Merge branch 'bridge_multicast_exports'

Linus Lüssing says:

====================
bridge: multicast snooping patches / exports

The first patch is simply a cosmetic patch. So far I (and maybe others
too?) have been regularly confusing these two structs, therefore I'd
suggest renaming them and therefore making the follow-up patches easier
to understand and nicer to fit in.

The second patch fixes a minor issue, but probably not worth for stable.

On the other hand the first two patches are also preparations for the
third and fourth patch:

These two patches are exporting functionality needed to marry the bridge
multicast snooping with the batman-adv multicast optimizations recently
added for the 3.15 kernel, allowing to use these optimzations in common
setups having a bridge on top of e.g. bat0, too. So far these bridged
setups would fall back to simple flooding through the batman-adv mesh
network for any multicast packet entering bat0.

More information about the batman-adv multicast optimizations currently
implemented can be found here:

http://www.open-mesh.org/projects/batman-adv/wiki/Basic-multicast-optimizations

The integration on the batman-adv side could afterwards look like this,
for instance:

http://git.open-mesh.org/batman-adv.git/commitdiff/576b59dd3e34737c702e548b21fa72059262f796?hp=f95ce7131746c65fbcdffcf2089cab59e2c2f7ac
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 326 insertions, 113 deletions

diff --git a/include/linux/if_bridge.h b/include/linux/if_bridge.h
index 1085ffeef956..fd22789d7b2e 100644
--- a/include/linux/if_bridge.h
+++ b/include/linux/if_bridge.h
@@ -16,9 +16,28 @@
 #include <linux/netdevice.h>
 #include <uapi/linux/if_bridge.h>
 
+struct br_ip {
+        union {
+                __be32  ip4;
+#if IS_ENABLED(CONFIG_IPV6)
+                struct in6_addr ip6;
+#endif
+        } u;
+        __be16          proto;
+        __u16           vid;
+};
+
+struct br_ip_list {
+        struct list_head list;
+        struct br_ip addr;
+};
+
 extern void brioctl_set(int (*ioctl_hook)(struct net *, unsigned int, void __user *));
 
 typedef int br_should_route_hook_t(struct sk_buff *skb);
 extern br_should_route_hook_t __rcu *br_should_route_hook;
+int br_multicast_list_adjacent(struct net_device *dev,
+                               struct list_head *br_ip_list);
+bool br_multicast_has_querier_adjacent(struct net_device *dev, int proto);
 
 #endif
diff --git a/net/bridge/br_mdb.c b/net/bridge/br_mdb.c
index b7b1914dfa25..5df05269d17a 100644
--- a/net/bridge/br_mdb.c
+++ b/net/bridge/br_mdb.c
@@ -418,13 +418,13 @@ static int __br_mdb_del(struct net_bridge *br, struct br_mdb_entry *entry)
 
         ip.proto = entry->addr.proto;
         if (ip.proto == htons(ETH_P_IP)) {
-                if (timer_pending(&br->ip4_querier.timer))
+                if (timer_pending(&br->ip4_other_query.timer))
                         return -EBUSY;
 
                 ip.u.ip4 = entry->addr.u.ip4;
 #if IS_ENABLED(CONFIG_IPV6)
         } else {
-                if (timer_pending(&br->ip6_querier.timer))
+                if (timer_pending(&br->ip6_other_query.timer))
                         return -EBUSY;
 
                 ip.u.ip6 = entry->addr.u.ip6;
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 7b757b5dc773..cd3cf394c477 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -11,6 +11,7 @@
  */
 
 #include <linux/err.h>
+#include <linux/export.h>
 #include <linux/if_ether.h>
 #include <linux/igmp.h>
 #include <linux/jhash.h>
@@ -35,7 +36,7 @@
 #include "br_private.h"
 
 static void br_multicast_start_querier(struct net_bridge *br,
-                                       struct bridge_mcast_query *query);
+                                       struct bridge_mcast_own_query *query);
 unsigned int br_mdb_rehash_seq;
 
 static inline int br_ip_equal(const struct br_ip *a, const struct br_ip *b)
@@ -761,7 +762,7 @@ static void br_multicast_local_router_expired(unsigned long data)
 }
 
 static void br_multicast_querier_expired(struct net_bridge *br,
-                                         struct bridge_mcast_query *query)
+                                         struct bridge_mcast_own_query *query)
 {
         spin_lock(&br->multicast_lock);
         if (!netif_running(br->dev) || br->multicast_disabled)
@@ -777,7 +778,7 @@ static void br_ip4_multicast_querier_expired(unsigned long data)
 {
         struct net_bridge *br = (void *)data;
 
