp_queries[BR_MCAST_DIR_SIZE];
+	__u64 igmp_leaves[BR_MCAST_DIR_SIZE];
+	__u64 igmp_v1reports[BR_MCAST_DIR_SIZE];
+	__u64 igmp_v2reports[BR_MCAST_DIR_SIZE];
+	__u64 igmp_v3reports[BR_MCAST_DIR_SIZE];
+	__u64 igmp_parse_errors;
+
+	__u64 mld_queries[BR_MCAST_DIR_SIZE];
+	__u64 mld_leaves[BR_MCAST_DIR_SIZE];
+	__u64 mld_v1reports[BR_MCAST_DIR_SIZE];
+	__u64 mld_v2reports[BR_MCAST_DIR_SIZE];
+	__u64 mld_parse_errors;
+
+	__u64 mcast_bytes[BR_MCAST_DIR_SIZE];
+	__u64 mcast_packets[BR_MCAST_DIR_SIZE];
+};
 #endif /* _UAPI_LINUX_IF_BRIDGE_H */

include/uapi/linux/if_link.h

@@ -273,6 +273,7 @@ enum {
 	IFLA_BR_VLAN_DEFAULT_PVID,
 	IFLA_BR_PAD,
 	IFLA_BR_VLAN_STATS_ENABLED,
+	IFLA_BR_MCAST_STATS_ENABLED,
 	__IFLA_BR_MAX,
 };
 

net/bridge/br_device.c

@@ -104,8 +104,16 @@ static int br_dev_init(struct net_device *dev)
 		return -ENOMEM;
 
 	err = br_vlan_init(br);
-	if (err)
+	if (err) {
 		free_percpu(br->stats);
+		return err;
+	}
+
+	err = br_multicast_init_stats(br);
+	if (err) {
+		free_percpu(br->stats);
+		br_vlan_flush(br);
+	}
 	br_set_lockdep_class(dev);
 
 	return err;

net/bridge/br_forward.c

@@ -198,8 +198,10 @@ static void br_flood(struct net_bridge *br, struct sk_buff *skb,
 					   struct sk_buff *skb),
 		     bool unicast)
 {
-	struct net_bridge_port *p;
+	u8 igmp_type = br_multicast_igmp_type(skb);
+	__be16 proto = skb->protocol;
 	struct net_bridge_port *prev;
+	struct net_bridge_port *p;
 
 	prev = NULL;
 
@@ -218,6 +220,9 @@ static void br_flood(struct net_bridge *br, struct sk_buff *skb,
 		prev = maybe_deliver(prev, p, skb, __packet_hook);
 		if (IS_ERR(prev))
 			goto out;
+		if (prev == p)
+			br_multicast_count(p->br, p, proto, igmp_type,
+					   BR_MCAST_DIR_TX);
 	}
 
 	if (!prev)
@@ -257,9 +262,12 @@ static void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 					struct sk_buff *skb))
 {
 	struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
+	u8 igmp_type = br_multicast_igmp_type(skb);
 	struct net_bridge *br = netdev_priv(dev);
 	struct net_bridge_port *prev = NULL;
 	struct net_bridge_port_group *p;
+	__be16 proto = skb->protocol;
+
 	struct hlist_node *rp;
 
 	rp = rcu_dereference(hlist_first_rcu(&br->router_list));
@@ -277,6 +285,9 @@ static void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 		prev = maybe_deliver(prev, port, skb, __packet_hook);
 		if (IS_ERR(prev))
 			goto out;
+		if (prev == port)
+			br_multicast_count(port->br, port, proto, igmp_type,
+					   BR_MCAST_DIR_TX);
 
 		if ((unsigned long)lport >= (unsigned long)port)
 			p = rcu_dereference(p->next);

net/bridge/br_if.c

@@ -345,8 +345,8 @@ static int find_portno(struct net_bridge *br)
 static struct net_bridge_port *new_nbp(struct net_bridge *br,
 				       struct net_device *dev)
 {
-	int index;
 	struct net_bridge_port *p;
+	int index, err;
 
 	index = find_portno(br);
 	if (index < 0)
@@ -366,7 +366,12 @@ static struct net_bridge_port *new_nbp(struct net_bridge *br,
 	br_init_port(p);
 	br_set_state(p, BR_STATE_DISABLED);
 	br_stp_port_timer_init(p);
-	br_multicast_add_port(p);
+	err = br_multicast_add_port(p);
+	if (err) {
+		dev_put(dev);
+		kfree(p);
+		p = ERR_PTR(err);
+	}
 
 	return p;
 }

net/bridge/br_input.c

@@ -60,6 +60,9 @@ static int br_pass_frame_up(struct sk_buff *skb)
 	skb = br_handle_vlan(br, vg, skb);
 	if (!skb)
 		return NET_RX_DROP;
+	/* update the multicast stats if the packet is IGMP/MLD */
+	br_multicast_count(br, NULL, skb->protocol, br_multicast_igmp_type(skb),
+			   BR_MCAST_DIR_TX);
 
 	return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
 		       dev_net(indev), NULL, skb, indev, NULL,