bonding: register slave pointer for rx_handler

Register slave pointer as rx_handler data. That would eventually prevent
need to loop over slave devices to find the right slave.

Use synchronize_net to ensure that bond_handle_frame does not get slave
structure freed when working with that.

Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Reviewed-by: Nicolas de Pesloüan <nicolas.2p.debian@free.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bonding/bond_main.c

@@ -1482,21 +1482,22 @@ static bool bond_should_deliver_exact_match(struct sk_buff *skb,
 
 static struct sk_buff *bond_handle_frame(struct sk_buff *skb)
 {
-	struct net_device *slave_dev;
+	struct slave *slave;
 	struct net_device *bond_dev;
 
 	skb = skb_share_check(skb, GFP_ATOMIC);
 	if (unlikely(!skb))
 		return NULL;
-	slave_dev = skb->dev;
-	bond_dev = ACCESS_ONCE(slave_dev->master);
+
+	slave = bond_slave_get_rcu(skb->dev);
+	bond_dev = ACCESS_ONCE(slave->dev->master);
 	if (unlikely(!bond_dev))
 		return skb;
 
 	if (bond_dev->priv_flags & IFF_MASTER_ARPMON)
-		slave_dev->last_rx = jiffies;
+		slave->dev->last_rx = jiffies;
 
-	if (bond_should_deliver_exact_match(skb, slave_dev, bond_dev)) {
+	if (bond_should_deliver_exact_match(skb, slave->dev, bond_dev)) {
 		skb->deliver_no_wcard = 1;
 		return skb;
 	}
@@ -1694,7 +1695,8 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
 		pr_debug("Error %d calling netdev_set_bond_master\n", res);
 		goto err_restore_mac;
 	}
-	res = netdev_rx_handler_register(slave_dev, bond_handle_frame, NULL);
+	res = netdev_rx_handler_register(slave_dev, bond_handle_frame,
+					 new_slave);
 	if (res) {
 		pr_debug("Error %d calling netdev_rx_handler_register\n", res);
 		goto err_unset_master;
@@ -1916,6 +1918,7 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
 
 err_unreg_rxhandler:
 	netdev_rx_handler_unregister(slave_dev);
+	synchronize_net();
 
 err_unset_master:
 	netdev_set_bond_master(slave_dev, NULL);
@@ -2099,6 +2102,7 @@ int bond_release(struct net_device *bond_dev, struct net_device *slave_dev)
 	}
 
 	netdev_rx_handler_unregister(slave_dev);
+	synchronize_net();
 	netdev_set_bond_master(slave_dev, NULL);
 
 	slave_disable_netpoll(slave);
@@ -2213,6 +2217,7 @@ static int bond_release_all(struct net_device *bond_dev)
 		}
 
 		netdev_rx_handler_unregister(slave_dev);
+		synchronize_net();
 		netdev_set_bond_master(slave_dev, NULL);
 
 		slave_disable_netpoll(slave);

drivers/net/bonding/bonding.h

@@ -266,6 +266,9 @@ struct bonding {
 #endif /* CONFIG_DEBUG_FS */
 };
 
+#define bond_slave_get_rcu(dev) \
+	((struct slave *) rcu_dereference(dev->rx_handler_data))
+
 /**
  * Returns NULL if the net_device does not belong to any of the bond's slaves
  *