Re: [PATCH net v2 2/3] packet: always probe for transport header

[Jason Wang <jasowang@redhat.com>]

On 11/11/2015 06:03 AM, Daniel Borkmann wrote:
> We concluded that the skb_probe_transport_header() should better be
> called unconditionally. Avoiding the call into the flow dissector has
> also not really much to do with the direct xmit mode.
>
> While it seems that only virtio_net code makes use of GSO from non
> RX/TX ring packet socket paths, we should probe for a transport header
> nevertheless before they hit devices.
>
> Reference: http://thread.gmane.org/gmane.linux.network/386173/
> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
> Cc: Jason Wang <jasowang@redhat.com>
> ---
>  net/packet/af_packet.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
> index 80c36c0..bdecf17 100644
> --- a/net/packet/af_packet.c
> +++ b/net/packet/af_packet.c
> @@ -2447,8 +2447,7 @@ static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb,
>  		len = ((to_write > len_max) ? len_max : to_write);
>  	}
>  
> -	if (!packet_use_direct_xmit(po))
> -		skb_probe_transport_header(skb, 0);
> +	skb_probe_transport_header(skb, 0);
>  
>  	return tp_len;
>  }
> @@ -2808,8 +2807,8 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
>  		len += vnet_hdr_len;
>  	}
>  
> -	if (!packet_use_direct_xmit(po))
> -		skb_probe_transport_header(skb, reserve);
> +	skb_probe_transport_header(skb, reserve);
> +
>  	if (unlikely(extra_len == 4))
>  		skb->no_fcs = 1;
>  

Acked-by: Jason Wang <jasowang@redhat.com>