bridge: multicast: restore router configuration on port link down/up

When a port goes through a link down/up the multicast router configuration
is not restored.
Signed-off-by: Satish Ashok <sashok@cumulusnetworks.com>
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Fixes: 0909e117 ("bridge: Add multicast_router sysfs entries")
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_multicast.c

@@ -37,6 +37,8 @@
 
 static void br_multicast_start_querier(struct net_bridge *br,
 				       struct bridge_mcast_own_query *query);
+static void br_multicast_add_router(struct net_bridge *br,
+				    struct net_bridge_port *port);
 unsigned int br_mdb_rehash_seq;
 
 static inline int br_ip_equal(const struct br_ip *a, const struct br_ip *b)
@@ -936,6 +938,8 @@ void br_multicast_enable_port(struct net_bridge_port *port)
 #if IS_ENABLED(CONFIG_IPV6)
 	br_multicast_enable(&port->ip6_own_query);
 #endif
+	if (port->multicast_router == 2 && hlist_unhashed(&port->rlist))
+		br_multicast_add_router(br, port);
 
 out:
 	spin_unlock(&br->multicast_lock);