linux-kernel - [PATCH 3.12 088/103] Revert "macvlan : fix checksums error when we are in bridge mode"

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Message-Id: <04adf0fb0c5a2d52279ff6a2215dad9187bc9890.1401371259.git.jslaby@suse.cz>
Date:	Thu, 29 May 2014 15:49:13 +0200
From:	Jiri Slaby <jslaby@...e.cz>
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Vlad Yasevich <vyasevic@...hat.com>,
	Daniel Lezcano <daniel.lezcano@...e.fr>,
	Patrick McHardy <kaber@...sh.net>,
	Andrian Nord <nightnord@...il.com>,
	Eric Dumazet <eric.dumazet@...il.com>,
	"Michael S. Tsirkin" <mst@...hat.com>,
	Jason Wang <jasowang@...hat.com>,
	"David S. Miller" <davem@...emloft.net>,
	Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 088/103] Revert "macvlan : fix checksums error when we are in bridge mode"

From: Vlad Yasevich <vyasevic@...hat.com>

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 <daniel.lezcano@...e.fr>
CC: Patrick McHardy <kaber@...sh.net>
CC: Andrian Nord <nightnord@...il.com>
CC: Eric Dumazet <eric.dumazet@...il.com>
CC: Michael S. Tsirkin <mst@...hat.com>
CC: Jason Wang <jasowang@...hat.com>
Signed-off-by: Vlad Yasevich <vyasevic@...hat.com>
Acked-by: Michael S. Tsirkin <mst@...hat.com>
Acked-by: Jason Wang <jasowang@...hat.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 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)
 	}
 
 xmit_world:
-	skb->ip_summed = ip_summed;
 	skb->dev = vlan->lowerdev;
 	return dev_queue_xmit(skb);
 }
-- 
1.9.3

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