ACK/cmnt: [PATCH 2/2] virtio-net: restore VIRTIO_HDR_F_DATA_VALID on receiving

[Colin Ian King]

On 24/04/17 15:09, Stefan Bader wrote:
> From: Jason Wang <jasowang at redhat.com>
> 
> BugLink: http://bugs.launchpad.net/bugs/1685416
> 
> [ Upstream commit 6391a4481ba0796805d6581e42f9f0418c099e34 ]
> 
> Commit 501db511397f ("virtio: don't set VIRTIO_NET_HDR_F_DATA_VALID on
> xmit") in fact disables VIRTIO_HDR_F_DATA_VALID on receiving path too,
> fixing this by adding a hint (has_data_valid) and set it only on the
> receiving path.
> 
> Cc: Rolf Neugebauer <rolf.neugebauer at docker.com>
> Signed-off-by: Jason Wang <jasowang at redhat.com>
> Acked-by: Rolf Neugebauer <rolf.neugebauer at docker.com>
> Signed-off-by: David S. Miller <davem at davemloft.net>
> Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
> (cherry-picked from 1e7cbb413f63d8fa790c8dabc208ce2a02339c26 linux-4.9.y)
> Signed-off-by: Stefan Bader <stefan.bader at canonical.com>
> ---
>  drivers/net/macvtap.c      | 2 +-
>  drivers/net/tun.c          | 2 +-
>  drivers/net/virtio_net.c   | 2 +-
>  include/linux/virtio_net.h | 6 +++++-
>  net/packet/af_packet.c     | 2 +-
>  5 files changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
> index 070e329..b2a680f 100644
> --- a/drivers/net/macvtap.c
> +++ b/drivers/net/macvtap.c
> @@ -822,7 +822,7 @@ static ssize_t macvtap_put_user(struct macvtap_queue *q,
>  			return -EINVAL;
>  
>  		ret = virtio_net_hdr_from_skb(skb, &vnet_hdr,
> -					      macvtap_is_little_endian(q));
> +					      macvtap_is_little_endian(q), true);
>  		if (ret)
>  			BUG();
>  
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index 6f9df37..46264ed 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -1382,7 +1382,7 @@ static ssize_t tun_put_user(struct tun_struct *tun,
>  			return -EINVAL;
>  
>  		ret = virtio_net_hdr_from_skb(skb, &gso,
> -					      tun_is_little_endian(tun));
> +					      tun_is_little_endian(tun), true);
>  		if (ret) {
>  			struct skb_shared_info *sinfo = skb_shinfo(skb);
>  			pr_err("unexpected GSO type: "
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index f7717e0..5cf97fe 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -839,7 +839,7 @@ static int xmit_skb(struct send_queue *sq, struct sk_buff *skb)
>  		hdr = skb_vnet_hdr(skb);
>  
>  	if (virtio_net_hdr_from_skb(skb, &hdr->hdr,
> -				    virtio_is_little_endian(vi->vdev)))
> +				    virtio_is_little_endian(vi->vdev), false))
>  		BUG();
>  
>  	if (vi->mergeable_rx_bufs)
> diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
> index 40914bb..f211c34 100644
> --- a/include/linux/virtio_net.h
> +++ b/include/linux/virtio_net.h
> @@ -56,7 +56,8 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
>  
>  static inline int virtio_net_hdr_from_skb(const struct sk_buff *skb,
>  					  struct virtio_net_hdr *hdr,
> -					  bool little_endian)
> +					  bool little_endian,
> +					  bool has_data_valid)
>  {
>  	memset(hdr, 0, sizeof(*hdr));
>  
> @@ -91,6 +92,9 @@ static inline int virtio_net_hdr_from_skb(const struct sk_buff *skb,
>  				skb_checksum_start_offset(skb));
>  		hdr->csum_offset = __cpu_to_virtio16(little_endian,
>  				skb->csum_offset);
> +	} else if (has_data_valid &&
> +		   skb->ip_summed == CHECKSUM_UNNECESSARY) {
> +		hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
>  	} /* else everything is zero */
>  
>  	return 0;
> diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
> index e518c29..d9f28d3 100644
> --- a/net/packet/af_packet.c
> +++ b/net/packet/af_packet.c
> @@ -1972,7 +1972,7 @@ static int __packet_rcv_vnet(const struct sk_buff *skb,
>  {
>  	*vnet_hdr = (const struct virtio_net_hdr) { 0 };
>  
> -	if (virtio_net_hdr_from_skb(skb, vnet_hdr, vio_le()))
> +	if (virtio_net_hdr_from_skb(skb, vnet_hdr, vio_le(), true))
>  		BUG();
>  
>  	return 0;
> 
As long as the testing shows this works fine (as I see no testcase in
the bug report), then I'm happy with this.

Upstream cherry pick, known to fix issues on other kernels, looks sane
to me.

Acked-by: Colin Ian King <colin.king at canonical.com>