-        br_multicast_querier_expired(br, &br->ip4_query);
+        br_multicast_querier_expired(br, &br->ip4_own_query);
 }
 
 #if IS_ENABLED(CONFIG_IPV6)
@@ -785,10 +786,22 @@ static void br_ip6_multicast_querier_expired(unsigned long data)
 {
         struct net_bridge *br = (void *)data;
 
-        br_multicast_querier_expired(br, &br->ip6_query);
+        br_multicast_querier_expired(br, &br->ip6_own_query);
 }
 #endif
 
+static void br_multicast_select_own_querier(struct net_bridge *br,
+                                            struct br_ip *ip,
+                                            struct sk_buff *skb)
+{
+        if (ip->proto == htons(ETH_P_IP))
+                br->ip4_querier.addr.u.ip4 = ip_hdr(skb)->saddr;
+#if IS_ENABLED(CONFIG_IPV6)
+        else
+                br->ip6_querier.addr.u.ip6 = ipv6_hdr(skb)->saddr;
+#endif
+}
+
 static void __br_multicast_send_query(struct net_bridge *br,
                                       struct net_bridge_port *port,
                                       struct br_ip *ip)
@@ -804,17 +817,19 @@ static void __br_multicast_send_query(struct net_bridge *br,
                 skb->dev = port->dev;
                 NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
                         dev_queue_xmit);
-        } else
+        } else {
+                br_multicast_select_own_querier(br, ip, skb);
                 netif_rx(skb);
+        }
 }
 
 static void br_multicast_send_query(struct net_bridge *br,
                                     struct net_bridge_port *port,
-                                    struct bridge_mcast_query *query)
+                                    struct bridge_mcast_own_query *own_query)
 {
         unsigned long time;
         struct br_ip br_group;
-        struct bridge_mcast_querier *querier = NULL;
+        struct bridge_mcast_other_query *other_query = NULL;
 
         if (!netif_running(br->dev) || br->multicast_disabled ||
             !br->multicast_querier)
@@ -822,31 +837,32 @@ static void br_multicast_send_query(struct net_bridge *br,
 
         memset(&br_group.u, 0, sizeof(br_group.u));
 
-        if (port ? (query == &port->ip4_query) :
-                   (query == &br->ip4_query)) {
-                querier = &br->ip4_querier;
+        if (port ? (own_query == &port->ip4_own_query) :
+                   (own_query == &br->ip4_own_query)) {
+                other_query = &br->ip4_other_query;
                 br_group.proto = htons(ETH_P_IP);
 #if IS_ENABLED(CONFIG_IPV6)
         } else {
-                querier = &br->ip6_querier;
+                other_query = &br->ip6_other_query;
                 br_group.proto = htons(ETH_P_IPV6);
 #endif
         }
 
-        if (!querier || timer_pending(&querier->timer))
+        if (!other_query || timer_pending(&other_query->timer))
                 return;
 
         __br_multicast_send_query(br, port, &br_group);
 
         time = jiffies;
-        time += query->startup_sent < br->multicast_startup_query_count ?
+        time += own_query->startup_sent < br->multicast_startup_query_count ?
                 br->multicast_startup_query_interval :
                 br->multicast_query_interval;
-        mod_timer(&query->timer, time);
+        mod_timer(&own_query->timer, time);
 }
 
-static void br_multicast_port_query_expired(struct net_bridge_port *port,
-                                            struct bridge_mcast_query *query)
+static void
+br_multicast_port_query_expired(struct net_bridge_port *port,
+                                struct bridge_mcast_own_query *query)
 {
         struct net_bridge *br = port->br;
 
@@ -868,7 +884,7 @@ static void br_ip4_multicast_port_query_expired(unsigned long data)
 {
         struct net_bridge_port *port = (void *)data;
 
-        br_multicast_port_query_expired(port, &port->ip4_query);
+        br_multicast_port_query_expired(port, &port->ip4_own_query);
 }
 
