[patch] lockdep annotate vlan net device as being a special class

[Arjan van de Ven <arjan@linux.intel.com>]

On Thu, 2006-06-15 at 16:40 +0200, deweerdt@free.fr wrote:
> Hi,
> 
> Assigning an inet address to a vlanized interface triggered the following BUG
> from the lock validator (kernel is 2.6.17-rc6-mm2):

ok below is a real working (cross my fingers) patch against the current
-mm tree:

vlan network devices have devices nesting below it, and are a special
"super class" of normal network devices; split their locks off into a
separate class since they always nest.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 net/8021q/vlan.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

Index: linux-2.6.17-lockdep/net/8021q/vlan.c
===================================================================
--- linux-2.6.17-lockdep.orig/net/8021q/vlan.c
+++ linux-2.6.17-lockdep/net/8021q/vlan.c
@@ -364,6 +364,14 @@ static void vlan_transfer_operstate(cons
 	}
 }
 
+/*
+ * vlan network devices have devices nesting below it, and are a special
+ * "super class" of normal network devices; split their locks off into a
+ * separate class since they always nest.
+ */
+static struct lock_class_key vlan_netdev_xmit_lock_key;
+
+
 /*  Attach a VLAN device to a mac address (ie Ethernet Card).
  *  Returns the device that was created, or NULL if there was
  *  an error of some kind.
@@ -460,6 +468,8 @@ static struct net_device *register_vlan_
 		    
 	new_dev = alloc_netdev(sizeof(struct vlan_dev_info), name,
 			       vlan_setup);
+
+	lockdep_set_class(&new_dev->_xmit_lock, &vlan_netdev_xmit_lock_key);
 	if (new_dev == NULL)
 		goto out_unlock;