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

[Peter Staubach]

Arjan van de Ven wrote:

> On Thu, 2006-06-15 at 16:40 +0200, deweerdt@xxxxxxx 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@xxxxxxxxxxxxxxx>
> Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
> ---
> 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;

Shouldn't this test for new_dev being NULL _before_ it gets used?

   Thanx...

      ps
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