hsr: implement dellink to clean up resources

hsr_link_ops implements ->newlink() but not ->dellink(),
which leads that resources not released after removing the device,
particularly the entries in self_node_db and node_db.

So add ->dellink() implementation to replace the priv_destructor.
This also makes the code slightly easier to understand.

Reported-by: syzbot+c6167ec3de7def23d1e8@syzkaller.appspotmail.com
Cc: Arvid Brodin <arvid.brodin@alten.se>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/hsr/hsr_device.c

@@ -344,10 +344,7 @@ static void hsr_announce(struct timer_list *t)
 	rcu_read_unlock();
 }
 
-/* According to comments in the declaration of struct net_device, this function
- * is "Called from unregister, can be used to call free_netdev". Ok then...
- */
-static void hsr_dev_destroy(struct net_device *hsr_dev)
+void hsr_dev_destroy(struct net_device *hsr_dev)
 {
 	struct hsr_priv *hsr;
 	struct hsr_port *port;
@@ -357,15 +354,16 @@ static void hsr_dev_destroy(struct net_device *hsr_dev)
 
 	hsr_debugfs_term(hsr);
 
-	rtnl_lock();
 	list_for_each_entry_safe(port, tmp, &hsr->ports, port_list)
 		hsr_del_port(port);
-	rtnl_unlock();
 
 	del_timer_sync(&hsr->prune_timer);
 	del_timer_sync(&hsr->announce_timer);
 
 	synchronize_rcu();
+
+	hsr_del_self_node(&hsr->self_node_db);
+	hsr_del_nodes(&hsr->node_db);
 }
 
 static const struct net_device_ops hsr_device_ops = {
@@ -392,7 +390,6 @@ void hsr_dev_setup(struct net_device *dev)
 	dev->priv_flags |= IFF_NO_QUEUE;
 
 	dev->needs_free_netdev = true;
-	dev->priv_destructor = hsr_dev_destroy;
 
 	dev->hw_features = NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_HIGHDMA |
 			   NETIF_F_GSO_MASK | NETIF_F_HW_CSUM |
@@ -497,7 +494,7 @@ fail:
 	list_for_each_entry_safe(port, tmp, &hsr->ports, port_list)
 		hsr_del_port(port);
 err_add_port:
-	hsr_del_node(&hsr->self_node_db);
+	hsr_del_self_node(&hsr->self_node_db);
 
 	return res;
 }

net/hsr/hsr_device.h

@@ -14,6 +14,7 @@
 void hsr_dev_setup(struct net_device *dev);
 int hsr_dev_finalize(struct net_device *hsr_dev, struct net_device *slave[2],
 		     unsigned char multicast_spec, u8 protocol_version);
+void hsr_dev_destroy(struct net_device *hsr_dev);
 void hsr_check_carrier_and_operstate(struct hsr_priv *hsr);
 bool is_hsr_master(struct net_device *dev);
 int hsr_get_max_mtu(struct hsr_priv *hsr);

net/hsr/hsr_framereg.c

@@ -104,7 +104,7 @@ int hsr_create_self_node(struct list_head *self_node_db,
 	return 0;
 }
 
-void hsr_del_node(struct list_head *self_node_db)
+void hsr_del_self_node(struct list_head *self_node_db)
 {
 	struct hsr_node *node;
 
@@ -117,6 +117,15 @@ void hsr_del_node(struct list_head *self_node_db)
 	}
 }
 
+void hsr_del_nodes(struct list_head *node_db)
+{
+	struct hsr_node *node;
+	struct hsr_node *tmp;
+
+	list_for_each_entry_safe(node, tmp, node_db, mac_list)
+		kfree(node);
+}
+
 /* Allocate an hsr_node and add it to node_db. 'addr' is the node's address_A;
  * seq_out is used to initialize filtering of outgoing duplicate frames
  * originating from the newly added node.

net/hsr/hsr_framereg.h

@@ -12,7 +12,8 @@
 
 struct hsr_node;
 
-void hsr_del_node(struct list_head *self_node_db);
+void hsr_del_self_node(struct list_head *self_node_db);
+void hsr_del_nodes(struct list_head *node_db);
 struct hsr_node *hsr_add_node(struct list_head *node_db, unsigned char addr[],
 			      u16 seq_out);
 struct hsr_node *hsr_get_node(struct hsr_port *port, struct sk_buff *skb,

net/hsr/hsr_netlink.c

@@ -69,6 +69,12 @@ static int hsr_newlink(struct net *src_net, struct net_device *dev,
 	return hsr_dev_finalize(dev, link, multicast_spec, hsr_version);
 }
 
+static void hsr_dellink(struct net_device *hsr_dev, struct list_head *head)
+{
+	hsr_dev_destroy(hsr_dev);
+	unregister_netdevice_queue(hsr_dev, head);
+}
+
 static int hsr_fill_info(struct sk_buff *skb, const struct net_device *dev)
 {
 	struct hsr_priv *hsr;
@@ -113,6 +119,7 @@ static struct rtnl_link_ops hsr_link_ops __read_mostly = {
 	.priv_size	= sizeof(struct hsr_priv),
 	.setup		= hsr_dev_setup,
 	.newlink	= hsr_newlink,
+	.dellink	= hsr_dellink,
 	.fill_info	= hsr_fill_info,
 };