[v2,net,2/2] Revert "macvlan : fix checksums error when we are in bridge mode"

This reverts commit 12a2856b604476c27d85a5f9a57ae1661fc46019.
The commit above doesn't appear to be necessary any more as the
checksums appear to be correctly computed/validated.

Additionally the above commit breaks kvm configurations where
one VM is using a device that support checksum offload (virtio) and
the other VM does not.
In this case, packets leaving virtio device will have CHECKSUM_PARTIAL
set.  The packets is forwarded to a macvtap that has offload features
turned off.  Since we use CHECKSUM_UNNECESSARY, the host does does not
update the checksum and thus a bad checksum is passed up to
the guest.

CC: Daniel Lezcano <daniel.lezcano@free.fr>
CC: Patrick McHardy <kaber@trash.net>
CC: Andrian Nord <nightnord@gmail.com>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: Michael S. Tsirkin <mst@redhat.com>
CC: Jason Wang <jasowang@redhat.com>
Signed-off-by: Vlad Yasevich <vyasevic@redhat.com>
---
 drivers/net/macvlan.c | 3 ---
 1 file changed, 3 deletions(-)

On Tue, Apr 29, 2014 at 10:09:51AM -0400, Vlad Yasevich wrote:
> This reverts commit 12a2856b604476c27d85a5f9a57ae1661fc46019.
> The commit above doesn't appear to be necessary any more as the
> checksums appear to be correctly computed/validated.
> 
> Additionally the above commit breaks kvm configurations where
> one VM is using a device that support checksum offload (virtio) and
> the other VM does not.
> In this case, packets leaving virtio device will have CHECKSUM_PARTIAL
> set.  The packets is forwarded to a macvtap that has offload features
> turned off.  Since we use CHECKSUM_UNNECESSARY, the host does does not
> update the checksum and thus a bad checksum is passed up to
> the guest.
> 
> CC: Daniel Lezcano <daniel.lezcano@free.fr>
> CC: Patrick McHardy <kaber@trash.net>
> CC: Andrian Nord <nightnord@gmail.com>
> CC: Eric Dumazet <eric.dumazet@gmail.com>
> CC: Michael S. Tsirkin <mst@redhat.com>
> CC: Jason Wang <jasowang@redhat.com>
> Signed-off-by: Vlad Yasevich <vyasevic@redhat.com>

Acked-by: Michael S. Tsirkin <mst@redhat.com>

> ---
>  drivers/net/macvlan.c | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
> index 1831fb7..33b6cf8 100644
> --- a/drivers/net/macvlan.c
> +++ b/drivers/net/macvlan.c
> @@ -263,11 +263,9 @@ static int macvlan_queue_xmit(struct sk_buff *skb, struct net_device *dev)
>  	const struct macvlan_dev *vlan = netdev_priv(dev);
>  	const struct macvlan_port *port = vlan->port;
>  	const struct macvlan_dev *dest;
> -	__u8 ip_summed = skb->ip_summed;
>  
>  	if (vlan->mode == MACVLAN_MODE_BRIDGE) {
>  		const struct ethhdr *eth = (void *)skb->data;
> -		skb->ip_summed = CHECKSUM_UNNECESSARY;
>  
>  		/* send to other bridge ports directly */
>  		if (is_multicast_ether_addr(eth->h_dest)) {
> @@ -285,7 +283,6 @@ static int macvlan_queue_xmit(struct sk_buff *skb, struct net_device *dev)
>  	}
>  
>  xmit_world:
> -	skb->ip_summed = ip_summed;
>  	skb->dev = vlan->lowerdev;
>  	return dev_queue_xmit(skb);
>  }
> -- 
> 1.9.0
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On 04/29/2014 10:09 PM, Vlad Yasevich wrote:
> This reverts commit 12a2856b604476c27d85a5f9a57ae1661fc46019.
> The commit above doesn't appear to be necessary any more as the
> checksums appear to be correctly computed/validated.
>
> Additionally the above commit breaks kvm configurations where
> one VM is using a device that support checksum offload (virtio) and
> the other VM does not.
> In this case, packets leaving virtio device will have CHECKSUM_PARTIAL
> set.  The packets is forwarded to a macvtap that has offload features
> turned off.  Since we use CHECKSUM_UNNECESSARY, the host does does not
> update the checksum and thus a bad checksum is passed up to
> the guest.
>
> CC: Daniel Lezcano <daniel.lezcano@free.fr>
> CC: Patrick McHardy <kaber@trash.net>
> CC: Andrian Nord <nightnord@gmail.com>
> CC: Eric Dumazet <eric.dumazet@gmail.com>
> CC: Michael S. Tsirkin <mst@redhat.com>
> CC: Jason Wang <jasowang@redhat.com>
> Signed-off-by: Vlad Yasevich <vyasevic@redhat.com>
> ---
>  drivers/net/macvlan.c | 3 ---
>  1 file changed, 3 deletions(-)
>
> diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
> index 1831fb7..33b6cf8 100644
> --- a/drivers/net/macvlan.c
> +++ b/drivers/net/macvlan.c
> @@ -263,11 +263,9 @@ static int macvlan_queue_xmit(struct sk_buff *skb, struct net_device *dev)
>  	const struct macvlan_dev *vlan = netdev_priv(dev);
>  	const struct macvlan_port *port = vlan->port;
>  	const struct macvlan_dev *dest;
> -	__u8 ip_summed = skb->ip_summed;
>  
>  	if (vlan->mode == MACVLAN_MODE_BRIDGE) {
>  		const struct ethhdr *eth = (void *)skb->data;
> -		skb->ip_summed = CHECKSUM_UNNECESSARY;
>  
>  		/* send to other bridge ports directly */
>  		if (is_multicast_ether_addr(eth->h_dest)) {
> @@ -285,7 +283,6 @@ static int macvlan_queue_xmit(struct sk_buff *skb, struct net_device *dev)
>  	}
>  
>  xmit_world:
> -	skb->ip_summed = ip_summed;
>  	skb->dev = vlan->lowerdev;
>  	return dev_queue_xmit(skb);
>  }

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