Re: [PATCH net] vlan: Mask off vlan acceleration features on vlan device.

[Vlad Yasevich <vyasevic@redhat.com>]

On 03/26/2014 04:25 PM, Vlad Yasevich wrote:
> Some drivers incorrectly assign vlan acceleration features to
> vlan_features thus causing issues for Q-in-Q vlan configurations.
> Prevent this once and for all by masking off acceleration features
> for vlan devices until such time as we support stacked acceleration.
> 
> Signed-off-by: Vlad Yasevich <vyasevic@redhat.com>
> ---
> 
> Hi David
> 
>> This is at least the second time I've seen a fix exactly like this
>> one, it certainly therefore deserves a tree-wide audit if anyone has
>> time for that.
> 
> How about this approach instead?
> 
>  include/linux/netdev_features.h | 7 +++++++
>  net/8021q/vlan_dev.c            | 4 +++-
>  2 files changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/netdev_features.h b/include/linux/netdev_features.h
> index 1005ebf..84a4e5f 100644
> --- a/include/linux/netdev_features.h
> +++ b/include/linux/netdev_features.h
> @@ -163,4 +163,11 @@ enum {
>  /* changeable features with no special hardware requirements */
>  #define NETIF_F_SOFT_FEATURES	(NETIF_F_GSO | NETIF_F_GRO)
>  
> +#define NETIF_F_VLAN_FEATURES	(NETIF_F_HW_VLAN_CTAG_FILTER | \
> +				 NETIF_F_HW_VLAN_STAG_RX | \
> +				 NETIF_F_HW_VLAN_STAG_TX | \
> +				 NETIF_F_HW_VLAN_STAG_FILTER | \
> +				 NETIF_F_HW_VLAN_STAG_RX | \
> +				 NETIF_F_HW_VLAN_STAG_TX)
> +

sorry, cut/paste error.  Will fix.

-vlad

>  #endif	/* _LINUX_NETDEV_FEATURES_H */
> diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
> index a9591ff..d99e8df 100644
> --- a/net/8021q/vlan_dev.c
> +++ b/net/8021q/vlan_dev.c
> @@ -576,7 +576,8 @@ static int vlan_dev_init(struct net_device *dev)
>  			   NETIF_F_HIGHDMA | NETIF_F_SCTP_CSUM |
>  			   NETIF_F_ALL_FCOE;
>  
> -	dev->features |= real_dev->vlan_features | NETIF_F_LLTX;
> +	dev->features |= (real_dev->vlan_features & ~NETIF_F_VLAN_FEATURES) |
> +			 NETIF_F_LLTX;
>  	dev->gso_max_size = real_dev->gso_max_size;
>  
>  	/* ipv6 shared card related stuff */
> @@ -651,6 +652,7 @@ static netdev_features_t vlan_dev_fix_features(struct net_device *dev,
>  	features &= real_dev->features;
>  
>  	features |= old_features & NETIF_F_SOFT_FEATURES;
> +	features &= ~NETIF_F_VLAN_FEATURES;
>  	features |= NETIF_F_LLTX;
>  
>  	return features;
>