 #if IS_ENABLED(CONFIG_IPV6)
@@ -876,7 +892,7 @@ static void br_ip6_multicast_port_query_expired(unsigned long data)
 {
         struct net_bridge_port *port = (void *)data;
 
-        br_multicast_port_query_expired(port, &port->ip6_query);
+        br_multicast_port_query_expired(port, &port->ip6_own_query);
 }
 #endif
 
@@ -886,11 +902,11 @@ void br_multicast_add_port(struct net_bridge_port *port)
 
         setup_timer(&port->multicast_router_timer, br_multicast_router_expired,
                     (unsigned long)port);
-        setup_timer(&port->ip4_query.timer, br_ip4_multicast_port_query_expired,
-                    (unsigned long)port);
+        setup_timer(&port->ip4_own_query.timer,
+                    br_ip4_multicast_port_query_expired, (unsigned long)port);
 #if IS_ENABLED(CONFIG_IPV6)
-        setup_timer(&port->ip6_query.timer, br_ip6_multicast_port_query_expired,
-                    (unsigned long)port);
+        setup_timer(&port->ip6_own_query.timer,
+                    br_ip6_multicast_port_query_expired, (unsigned long)port);
 #endif
 }
 
@@ -899,7 +915,7 @@ void br_multicast_del_port(struct net_bridge_port *port)
         del_timer_sync(&port->multicast_router_timer);
 }
 
-static void br_multicast_enable(struct bridge_mcast_query *query)
+static void br_multicast_enable(struct bridge_mcast_own_query *query)
 {
         query->startup_sent = 0;
 
@@ -916,9 +932,9 @@ void br_multicast_enable_port(struct net_bridge_port *port)
         if (br->multicast_disabled || !netif_running(br->dev))
                 goto out;
 
-        br_multicast_enable(&port->ip4_query);
+        br_multicast_enable(&port->ip4_own_query);
 #if IS_ENABLED(CONFIG_IPV6)
-        br_multicast_enable(&port->ip6_query);
+        br_multicast_enable(&port->ip6_own_query);
 #endif
 
 out:
@@ -938,9 +954,9 @@ void br_multicast_disable_port(struct net_bridge_port *port)
         if (!hlist_unhashed(&port->rlist))
                 hlist_del_init_rcu(&port->rlist);
         del_timer(&port->multicast_router_timer);
-        del_timer(&port->ip4_query.timer);
+        del_timer(&port->ip4_own_query.timer);
 #if IS_ENABLED(CONFIG_IPV6)
-        del_timer(&port->ip6_query.timer);
+        del_timer(&port->ip6_own_query.timer);
 #endif
         spin_unlock(&br->multicast_lock);
 }
@@ -1064,15 +1080,80 @@ static int br_ip6_multicast_mld2_report(struct net_bridge *br,
 }
 #endif
 
+static bool br_ip4_multicast_select_querier(struct net_bridge *br,
+                                            struct net_bridge_port *port,
+                                            __be32 saddr)
+{
+        if (!timer_pending(&br->ip4_own_query.timer) &&
+            !timer_pending(&br->ip4_other_query.timer))
+                goto update;
+
+        if (!br->ip4_querier.addr.u.ip4)
+                goto update;
+
+        if (ntohl(saddr) <= ntohl(br->ip4_querier.addr.u.ip4))
+                goto update;
+
+        return false;
+
+update:
+        br->ip4_querier.addr.u.ip4 = saddr;
+
+        /* update protected by general multicast_lock by caller */
+        rcu_assign_pointer(br->ip4_querier.port, port);
+
+        return true;
+}
+
+#if IS_ENABLED(CONFIG_IPV6)
+static bool br_ip6_multicast_select_querier(struct net_bridge *br,
+                                            struct net_bridge_port *port,
+                                            struct in6_addr *saddr)
+{
+        if (!timer_pending(&br->ip6_own_query.timer) &&
+            !timer_pending(&br->ip6_other_query.timer))
+                goto update;
+
+        if (ipv6_addr_cmp(saddr, &br->ip6_querier.addr.u.ip6) <= 0)
+                goto update;
+
+        return false;
+
+update:
+        br->ip6_querier.addr.u.ip6 = *saddr;
+
+        /* update protected by general multicast_lock by caller */
+        rcu_assign_pointer(br->ip6_querier.port, port);
+
+        return true;
+}
+#endif
+
+static bool br_multicast_select_querier(struct net_bridge *br,
+                                        struct net_bridge_port *port,
+                                        struct br_ip *saddr)
+{
+        switch (saddr->proto) {
+        case htons(ETH_P_IP):
+                return br_ip4_multicast_select_querier(br, port, saddr->u.ip4);
+#if IS_ENABLED(CONFIG_IPV6)
+        case htons(ETH_P_IPV6):
+                return br_ip6_multicast_select_querier(br, port, &saddr->u.ip6);
+#endif
+        }
+
+        return false;
+}
+
 static void
-br_multicast_update_querier_timer(struct net_bridge *br,
-                                  struct bridge_mcast_querier *querier,
-                                  unsigned long max_delay)
+br_multicast_update_query_timer(struct net_bridge *br,
+                                struct bridge_mcast_other_query *query,
+                                unsigned long max_delay)
 {
-        if (!timer_pending(&querier->timer))
-                querier->delay_time = jiffies + max_delay;
+        if (!timer_pending(&query->timer))
+                query->delay_time = jiffies + max_delay;
 
