bridge: fix hang on removal of bridge via netlink

Need to cleanup bridge device timers and ports when being bridge
device is being removed via netlink.

This fixes the problem of observed when doing:
 ip link add br0 type bridge
 ip link set dev eth1 master br0
 ip link set br0 up
 ip link del br0

which would cause br0 to hang in unregister_netdev because
of leftover reference count.

Reported-by: Sridhar Samudrala <sri@us.ibm.com>
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Sridhar Samudrala <sri@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_if.c

@@ -161,9 +161,10 @@ static void del_nbp(struct net_bridge_port *p)
 	call_rcu(&p->rcu, destroy_nbp_rcu);
 }
 
-/* called with RTNL */
-static void del_br(struct net_bridge *br, struct list_head *head)
+/* Delete bridge device */
+void br_dev_delete(struct net_device *dev, struct list_head *head)
 {
+	struct net_bridge *br = netdev_priv(dev);
 	struct net_bridge_port *p, *n;
 
 	list_for_each_entry_safe(p, n, &br->port_list, list) {
@@ -268,7 +269,7 @@ int br_del_bridge(struct net *net, const char *name)
 	}
 
 	else
-		del_br(netdev_priv(dev), NULL);
+		br_dev_delete(dev, NULL);
 
 	rtnl_unlock();
 	return ret;
@@ -449,7 +450,7 @@ void __net_exit br_net_exit(struct net *net)
 	rtnl_lock();
 	for_each_netdev(net, dev)
 		if (dev->priv_flags & IFF_EBRIDGE)
-			del_br(netdev_priv(dev), &list);
+			br_dev_delete(dev, &list);
 
 	unregister_netdevice_many(&list);
 	rtnl_unlock();

net/bridge/br_netlink.c

@@ -210,6 +210,7 @@ static struct rtnl_link_ops br_link_ops __read_mostly = {
 	.priv_size	= sizeof(struct net_bridge),
 	.setup		= br_dev_setup,
 	.validate	= br_validate,
+	.dellink	= br_dev_delete,
 };
 
 int __init br_netlink_init(void)

net/bridge/br_private.h

@@ -294,6 +294,7 @@ static inline int br_is_root_bridge(const struct net_bridge *br)
 
 /* br_device.c */
 extern void br_dev_setup(struct net_device *dev);
+extern void br_dev_delete(struct net_device *dev, struct list_head *list);
 extern netdev_tx_t br_dev_xmit(struct sk_buff *skb,
 			       struct net_device *dev);
 #ifdef CONFIG_NET_POLL_CONTROLLER