Re: [PATCH v2] bonding: Add vlan tx offload to hw_enc_features

[David Miller]

From: YueHaibing <yuehaibing@xxxxxxxxxx>
Date: Wed, 7 Aug 2019 10:19:59 +0800

> As commit 30d8177e8ac7 ("bonding: Always enable vlan tx offload")
> said, we should always enable bonding's vlan tx offload, pass the
> vlan packets to the slave devices with vlan tci, let them to handle
> vlan implementation.
> 
> Now if encapsulation protocols like VXLAN is used, skb->encapsulation
> may be set, then the packet is passed to vlan device which based on
> bonding device. However in netif_skb_features(), the check of
> hw_enc_features:
> 
> 	 if (skb->encapsulation)
>                  features &= dev->hw_enc_features;
> 
> clears NETIF_F_HW_VLAN_CTAG_TX/NETIF_F_HW_VLAN_STAG_TX. This results
> in same issue in commit 30d8177e8ac7 like this:
> 
> vlan_dev_hard_start_xmit
>   -->dev_queue_xmit
>     -->validate_xmit_skb
>       -->netif_skb_features //NETIF_F_HW_VLAN_CTAG_TX is cleared
>       -->validate_xmit_vlan
>         -->__vlan_hwaccel_push_inside //skb->tci is cleared
> ...
>  --> bond_start_xmit
>    --> bond_xmit_hash //BOND_XMIT_POLICY_ENCAP34
>      --> __skb_flow_dissect // nhoff point to IP header
>         -->  case htons(ETH_P_8021Q)
>              // skb_vlan_tag_present is false, so
>              vlan = __skb_header_pointer(skb, nhoff, sizeof(_vlan),
>              //vlan point to ip header wrongly
> 
> Fixes: b2a103e6d0af ("bonding: convert to ndo_fix_features")
> Signed-off-by: YueHaibing <yuehaibing@xxxxxxxxxx>
> Acked-by: Jay Vosburgh <jay.vosburgh@xxxxxxxxxxxxx>

Applied and queued up for -stable.