-        mod_timer(&querier->timer, jiffies + br->multicast_querier_interval);
+        mod_timer(&query->timer, jiffies + br->multicast_querier_interval);
 }
 
 /*
@@ -1125,16 +1206,14 @@ timer:
 
 static void br_multicast_query_received(struct net_bridge *br,
                                         struct net_bridge_port *port,
-                                        struct bridge_mcast_querier *querier,
-                                        int saddr,
-                                        bool is_general_query,
+                                        struct bridge_mcast_other_query *query,
+                                        struct br_ip *saddr,
                                         unsigned long max_delay)
 {
-        if (saddr && is_general_query)
-                br_multicast_update_querier_timer(br, querier, max_delay);
-        else if (timer_pending(&querier->timer))
+        if (!br_multicast_select_querier(br, port, saddr))
                 return;
 
+        br_multicast_update_query_timer(br, query, max_delay);
         br_multicast_mark_router(br, port);
 }
 
@@ -1149,6 +1228,7 @@ static int br_ip4_multicast_query(struct net_bridge *br,
         struct igmpv3_query *ih3;
         struct net_bridge_port_group *p;
         struct net_bridge_port_group __rcu **pp;
+        struct br_ip saddr;
         unsigned long max_delay;
         unsigned long now = jiffies;
         __be32 group;
@@ -1190,11 +1270,14 @@ static int br_ip4_multicast_query(struct net_bridge *br,
                 goto out;
         }
 
-        br_multicast_query_received(br, port, &br->ip4_querier, !!iph->saddr,
-                                    !group, max_delay);
+        if (!group) {
+                saddr.proto = htons(ETH_P_IP);
+                saddr.u.ip4 = iph->saddr;
 
-        if (!group)
+                br_multicast_query_received(br, port, &br->ip4_other_query,
+                                            &saddr, max_delay);
                 goto out;
+        }
 
         mp = br_mdb_ip4_get(mlock_dereference(br->mdb, br), group, vid);
         if (!mp)
@@ -1234,6 +1317,7 @@ static int br_ip6_multicast_query(struct net_bridge *br,
         struct mld2_query *mld2q;
         struct net_bridge_port_group *p;
         struct net_bridge_port_group __rcu **pp;
+        struct br_ip saddr;
         unsigned long max_delay;
         unsigned long now = jiffies;
         const struct in6_addr *group = NULL;
@@ -1282,12 +1366,14 @@ static int br_ip6_multicast_query(struct net_bridge *br,
                 goto out;
         }
 
-        br_multicast_query_received(br, port, &br->ip6_querier,
-                                    !ipv6_addr_any(&ip6h->saddr),
-                                    is_general_query, max_delay);
+        if (is_general_query) {
+                saddr.proto = htons(ETH_P_IPV6);
+                saddr.u.ip6 = ip6h->saddr;
 
-        if (!group)
+                br_multicast_query_received(br, port, &br->ip6_other_query,
+                                            &saddr, max_delay);
                 goto out;
+        }
 
         mp = br_mdb_ip6_get(mlock_dereference(br->mdb, br), group, vid);
         if (!mp)
@@ -1315,11 +1401,12 @@ out:
 }
 #endif
 
