bonding: Fix stacked device detection in arp monitoring

Prior to commit fbd929f2dce460456807a51e18d623db3db9f077
	bonding: support QinQ for bond arp interval

the arp monitoring code allowed for proper detection of devices
stacked on top of vlans.  Since the above commit, the
code can still detect a device stacked on top of single
vlan, but not a device stacked on top of Q-in-Q configuration.
The search will only set the inner vlan tag if the route
device is the vlan device.  However, this is not always the
case, as it is possible to extend the stacked configuration.

With this patch it is possible to provision devices on
top Q-in-Q vlan configuration that should be used as
a source of ARP monitoring information.

For example:
ip link add link bond0 vlan10 type vlan proto 802.1q id 10
ip link add link vlan10 vlan100 type vlan proto 802.1q id 100
ip link add link vlan100 type macvlan

Note:  This patch limites the number of stacked VLANs to 2,
just like before.  The original, however had another issue
in that if we had more then 2 levels of VLANs, we would end
up generating incorrectly tagged traffic.  This is no longer
possible.

Fixes: fbd929f2dce460456807a51e18d623db3db9f077 (bonding: support QinQ for bond arp interval)
CC: Jay Vosburgh <j.vosburgh@gmail.com>
CC: Veaceslav Falico <vfalico@redhat.com>
CC: Andy Gospodarek <andy@greyhouse.net>
CC: Ding Tianhong <dingtianhong@huawei.com>
CC: Patric McHardy <kaber@trash.net>
Signed-off-by: Vlad Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 15 insertions, 0 deletions

diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h
index 724bde8477b2..c901b13b6f03 100644
--- a/include/linux/if_vlan.h
+++ b/include/linux/if_vlan.h
@@ -484,4 +484,10 @@ static inline void vlan_set_encap_proto(struct sk_buff *skb,
                  */
                 skb->protocol = htons(ETH_P_802_2);
 }
+
+static inline int vlan_get_encap_level(struct net_device *dev)
+{
+        BUG_ON(!is_vlan_dev(dev));
+        return vlan_dev_priv(dev)->nest_level;
+}
 #endif /* !(_LINUX_IF_VLAN_H_) */
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 9d4b1f1b6b75..b42d07b0390b 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3056,10 +3056,19 @@ extern int		weight_p;
 extern int              bpf_jit_enable;
 
 bool netdev_has_upper_dev(struct net_device *dev, struct net_device *upper_dev);
+struct net_device *netdev_upper_get_next_dev_rcu(struct net_device *dev,
+                                                     struct list_head **iter);
 struct net_device *netdev_all_upper_get_next_dev_rcu(struct net_device *dev,
                                                      struct list_head **iter);
 
 /* iterate through upper list, must be called under RCU read lock */
+#define netdev_for_each_upper_dev_rcu(dev, updev, iter) \
+        for (iter = &(dev)->adj_list.upper, \
+             updev = netdev_upper_get_next_dev_rcu(dev, &(iter)); \
+             updev; \
+             updev = netdev_upper_get_next_dev_rcu(dev, &(iter)))
+
+/* iterate through upper list, must be called under RCU read lock */
 #define netdev_for_each_all_upper_dev_rcu(dev, updev, iter) \
         for (iter = &(dev)->all_adj_list.upper, \
              updev = netdev_all_upper_get_next_dev_rcu(dev, &(iter)); \