bridge: Keep track of ports capable of automatic discovery.

By default, ports on the bridge are capable of automatic
discovery of nodes located behind the port. This is accomplished
via flooding of unknown traffic (BR_FLOOD) and learning the
mac addresses from these packets (BR_LEARNING).
If the above functionality is disabled by turning off these
flags, the port requires static configuration in the form
of static FDB entries to function properly.

This patch adds functionality to keep track of all ports
capable of automatic discovery. This will later be used
to control promiscuity settings.

Acked-by: Michael S. Tsirkin <[e-mail]>
Signed-off-by: Vlad Yasevich <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/bridge/br_if.c

···
 	spin_unlock_bh(&br->lock);
 }
 
+static void nbp_update_port_count(struct net_bridge *br)
+{
+	struct net_bridge_port *p;
+	u32 cnt = 0;
+
+	list_for_each_entry(p, &br->port_list, list) {
+		if (br_auto_port(p))
+			cnt++;
+	}
+	br->auto_cnt = cnt;
+}
+
 static void release_nbp(struct kobject *kobj)
 {
 	struct net_bridge_port *p
···
 	br_fdb_delete_by_port(br, p, 1);
 
 	list_del_rcu(&p->list);
+
+	nbp_update_port_count(br);
 
 	dev->priv_flags &= ~IFF_BRIDGE_PORT;
 
···
 
 	list_add_rcu(&p->list, &br->port_list);
 
+	nbp_update_port_count(br);
+
 	netdev_update_features(br->dev);
 
 	if (br->dev->needed_headroom < dev->needed_headroom)
···
 	netdev_update_features(br->dev);
 
 	return 0;
+}
+
+void br_port_flags_change(struct net_bridge_port *p, unsigned long mask)
+{
+	struct net_bridge *br = p->br;
+
+	if (mask & BR_AUTO_MASK)
+		nbp_update_port_count(br);
 }

net/bridge/br_netlink.c

···
 static int br_setport(struct net_bridge_port *p, struct nlattr *tb[])
 {
 	int err;
+	unsigned long old_flags = p->flags;
 
 	br_set_port_flag(p, tb, IFLA_BRPORT_MODE, BR_HAIRPIN_MODE);
 	br_set_port_flag(p, tb, IFLA_BRPORT_GUARD, BR_BPDU_GUARD);
···
 		if (err)
 			return err;
 	}
+
+	br_port_flags_change(p, old_flags ^ p->flags);
 	return 0;
 }
 

net/bridge/br_private.h

···
 #define BR_ADMIN_COST		0x00000010
 #define BR_LEARNING		0x00000020
 #define BR_FLOOD		0x00000040
+#define BR_AUTO_MASK (BR_FLOOD | BR_LEARNING)
 
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 	struct bridge_mcast_query	ip4_query;
···
 	struct net_port_vlans __rcu	*vlan_info;
 #endif
 };
+
+#define br_auto_port(p) ((p)->flags & BR_AUTO_MASK)
 
 #define br_port_exists(dev) (dev->priv_flags & IFF_BRIDGE_PORT)
 
···
 	struct timer_list		topology_change_timer;
 	struct timer_list		gc_timer;
 	struct kobject			*ifobj;
+	u32				auto_cnt;
 #ifdef CONFIG_BRIDGE_VLAN_FILTERING
 	u8				vlan_enabled;
 	struct net_port_vlans __rcu	*vlan_info;
···
 int br_min_mtu(const struct net_bridge *br);
 netdev_features_t br_features_recompute(struct net_bridge *br,
 					netdev_features_t features);
+void br_port_flags_change(struct net_bridge_port *port, unsigned long mask);
 
 /* br_input.c */
 int br_handle_frame_finish(struct sk_buff *skb);

net/bridge/br_sysfs_if.c

···
 static int store_flag(struct net_bridge_port *p, unsigned long v,
 		      unsigned long mask)
 {
-	unsigned long flags = p->flags;
+	unsigned long flags;
+
+	flags = p->flags;
 
 	if (v)
 		flags |= mask;
···
 
 	if (flags != p->flags) {
 		p->flags = flags;
+		br_port_flags_change(p, mask);
 		br_ifinfo_notify(RTM_NEWLINK, p);
 	}
 	return 0;