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>

1 files changed, 9 insertions, 1 deletions

diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
index 2c8095a5d824..0c39e0f6da09 100644
--- a/net/bridge/br_device.c
+++ b/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;