bridge: add sysfs hook to flush forwarding table

The RSTP daemon needs to be able to flush all dynamic forwarding
entries in the case of topology change.

This is a temporary interface. It will change to a netlink interface
before RSTP daemon is officially released.
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>

net/bridge/br_fdb.c

@@ -135,7 +135,26 @@ void br_fdb_cleanup(unsigned long _data)
 	mod_timer(&br->gc_timer, jiffies + HZ/10);
 }
 
+/* Completely flush all dynamic entries in forwarding database.*/
+void br_fdb_flush(struct net_bridge *br)
+{
+	int i;
 
+	spin_lock_bh(&br->hash_lock);
+	for (i = 0; i < BR_HASH_SIZE; i++) {
+		struct net_bridge_fdb_entry *f;
+		struct hlist_node *h, *n;
+		hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
+			if (!f->is_static)
+				fdb_delete(f);
+		}
+	}
+	spin_unlock_bh(&br->hash_lock);
+}
+
+/* Flush all entries refering to a specific port.
+ * if do_all is set also flush static entries
+ */
 void br_fdb_delete_by_port(struct net_bridge *br,
 			   const struct net_bridge_port *p,
 			   int do_all)

net/bridge/br_private.h

@@ -135,6 +135,7 @@ extern int br_dev_xmit(struct sk_buff *skb, struct net_device *dev);
 /* br_fdb.c */
 extern void br_fdb_init(void);
 extern void br_fdb_fini(void);
+extern void br_fdb_flush(struct net_bridge *br);
 extern void br_fdb_changeaddr(struct net_bridge_port *p,
 			      const unsigned char *newaddr);
 extern void br_fdb_cleanup(unsigned long arg);

net/bridge/br_sysfs_br.c

@@ -309,6 +309,19 @@ static ssize_t store_group_addr(struct device *d,
 static DEVICE_ATTR(group_addr, S_IRUGO | S_IWUSR,
 		   show_group_addr, store_group_addr);
 
+static ssize_t store_flush(struct device *d,
+			   struct device_attribute *attr,
+			   const char *buf, size_t len)
+{
+	struct net_bridge *br = to_bridge(d);
+
+	if (!capable(CAP_NET_ADMIN))
+		return -EPERM;
+
+	br_fdb_flush(br);
+	return len;
+}
+static DEVICE_ATTR(flush, S_IWUSR, NULL, store_flush);
 
 static struct attribute *bridge_attrs[] = {
 	&dev_attr_forward_delay.attr,
@@ -328,6 +341,7 @@ static struct attribute *bridge_attrs[] = {
 	&dev_attr_topology_change_timer.attr,
 	&dev_attr_gc_timer.attr,
 	&dev_attr_group_addr.attr,
+	&dev_attr_flush.attr,
 	NULL
 };
 

net/bridge/br_sysfs_if.c

@@ -137,6 +137,13 @@ static ssize_t show_hold_timer(struct net_bridge_port *p,
 }
 static BRPORT_ATTR(hold_timer, S_IRUGO, show_hold_timer, NULL);
 
+static ssize_t store_flush(struct net_bridge_port *p, unsigned long v)
+{
+	br_fdb_delete_by_port(p->br, p, 0); // Don't delete local entry
+	return 0;
+}
+static BRPORT_ATTR(flush, S_IWUSR, NULL, store_flush);
+
 static struct brport_attribute *brport_attrs[] = {
 	&brport_attr_path_cost,
 	&brport_attr_priority,
@@ -152,6 +159,7 @@ static struct brport_attribute *brport_attrs[] = {
 	&brport_attr_message_age_timer,
 	&brport_attr_forward_delay_timer,
 	&brport_attr_hold_timer,
+	&brport_attr_flush,
 	NULL
 };