Subject: [PATCH] bridge: fix hang on removal of bridge via netlink

From: Stephen Hemminger <[email-masked]>
Date: Thu, 6 Oct 2011 14:19:41 -0700

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 <[email-masked]>
Signed-off-by: Stephen Hemminger <[email-masked]>

---
Patch is against net-next but should go to net and stable trees
since it is an observable hang on 3.0 and later kernels.

--- a/net/bridge/br_if.c	2011-10-03 11:08:36.304168386 -0700
+++ b/net/bridge/br_if.c	2011-10-06 11:27:47.682488755 -0700
@@ -160,9 +160,10 @@ static void del_nbp(struct net_bridge_po
 	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) {
@@ -267,7 +268,7 @@ int br_del_bridge(struct net *net, const
 	}
 
 	else
-		del_br(netdev_priv(dev), NULL);
+		br_dev_delete(dev, NULL);
 
 	rtnl_unlock();
 	return ret;
@@ -446,7 +447,7 @@ void __net_exit br_net_exit(struct 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();
--- a/net/bridge/br_netlink.c	2011-09-16 13:12:58.061369744 -0700
+++ b/net/bridge/br_netlink.c	2011-10-06 11:20:21.808911679 -0700
@@ -210,6 +210,7 @@ static struct rtnl_link_ops br_link_ops
 	.priv_size	= sizeof(struct net_bridge),
 	.setup		= br_dev_setup,
 	.validate	= br_validate,
+	.dellink	= br_dev_delete,
 };
 
 int __init br_netlink_init(void)
--- a/net/bridge/br_private.h	2011-10-06 08:42:27.353044954 -0700
+++ b/net/bridge/br_private.h	2011-10-06 11:25:17.845118817 -0700
@@ -301,6 +301,7 @@ static inline int br_is_root_bridge(cons
 
 /* 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