-static void br_multicast_leave_group(struct net_bridge *br,
-                                     struct net_bridge_port *port,
-                                     struct br_ip *group,
-                                     struct bridge_mcast_querier *querier,
-                                     struct bridge_mcast_query *query)
+static void
+br_multicast_leave_group(struct net_bridge *br,
+                         struct net_bridge_port *port,
+                         struct br_ip *group,
+                         struct bridge_mcast_other_query *other_query,
+                         struct bridge_mcast_own_query *own_query)
 {
         struct net_bridge_mdb_htable *mdb;
         struct net_bridge_mdb_entry *mp;
@@ -1330,7 +1417,7 @@ static void br_multicast_leave_group(struct net_bridge *br,
         spin_lock(&br->multicast_lock);
         if (!netif_running(br->dev) ||
             (port && port->state == BR_STATE_DISABLED) ||
-            timer_pending(&querier->timer))
+            timer_pending(&other_query->timer))
                 goto out;
 
         mdb = mlock_dereference(br->mdb, br);
@@ -1344,7 +1431,7 @@ static void br_multicast_leave_group(struct net_bridge *br,
                 time = jiffies + br->multicast_last_member_count *
                                  br->multicast_last_member_interval;
 
-                mod_timer(&query->timer, time);
+                mod_timer(&own_query->timer, time);
 
                 for (p = mlock_dereference(mp->ports, br);
                      p != NULL;
@@ -1425,17 +1512,19 @@ static void br_ip4_multicast_leave_group(struct net_bridge *br,
                                          __u16 vid)
 {
         struct br_ip br_group;
-        struct bridge_mcast_query *query = port ? &port->ip4_query :
-                                                  &br->ip4_query;
+        struct bridge_mcast_own_query *own_query;
 
         if (ipv4_is_local_multicast(group))
                 return;
 
+        own_query = port ? &port->ip4_own_query : &br->ip4_own_query;
+
         br_group.u.ip4 = group;
         br_group.proto = htons(ETH_P_IP);
         br_group.vid = vid;
 
-        br_multicast_leave_group(br, port, &br_group, &br->ip4_querier, query);
+        br_multicast_leave_group(br, port, &br_group, &br->ip4_other_query,
+                                 own_query);
 }
 
 #if IS_ENABLED(CONFIG_IPV6)
@@ -1445,18 +1534,19 @@ static void br_ip6_multicast_leave_group(struct net_bridge *br,
                                          __u16 vid)
 {
         struct br_ip br_group;
-        struct bridge_mcast_query *query = port ? &port->ip6_query :
-                                                  &br->ip6_query;
-
+        struct bridge_mcast_own_query *own_query;
 
         if (ipv6_addr_is_ll_all_nodes(group))
                 return;
 
+        own_query = port ? &port->ip6_own_query : &br->ip6_own_query;
+
         br_group.u.ip6 = *group;
         br_group.proto = htons(ETH_P_IPV6);
         br_group.vid = vid;
 
-        br_multicast_leave_group(br, port, &br_group, &br->ip6_querier, query);
+        br_multicast_leave_group(br, port, &br_group, &br->ip6_other_query,
+                                 own_query);
 }
 #endif
 
@@ -1723,12 +1813,14 @@ int br_multicast_rcv(struct net_bridge *br, struct net_bridge_port *port,
 }
 
 static void br_multicast_query_expired(struct net_bridge *br,
-                                       struct bridge_mcast_query *query)
+                                       struct bridge_mcast_own_query *query,
+                                       struct bridge_mcast_querier *querier)
 {
         spin_lock(&br->multicast_lock);
         if (query->startup_sent < br->multicast_startup_query_count)
                 query->startup_sent++;
 
+        rcu_assign_pointer(querier, NULL);
         br_multicast_send_query(br, NULL, query);
         spin_unlock(&br->multicast_lock);
 }
@@ -1737,7 +1829,7 @@ static void br_ip4_multicast_query_expired(unsigned long data)
 {
         struct net_bridge *br = (void *)data;
 
-        br_multicast_query_expired(br, &br->ip4_query);
+        br_multicast_query_expired(br, &br->ip4_own_query, &br->ip4_querier);
 }
 
