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Subject[PATCH 3.12 088/103] Revert "macvlan : fix checksums error when we are in bridge mode"
From: Vlad Yasevich <>

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


[ Upstream commit f114890cdf84d753f6b41cd0cc44ba51d16313da ]

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 <>
CC: Patrick McHardy <>
CC: Andrian Nord <>
CC: Eric Dumazet <>
CC: Michael S. Tsirkin <>
CC: Jason Wang <>
Signed-off-by: Vlad Yasevich <>
Acked-by: Michael S. Tsirkin <>
Acked-by: Jason Wang <>
Signed-off-by: David S. Miller <>
Signed-off-by: Jiri Slaby <>
drivers/net/macvlan.c | 3 ---
1 file changed, 3 deletions(-)

diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index 9bf46bd19b87..fb5f47e94547 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)

- skb->ip_summed = ip_summed;
skb->dev = vlan->lowerdev;
return dev_queue_xmit(skb);

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