+
+/**
+ * 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);