[PATCH 3.11 116/138] Revert "macvlan : fix checksums error when we are in bridge mode"

[Luis Henriques]

3.11.10.11 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Vlad Yasevich <vyasevic at redhat.com>

commit f114890cdf84d753f6b41cd0cc44ba51d16313da upstream.

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 at free.fr>
CC: Patrick McHardy <kaber at trash.net>
CC: Andrian Nord <nightnord at gmail.com>
CC: Eric Dumazet <eric.dumazet at gmail.com>
CC: Michael S. Tsirkin <mst at redhat.com>
CC: Jason Wang <jasowang at redhat.com>
Signed-off-by: Vlad Yasevich <vyasevic at redhat.com>
Acked-by: Michael S. Tsirkin <mst at redhat.com>
Acked-by: Jason Wang <jasowang at redhat.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/net/macvlan.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index 16b43bf544b7..9f7dd0ce4c70 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -261,11 +261,9 @@ 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)) {
@@ -283,7 +281,6 @@ 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);
 }
-- 
1.9.1