[PATCH net] r8169: fix multicast tx issue with macvlan interface

[Charles Daymand <charles.daymand@wifirst.fr>]

During kernel upgrade testing on our hardware, we found that macvlan
interface were no longer able to send valid multicast packet.

tcpdump run on our hardware was correctly showing our multicast
packet but when connecting a laptop to our hardware we didn't see any
packets.

Bisecting turned up commit 93681cd7d94f
"r8169: enable HW csum and TSO" activates the feature NETIF_F_IP_CSUM
which is responsible for the drop of packet in case of macvlan
interface. Note that revision RTL_GIGA_MAC_VER_34 was already a specific
case since TSO was keep disabled.

Deactivating NETIF_F_IP_CSUM using ethtool is correcting our multicast
issue, but we believe that this hardware issue is important enough to
keep tx checksum off by default on this revision.

The change is deactivating the default value of NETIF_F_IP_CSUM for this
specific revision.

Fixes: 93681cd7d94f ("r8169: enable HW csum and TSO")
Signed-off-by: Charles Daymand <charles.daymand@wifirst.fr>
---
 net/drivers/net/ethernet/realtek/r8169_main.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/drivers/net/ethernet/realtek/r8169_main.c b/net/drivers/net/ethernet/realtek/r8169_main.c
index a9bdafd15a35..3b69135fc500 100644
--- a/net/drivers/net/ethernet/realtek/r8169_main.c
+++ b/net/drivers/net/ethernet/realtek/r8169_main.c
@@ -5591,6 +5591,9 @@ static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 		dev->vlan_features &= ~(NETIF_F_ALL_TSO | NETIF_F_SG);
 		dev->hw_features &= ~(NETIF_F_ALL_TSO | NETIF_F_SG);
 		dev->features &= ~(NETIF_F_ALL_TSO | NETIF_F_SG);
+		if (tp->mac_version == RTL_GIGA_MAC_VER_34) {
+			dev->features &= ~NETIF_F_IP_CSUM;
+		}
 	}
 
 	dev->hw_features |= NETIF_F_RXALL;
-- 
2.20.1