 #if IS_ENABLED(CONFIG_IPV6)
@@ -1745,7 +1837,7 @@ static void br_ip6_multicast_query_expired(unsigned long data)
 {
         struct net_bridge *br = (void *)data;
 
-        br_multicast_query_expired(br, &br->ip6_query);
+        br_multicast_query_expired(br, &br->ip6_own_query, &br->ip6_querier);
 }
 #endif
 
@@ -1767,28 +1859,30 @@ void br_multicast_init(struct net_bridge *br)
         br->multicast_querier_interval = 255 * HZ;
         br->multicast_membership_interval = 260 * HZ;
 
-        br->ip4_querier.delay_time = 0;
+        br->ip4_other_query.delay_time = 0;
+        br->ip4_querier.port = NULL;
 #if IS_ENABLED(CONFIG_IPV6)
-        br->ip6_querier.delay_time = 0;
+        br->ip6_other_query.delay_time = 0;
+        br->ip6_querier.port = NULL;
 #endif
 
         spin_lock_init(&br->multicast_lock);
         setup_timer(&br->multicast_router_timer,
                     br_multicast_local_router_expired, 0);
-        setup_timer(&br->ip4_querier.timer, br_ip4_multicast_querier_expired,
-                    (unsigned long)br);
-        setup_timer(&br->ip4_query.timer, br_ip4_multicast_query_expired,
+        setup_timer(&br->ip4_other_query.timer,
+                    br_ip4_multicast_querier_expired, (unsigned long)br);
+        setup_timer(&br->ip4_own_query.timer, br_ip4_multicast_query_expired,
                     (unsigned long)br);
 #if IS_ENABLED(CONFIG_IPV6)
-        setup_timer(&br->ip6_querier.timer, br_ip6_multicast_querier_expired,
-                    (unsigned long)br);
-        setup_timer(&br->ip6_query.timer, br_ip6_multicast_query_expired,
+        setup_timer(&br->ip6_other_query.timer,
+                    br_ip6_multicast_querier_expired, (unsigned long)br);
+        setup_timer(&br->ip6_own_query.timer, br_ip6_multicast_query_expired,
                     (unsigned long)br);
 #endif
 }
 
 static void __br_multicast_open(struct net_bridge *br,
-                                struct bridge_mcast_query *query)
+                                struct bridge_mcast_own_query *query)
 {
         query->startup_sent = 0;
 
@@ -1800,9 +1894,9 @@ static void __br_multicast_open(struct net_bridge *br,
 
 void br_multicast_open(struct net_bridge *br)
 {
-        __br_multicast_open(br, &br->ip4_query);
+        __br_multicast_open(br, &br->ip4_own_query);
 #if IS_ENABLED(CONFIG_IPV6)
-        __br_multicast_open(br, &br->ip6_query);
+        __br_multicast_open(br, &br->ip6_own_query);
 #endif
 }
 
@@ -1815,11 +1909,11 @@ void br_multicast_stop(struct net_bridge *br)
         int i;
 
         del_timer_sync(&br->multicast_router_timer);
-        del_timer_sync(&br->ip4_querier.timer);
-        del_timer_sync(&br->ip4_query.timer);
+        del_timer_sync(&br->ip4_other_query.timer);
+        del_timer_sync(&br->ip4_own_query.timer);
 #if IS_ENABLED(CONFIG_IPV6)
-        del_timer_sync(&br->ip6_querier.timer);
-        del_timer_sync(&br->ip6_query.timer);
+        del_timer_sync(&br->ip6_other_query.timer);
+        del_timer_sync(&br->ip6_own_query.timer);
 #endif
 
         spin_lock_bh(&br->multicast_lock);
@@ -1923,7 +2017,7 @@ unlock:
 }
 
 static void br_multicast_start_querier(struct net_bridge *br,
-                                       struct bridge_mcast_query *query)
+                                       struct bridge_mcast_own_query *query)
 {
         struct net_bridge_port *port;
 
@@ -1934,11 +2028,11 @@ static void br_multicast_start_querier(struct net_bridge *br,
                     port->state == BR_STATE_BLOCKING)
                         continue;
 
