[VLAN]: nested VLAN: fix lockdep's recursive locking warning

Allow vlans nesting other vlans without lockdep's warnings (max. 2 levels
i.e. parent + child). Thanks to Patrick McHardy for pointing a bug in the
first version of this patch.

Reported-by: Benny Amorsen
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c
index 4add9bd4bc8d51c8785c65028211578e4bbe4508..032bf44eca5e4e3cbbf39b825435f1f2cb573960 100644 (file)
--- a/net/8021q/vlan.c
+++ b/net/8021q/vlan.c
@@ -323,6 +323,7 @@ static const struct header_ops vlan_header_ops = {
 static int vlan_dev_init(struct net_device *dev)
 {
        struct net_device *real_dev = VLAN_DEV_INFO(dev)->real_dev;
+       int subclass = 0;
 
        /* IFF_BROADCAST|IFF_MULTICAST; ??? */
        dev->flags  = real_dev->flags & ~IFF_UP;
@@ -349,7 +350,11 @@ static int vlan_dev_init(struct net_device *dev)
                dev->hard_start_xmit = vlan_dev_hard_start_xmit;
        }
 
-       lockdep_set_class(&dev->_xmit_lock, &vlan_netdev_xmit_lock_key);
+       if (real_dev->priv_flags & IFF_802_1Q_VLAN)
+               subclass = 1;
+
+       lockdep_set_class_and_subclass(&dev->_xmit_lock,
+                               &vlan_netdev_xmit_lock_key, subclass);
        return 0;
 }