bridge: Add multicast_router sysfs entries

This patch allows the user to forcibly enable/disable ports as
having multicast routers attached.  A port with a multicast router
will receive all multicast traffic.

The value 0 disables it completely.  The default is 1 which lets
the system automatically detect the presence of routers (currently
this is limited to picking up queries), and 2 means that the port
will always receive all multicast traffic.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/bridge/br_sysfs_if.c b/net/bridge/br_sysfs_if.c
index 820643a..696596c 100644
--- a/net/bridge/br_sysfs_if.c
+++ b/net/bridge/br_sysfs_if.c
@@ -159,6 +159,21 @@
 static BRPORT_ATTR(hairpin_mode, S_IRUGO | S_IWUSR,
 		   show_hairpin_mode, store_hairpin_mode);
 
+#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
+static ssize_t show_multicast_router(struct net_bridge_port *p, char *buf)
+{
+	return sprintf(buf, "%d\n", p->multicast_router);
+}
+
+static ssize_t store_multicast_router(struct net_bridge_port *p,
+				      unsigned long v)
+{
+	return br_multicast_set_port_router(p, v);
+}
+static BRPORT_ATTR(multicast_router, S_IRUGO | S_IWUSR, show_multicast_router,
+		   store_multicast_router);
+#endif
+
 static struct brport_attribute *brport_attrs[] = {
 	&brport_attr_path_cost,
 	&brport_attr_priority,
@@ -176,6 +191,9 @@
 	&brport_attr_hold_timer,
 	&brport_attr_flush,
 	&brport_attr_hairpin_mode,
+#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
+	&brport_attr_multicast_router,
+#endif
 	NULL
 };