-                if (query == &br->ip4_query)
-                        br_multicast_enable(&port->ip4_query);
+                if (query == &br->ip4_own_query)
+                        br_multicast_enable(&port->ip4_own_query);
 #if IS_ENABLED(CONFIG_IPV6)
                 else
-                        br_multicast_enable(&port->ip6_query);
+                        br_multicast_enable(&port->ip6_own_query);
 #endif
         }
 }
@@ -1974,9 +2068,9 @@ rollback:
                         goto rollback;
         }
 
-        br_multicast_start_querier(br, &br->ip4_query);
+        br_multicast_start_querier(br, &br->ip4_own_query);
 #if IS_ENABLED(CONFIG_IPV6)
-        br_multicast_start_querier(br, &br->ip6_query);
+        br_multicast_start_querier(br, &br->ip6_own_query);
 #endif
 
 unlock:
@@ -2001,16 +2095,16 @@ int br_multicast_set_querier(struct net_bridge *br, unsigned long val)
 
         max_delay = br->multicast_query_response_interval;
 
-        if (!timer_pending(&br->ip4_querier.timer))
-                br->ip4_querier.delay_time = jiffies + max_delay;
+        if (!timer_pending(&br->ip4_other_query.timer))
+                br->ip4_other_query.delay_time = jiffies + max_delay;
 
-        br_multicast_start_querier(br, &br->ip4_query);
+        br_multicast_start_querier(br, &br->ip4_own_query);
 
 #if IS_ENABLED(CONFIG_IPV6)
-        if (!timer_pending(&br->ip6_querier.timer))
-                br->ip6_querier.delay_time = jiffies + max_delay;
+        if (!timer_pending(&br->ip6_other_query.timer))
+                br->ip6_other_query.delay_time = jiffies + max_delay;
 
-        br_multicast_start_querier(br, &br->ip6_query);
+        br_multicast_start_querier(br, &br->ip6_own_query);
 #endif
 
 unlock:
@@ -2061,3 +2155,107 @@ unlock:
 
         return err;
 }
+
+/**
+ * br_multicast_list_adjacent - Returns snooped multicast addresses
+ * @dev:        The bridge port adjacent to which to retrieve addresses
+ * @br_ip_list: The list to store found, snooped multicast IP addresses in
+ *
+ * Creates a list of IP addresses (struct br_ip_list) sensed by the multicast
+ * snooping feature on all bridge ports of dev's bridge device, excluding
+ * the addresses from dev itself.
+ *
+ * Returns the number of items added to br_ip_list.
+ *
+ * Notes:
+ * - br_ip_list needs to be initialized by caller
+ * - br_ip_list might contain duplicates in the end
+ *   (needs to be taken care of by caller)
+ * - br_ip_list needs to be freed by caller
+ */
+int br_multicast_list_adjacent(struct net_device *dev,
+                               struct list_head *br_ip_list)
+{
+        struct net_bridge *br;
+        struct net_bridge_port *port;
+        struct net_bridge_port_group *group;
+        struct br_ip_list *entry;
+        int count = 0;
+
+        rcu_read_lock();
+        if (!br_ip_list || !br_port_exists(dev))
+                goto unlock;
+
+        port = br_port_get_rcu(dev);
+        if (!port || !port->br)
+                goto unlock;
+
+        br = port->br;
+
+        list_for_each_entry_rcu(port, &br->port_list, list) {
+                if (!port->dev || port->dev == dev)
+                        continue;
+
+                hlist_for_each_entry_rcu(group, &port->mglist, mglist) {
+                        entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
+                        if (!entry)
+                                goto unlock;
+
+                        entry->addr = group->addr;
+                        list_add(&entry->list, br_ip_list);
+                        count++;
+                }
+        }
+
+unlock:
+        rcu_read_unlock();
+        return count;
+}
+EXPORT_SYMBOL_GPL(br_multicast_list_adjacent);
+
+/**
+ * br_multicast_has_querier_adjacent - Checks for a querier behind a bridge port
+ * @dev: The bridge port adjacent to which to check for a querier
+ * @proto: The protocol family to check for: IGMP -> ETH_P_IP, MLD -> ETH_P_IPV6
+ *
+ * Checks whether the given interface has a bridge on top and if so returns
+ * true if a selected querier is behind one of the other ports of this
+ * bridge. Otherwise returns false.
+ */
+bool br_multicast_has_querier_adjacent(struct net_device *dev, int proto)
+{
+        struct net_bridge *br;
+        struct net_bridge_port *port;
+        bool ret = false;
+
+        rcu_read_lock();
+        if (!br_port_exists(dev))
+                goto unlock;
+
+        port = br_port_get_rcu(dev);
+        if (!port || !port->br)
+                goto unlock;
+
+        br = port->br;
+
+        switch (proto) {
+        case ETH_P_IP:
+                if (!timer_pending(&br->ip4_other_query.timer) ||
+                    rcu_dereference(br->ip4_querier.port) == port)
+                        goto unlock;
+                break;
+        case ETH_P_IPV6:
+                if (!timer_pending(&br->ip6_other_query.timer) ||
+                    rcu_dereference(br->ip6_querier.port) == port)
+                        goto unlock;
+                break;
+        default:
+                goto unlock;
+        }
+
+        ret = true;
+unlock:
+        rcu_read_unlock();
+        return ret;
+}
+EXPORT_SYMBOL_GPL(br_multicast_has_querier_adjacent);
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index bc17210d4c52..8346e9504cdb 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -54,30 +54,24 @@ struct mac_addr
         unsigned char   addr[ETH_ALEN];
 };
 
