net: Allow for more then a single subclass for netif_addr_lock

Currently netif_addr_lock_nested assumes that there can be only
a single nesting level between 2 devices.  However, if we
have multiple devices of the same type stacked, this fails.
For example:
 eth0 <-- vlan0.10 <-- vlan0.10.20

A more complicated configuration may stack more then one type of
device in different order.
Ex:
  eth0 <-- vlan0.10 <-- macvlan0 <-- vlan1.10.20 <-- macvlan1

This patch adds an ndo_* function that allows each stackable
device to report its nesting level.  If the device doesn't
provide this function default subclass of 1 is used.

Signed-off-by: Vlad Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 1 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index fb912e8e5c7f..9d4b1f1b6b75 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1144,6 +1144,7 @@ struct net_device_ops {
         netdev_tx_t             (*ndo_dfwd_start_xmit) (struct sk_buff *skb,
                                                         struct net_device *dev,
                                                         void *priv);
+        int                     (*ndo_get_lock_subclass)(struct net_device *dev);
 };
 
 /**
@@ -2950,7 +2951,12 @@ static inline void netif_addr_lock(struct net_device *dev)
 
 static inline void netif_addr_lock_nested(struct net_device *dev)
 {
-        spin_lock_nested(&dev->addr_list_lock, SINGLE_DEPTH_NESTING);
+        int subclass = SINGLE_DEPTH_NESTING;
+
+        if (dev->netdev_ops->ndo_get_lock_subclass)
+                subclass = dev->netdev_ops->ndo_get_lock_subclass(dev);
+
+        spin_lock_nested(&dev->addr_list_lock, subclass);
 }
 
 static inline void netif_addr_lock_bh(struct net_device *dev)