bridge: Add a flag to control unicast packet flood.

Add a flag to control flood of unicast traffic.  By default, flood is
on and the bridge will flood unicast traffic if it doesn't know
the destination.  When the flag is turned off, unicast traffic
without an FDB will not be forwarded to the specified port.

Signed-off-by: Vlad Yasevich <vyasevic@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
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 707f362..2a2cdb7 100644
--- a/net/bridge/br_sysfs_if.c
+++ b/net/bridge/br_sysfs_if.c
@@ -159,6 +159,7 @@
 BRPORT_ATTR_FLAG(bpdu_guard, BR_BPDU_GUARD);
 BRPORT_ATTR_FLAG(root_block, BR_ROOT_BLOCK);
 BRPORT_ATTR_FLAG(learning, BR_LEARNING);
+BRPORT_ATTR_FLAG(unicast_flood, BR_FLOOD);
 
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 static ssize_t show_multicast_router(struct net_bridge_port *p, char *buf)
@@ -197,6 +198,7 @@
 	&brport_attr_bpdu_guard,
 	&brport_attr_root_block,
 	&brport_attr_learning,
+	&brport_attr_unicast_flood,
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 	&brport_attr_multicast_router,
 	&brport_attr_multicast_fast_leave,