Merge branch 'bridgge-mcast'

Nikolay Aleksandrov says:

====================
net: bridge: mcast: dump querier state

This set adds the ability to dump the current multicast querier state.
This is extremely useful when debugging multicast issues, we've had
many cases of unexpected queriers causing strange behaviour and mcast
test failures. The first patch changes the querier struct to record
a port device's ifindex instead of a pointer to the port itself so we
can later retrieve it, I chose this way because it's much simpler
and doesn't require us to do querier port ref counting, it is best
effort anyway. Then patch 02 makes the querier address/port updates
consistent via a combination of multicast_lock and seqcount, so readers
can only use seqcount to get a consistent snapshot of address and port.
Patch 03 is a minor cleanup in preparation for the dump support, it
consolidates IPv4 and IPv6 querier selection paths as they share most of
the logic (except address comparisons of course). Finally the last three
patches add the new querier state dumping support, for the bridge's
global multicast context we embed the BRIDGE_QUERIER_xxx attributes
into IFLA_BR_MCAST_QUERIER_STATE and for the per-vlan global mcast
contexts we embed them into BRIDGE_VLANDB_GOPTS_MCAST_QUERIER_STATE.

The structure is:
  [IFLA_BR_MCAST_QUERIER_STATE / BRIDGE_VLANDB_GOPTS_MCAST_QUERIER_STATE]
  `[BRIDGE_QUERIER_IP_ADDRESS] - ip address of the querier
  `[BRIDGE_QUERIER_IP_PORT]    - bridge port ifindex where the querier was
                                 seen (set only if external querier)
  `[BRIDGE_QUERIER_IP_OTHER_TIMER]   -  other querier timeout
  `[BRIDGE_QUERIER_IPV6_ADDRESS] - ip address of the querier
  `[BRIDGE_QUERIER_IPV6_PORT]    - bridge port ifindex where the querier
                                   was seen (set only if external querier)
  `[BRIDGE_QUERIER_IPV6_OTHER_TIMER]   -  other querier timeout

Later we can also add IGMP version of seen queriers and last seen values
from the queries.
====================

include/uapi/linux/if_bridge.h

@@ -563,6 +563,7 @@ enum {
 	BRIDGE_VLANDB_GOPTS_MCAST_QUERIER,
 	BRIDGE_VLANDB_GOPTS_MCAST_ROUTER,
 	BRIDGE_VLANDB_GOPTS_MCAST_ROUTER_PORTS,
+	BRIDGE_VLANDB_GOPTS_MCAST_QUERIER_STATE,
 	__BRIDGE_VLANDB_GOPTS_MAX
 };
 #define BRIDGE_VLANDB_GOPTS_MAX (__BRIDGE_VLANDB_GOPTS_MAX - 1)
@@ -770,4 +771,17 @@ struct br_boolopt_multi {
 	__u32 optval;
 	__u32 optmask;
 };
+
+enum {
+	BRIDGE_QUERIER_UNSPEC,
+	BRIDGE_QUERIER_IP_ADDRESS,
+	BRIDGE_QUERIER_IP_PORT,
+	BRIDGE_QUERIER_IP_OTHER_TIMER,
+	BRIDGE_QUERIER_PAD,
+	BRIDGE_QUERIER_IPV6_ADDRESS,
+	BRIDGE_QUERIER_IPV6_PORT,
+	BRIDGE_QUERIER_IPV6_OTHER_TIMER,
+	__BRIDGE_QUERIER_MAX
+};
+#define BRIDGE_QUERIER_MAX (__BRIDGE_QUERIER_MAX - 1)
 #endif /* _UAPI_LINUX_IF_BRIDGE_H */

include/uapi/linux/if_link.h

@@ -479,6 +479,7 @@ enum {
 	IFLA_BR_MCAST_MLD_VERSION,
 	IFLA_BR_VLAN_STATS_PER_PORT,
 	IFLA_BR_MULTI_BOOLOPT,
+	IFLA_BR_MCAST_QUERIER_STATE,
 	__IFLA_BR_MAX,
 };
 

