Subject: Re: [net-next-2.6 BUG] VLAN out of service ?

From: Stephen Hemminger <[email-masked]>
Date: Fri, 19 Dec 2008 18:18:15 -0800

On Fri, 19 Dec 2008 20:46:18 +0100
Eric Dumazet <[email-masked]> wrote:

> I just tried some VLAN settings on my machine and got an immediate crash on latest net-next-2.6
> 
> ip link set eth2 up
> 
> ip link add link eth2 eth2.825 type vlan id 825
> ip addr add 10.170.73.104/25 dev eth2.825
> ip link set eth2.825 up
> 
> ip route add 10.170.72.0/24 via 10.170.73.126
> 
> ping 10.170.73.126
> <<crash>>
> Code: Bad EIP value.
> EIP: [<00000000>] 0x0 SS:ESP 0068:f707bdb4
> Kernel panic - not syncing: Fatal exception in interrupt
> 
> crash while jumping to ops->ndo_start_xmit(skb, dev);
> 
> CONFIG_COMPAT_NET_DEV_OPS is set in my .config, eth2 is a tg3
> 
> static const struct net_device_ops vlan_netdev_ops
> has no ndo_start_xmit initializer.
> 
> Thanks
> 
> [PATCH] vlan: fix convertion to net_device_ops
> 
> commit 656299f706e52e0409733d704c2761f1b12d6954
> (vlan: convert to net_device_ops) added a net_device_ops
> with a NULL ndo_start_xmit field.
> 
> This gives a crash in dev_hard_start_xmit()
> 
> Fix it using two net_device_ops structures, one for hwaccel vlan,
> one for non hwaccel vlan.
> 
> Signed-off-by: Eric Dumazet <[email-masked]>
> ---
> diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
> index 71193a6..89a3bbd 100644
> --- a/net/8021q/vlan_dev.c
> +++ b/net/8021q/vlan_dev.c
> @@ -593,6 +593,8 @@ static const struct header_ops vlan_header_ops = {
>  	.parse	 = eth_header_parse,
>  };
>  
> +static const struct net_device_ops vlan_netdev_ops, vlan_netdev_accel_ops;
> +
>  static int vlan_dev_init(struct net_device *dev)
>  {
>  	struct net_device *real_dev = vlan_dev_info(dev)->real_dev;
> @@ -619,11 +621,11 @@ static int vlan_dev_init(struct net_device *dev)
>  	if (real_dev->features & NETIF_F_HW_VLAN_TX) {
>  		dev->header_ops      = real_dev->header_ops;
>  		dev->hard_header_len = real_dev->hard_header_len;
> -		dev->hard_start_xmit = vlan_dev_hwaccel_hard_start_xmit;
> +		dev->netdev_ops         = &vlan_netdev_accel_ops;
>  	} else {
>  		dev->header_ops      = &vlan_header_ops;
>  		dev->hard_header_len = real_dev->hard_header_len + VLAN_HLEN;
> -		dev->hard_start_xmit = vlan_dev_hard_start_xmit;
> +		dev->netdev_ops         = &vlan_netdev_ops;
>  	}
>  
>  	if (is_vlan_dev(real_dev))
> @@ -704,6 +706,22 @@ static const struct net_device_ops vlan_netdev_ops = {
>  	.ndo_uninit		= vlan_dev_uninit,
>  	.ndo_open		= vlan_dev_open,
>  	.ndo_stop		= vlan_dev_stop,
> +	.ndo_start_xmit =  vlan_dev_hard_start_xmit,
> +	.ndo_validate_addr	= eth_validate_addr,
> +	.ndo_set_mac_address	= vlan_dev_set_mac_address,
> +	.ndo_set_rx_mode	= vlan_dev_set_rx_mode,
> +	.ndo_set_multicast_list	= vlan_dev_set_rx_mode,
> +	.ndo_change_rx_flags	= vlan_dev_change_rx_flags,
> +	.ndo_do_ioctl		= vlan_dev_ioctl,
> +};
> +
> +static const struct net_device_ops vlan_netdev_accel_ops = {
> +	.ndo_change_mtu		= vlan_dev_change_mtu,
> +	.ndo_init		= vlan_dev_init,
> +	.ndo_uninit		= vlan_dev_uninit,
> +	.ndo_open		= vlan_dev_open,
> +	.ndo_stop		= vlan_dev_stop,
> +	.ndo_start_xmit =  vlan_dev_hwaccel_hard_start_xmit,
>  	.ndo_validate_addr	= eth_validate_addr,
>  	.ndo_set_mac_address	= vlan_dev_set_mac_address,
>  	.ndo_set_rx_mode	= vlan_dev_set_rx_mode,

That works (or there could just be one vlan_dev_start_xmit) that handled
both cases.