bridge: mcast: add support for temporary port router

Add support for a temporary router port which doesn't depend only on the
incoming query. It can be refreshed if set to the same value, which is
a no-op for the rest.
Signed-off-by: NNikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/uapi/linux/if_bridge.h

@@ -182,6 +182,7 @@ enum {
 	MDB_RTR_TYPE_DISABLED,
 	MDB_RTR_TYPE_TEMP_QUERY,
 	MDB_RTR_TYPE_PERM,
+	MDB_RTR_TYPE_TEMP
 };
 
 enum {

net/bridge/br_multicast.c

@@ -759,13 +759,17 @@ static void br_multicast_router_expired(unsigned long data)
 	struct net_bridge *br = port->br;
 
 	spin_lock(&br->multicast_lock);
-	if (port->multicast_router != MDB_RTR_TYPE_TEMP_QUERY ||
+	if (port->multicast_router == MDB_RTR_TYPE_DISABLED ||
+	    port->multicast_router == MDB_RTR_TYPE_PERM ||
 	    timer_pending(&port->multicast_router_timer) ||
 	    hlist_unhashed(&port->rlist))
 		goto out;
 
 	hlist_del_init_rcu(&port->rlist);
 	br_rtr_notify(br->dev, port, RTM_DELMDB);
+	/* Don't allow timer refresh if the router expired */
+	if (port->multicast_router == MDB_RTR_TYPE_TEMP)
+		port->multicast_router = MDB_RTR_TYPE_TEMP_QUERY;
 
 out:
 	spin_unlock(&br->multicast_lock);
@@ -981,6 +985,9 @@ void br_multicast_disable_port(struct net_bridge_port *port)
 	if (!hlist_unhashed(&port->rlist)) {
 		hlist_del_init_rcu(&port->rlist);
 		br_rtr_notify(br->dev, port, RTM_DELMDB);
+		/* Don't allow timer refresh if disabling */
+		if (port->multicast_router == MDB_RTR_TYPE_TEMP)
+			port->multicast_router = MDB_RTR_TYPE_TEMP_QUERY;
 	}
 	del_timer(&port->multicast_router_timer);
 	del_timer(&port->ip4_own_query.timer);
@@ -1234,7 +1241,8 @@ static void br_multicast_mark_router(struct net_bridge *br,
 		return;
 	}
 
-	if (port->multicast_router != MDB_RTR_TYPE_TEMP_QUERY)
+	if (port->multicast_router == MDB_RTR_TYPE_DISABLED ||
+	    port->multicast_router == MDB_RTR_TYPE_PERM)
 		return;
 
 	br_multicast_add_router(br, port);
@@ -1850,10 +1858,15 @@ static void __del_port_router(struct net_bridge_port *p)
 int br_multicast_set_port_router(struct net_bridge_port *p, unsigned long val)
 {
 	struct net_bridge *br = p->br;
+	unsigned long now = jiffies;
 	int err = -EINVAL;
 
 	spin_lock(&br->multicast_lock);
 	if (p->multicast_router == val) {
+		/* Refresh the temp router port timer */
+		if (p->multicast_router == MDB_RTR_TYPE_TEMP)
+			mod_timer(&p->multicast_router_timer,
+				  now + br->multicast_querier_interval);
 		err = 0;
 		goto unlock;
 	}
@@ -1872,6 +1885,10 @@ int br_multicast_set_port_router(struct net_bridge_port *p, unsigned long val)
 		del_timer(&p->multicast_router_timer);
 		br_multicast_add_router(br, p);
 		break;
+	case MDB_RTR_TYPE_TEMP:
+		p->multicast_router = MDB_RTR_TYPE_TEMP;
+		br_multicast_mark_router(br, p);
+		break;
 	default:
 		goto unlock;
 	}