-struct br_ip
-{
-        union {
-                __be32  ip4;
-#if IS_ENABLED(CONFIG_IPV6)
-                struct in6_addr ip6;
-#endif
-        } u;
-        __be16          proto;
-        __u16           vid;
-};
-
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 /* our own querier */
-struct bridge_mcast_query {
+struct bridge_mcast_own_query {
         struct timer_list       timer;
         u32                     startup_sent;
 };
 
 /* other querier */
-struct bridge_mcast_querier {
+struct bridge_mcast_other_query {
         struct timer_list               timer;
         unsigned long                   delay_time;
 };
+
+/* selected querier */
+struct bridge_mcast_querier {
+        struct br_ip addr;
+        struct net_bridge_port __rcu    *port;
+};
 #endif
 
 struct net_port_vlans {
@@ -178,9 +172,9 @@ struct net_bridge_port
 #define BR_PROMISC              0x00000080
 
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
-        struct bridge_mcast_query       ip4_query;
+        struct bridge_mcast_own_query   ip4_own_query;
 #if IS_ENABLED(CONFIG_IPV6)
-        struct bridge_mcast_query       ip6_query;
+        struct bridge_mcast_own_query   ip6_own_query;
 #endif /* IS_ENABLED(CONFIG_IPV6) */
         unsigned char                   multicast_router;
         struct timer_list               multicast_router_timer;
@@ -282,11 +276,13 @@ struct net_bridge
         struct hlist_head               router_list;
 
         struct timer_list               multicast_router_timer;
+        struct bridge_mcast_other_query ip4_other_query;
+        struct bridge_mcast_own_query   ip4_own_query;
         struct bridge_mcast_querier     ip4_querier;
-        struct bridge_mcast_query       ip4_query;
 #if IS_ENABLED(CONFIG_IPV6)
+        struct bridge_mcast_other_query ip6_other_query;
+        struct bridge_mcast_own_query   ip6_own_query;
         struct bridge_mcast_querier     ip6_querier;
-        struct bridge_mcast_query       ip6_query;
 #endif /* IS_ENABLED(CONFIG_IPV6) */
 #endif
 
@@ -493,7 +489,7 @@ static inline bool br_multicast_is_router(struct net_bridge *br)
 
 static inline bool
 __br_multicast_querier_exists(struct net_bridge *br,
-                              struct bridge_mcast_querier *querier)
+                              struct bridge_mcast_other_query *querier)
 {
         return time_is_before_jiffies(querier->delay_time) &&
                (br->multicast_querier || timer_pending(&querier->timer));
@@ -504,10 +500,10 @@ static inline bool br_multicast_querier_exists(struct net_bridge *br,
 {
         switch (eth->h_proto) {
         case (htons(ETH_P_IP)):
-                return __br_multicast_querier_exists(br, &br->ip4_querier);
+                return __br_multicast_querier_exists(br, &br->ip4_other_query);
 #if IS_ENABLED(CONFIG_IPV6)
         case (htons(ETH_P_IPV6)):
-                return __br_multicast_querier_exists(br, &br->ip6_querier);
+                return __br_multicast_querier_exists(br, &br->ip6_other_query);
 #endif
         default:
                 return false;