net/bridge/br_netlink.c

@@ -1501,6 +1501,7 @@ static size_t br_get_size(const struct net_device *brdev)
 	       nla_total_size_64bit(sizeof(u64)) + /* IFLA_BR_MCAST_STARTUP_QUERY_INTVL */
 	       nla_total_size(sizeof(u8)) +	/* IFLA_BR_MCAST_IGMP_VERSION */
 	       nla_total_size(sizeof(u8)) +	/* IFLA_BR_MCAST_MLD_VERSION */
+	       br_multicast_querier_state_size() + /* IFLA_BR_MCAST_QUERIER_STATE */
 #endif
 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
 	       nla_total_size(sizeof(u8)) +     /* IFLA_BR_NF_CALL_IPTABLES */
@@ -1587,7 +1588,9 @@ static int br_fill_info(struct sk_buff *skb, const struct net_device *brdev)
 	    nla_put_u32(skb, IFLA_BR_MCAST_STARTUP_QUERY_CNT,
 			br->multicast_ctx.multicast_startup_query_count) ||
 	    nla_put_u8(skb, IFLA_BR_MCAST_IGMP_VERSION,
-		       br->multicast_ctx.multicast_igmp_version))
+		       br->multicast_ctx.multicast_igmp_version) ||
+	    br_multicast_dump_querier_state(skb, &br->multicast_ctx,
+					    IFLA_BR_MCAST_QUERIER_STATE))
 		return -EMSGSIZE;
 #if IS_ENABLED(CONFIG_IPV6)
 	if (nla_put_u8(skb, IFLA_BR_MCAST_MLD_VERSION,

net/bridge/br_private.h

@@ -81,7 +81,8 @@ struct bridge_mcast_other_query {
 /* selected querier */
 struct bridge_mcast_querier {
 	struct br_ip addr;
-	struct net_bridge_port __rcu	*port;
+	int port_ifidx;
+	seqcount_t seq;
 };
 
 /* IGMP/MLD statistics */
@@ -947,6 +948,10 @@ int br_mdb_replay(struct net_device *br_dev, struct net_device *dev,
 		  struct netlink_ext_ack *extack);
 int br_rports_fill_info(struct sk_buff *skb,
 			const struct net_bridge_mcast *brmctx);
+int br_multicast_dump_querier_state(struct sk_buff *skb,
+				    const struct net_bridge_mcast *brmctx,
+				    int nest_attr);
+size_t br_multicast_querier_state_size(void);
 
 static inline bool br_group_is_l2(const struct br_ip *group)
 {

net/bridge/br_vlan_options.c

@@ -299,7 +299,9 @@ bool br_vlan_global_opts_fill(struct sk_buff *skb, u16 vid, u16 vid_range,
 	    nla_put_u8(skb, BRIDGE_VLANDB_GOPTS_MCAST_QUERIER,
 		       v_opts->br_mcast_ctx.multicast_querier) ||
 	    nla_put_u8(skb, BRIDGE_VLANDB_GOPTS_MCAST_ROUTER,
-		       v_opts->br_mcast_ctx.multicast_router))
+		       v_opts->br_mcast_ctx.multicast_router) ||
+	    br_multicast_dump_querier_state(skb, &v_opts->br_mcast_ctx,
+					    BRIDGE_VLANDB_GOPTS_MCAST_QUERIER_STATE))
 		goto out_err;
 
 	clockval = jiffies_to_clock_t(v_opts->br_mcast_ctx.multicast_last_member_interval);
@@ -379,6 +381,7 @@ static size_t rtnl_vlan_global_opts_nlmsg_size(void)
 		+ nla_total_size(sizeof(u64)) /* BRIDGE_VLANDB_GOPTS_MCAST_STARTUP_QUERY_INTVL */
 		+ nla_total_size(sizeof(u8)) /* BRIDGE_VLANDB_GOPTS_MCAST_QUERIER */
 		+ nla_total_size(sizeof(u8)) /* BRIDGE_VLANDB_GOPTS_MCAST_ROUTER */
+		+ br_multicast_querier_state_size() /* BRIDGE_VLANDB_GOPTS_MCAST_QUERIER_STATE */
 #endif
 		+ nla_total_size(sizeof(u16)); /* BRIDGE_VLANDB_GOPTS_RANGE */
 }