While hardware device use either NETIF_F_(IP|IPV6)_CSUM or
NETIF_F_HW_CSUM, all of the software devices use HW_CSUM.
This results in an interesting situation when the software
device is configured on top of hw device using (IP|IPV6)_CSUM.
In this situation, the user can't turn off checksum offloading
features on the software device.
This patch resolves that by adding NETIF_F_HW_CSUM to the mask
if a feature set includes only IP|IPV6 csum. This allows the user
to control the upper (software) device checksum, while at the same
time correctly propagating lower device changes up.
CC: Michal Kubecek <mkube...@suse.cz>
CC: Alexander Duyck <alexander.du...@gmail.com>
CC: Tom Herbert <t...@herbertland.com>
Signed-off-by: Vladislav Yasevich <vyase...@redhat.com>
---
V2: Addressed comments from Alex Duyck. I tested this with hacked virtio
device that set IP|IPV6 checksums instead of HW. Configuring a vlan on
top gave the vlan device with 'ip-generic: on' setting (using HW checksum).
This allows me to change vlan checksum offloads independent of virt-io nic.
Changes to virtio-nic propagated up to vlan, turning off the offloading
correctly.
include/linux/netdevice.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index b0aa089..81aed2f 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -4009,10 +4009,10 @@ static inline netdev_features_t
netdev_intersect_features(netdev_features_t f1,
netdev_features_t f2)
{
if ((f1 ^ f2) & NETIF_F_HW_CSUM) {
- if (f1 & NETIF_F_HW_CSUM)
- f1 |= (NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM);
- else
- f2 |= (NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM);
+ if (f1 & (NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM))
+ f1 |= NETIF_F_HW_CSUM;
+ if(f2 & (NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM))
+ f2 |= NETIF_F_HW_CSUM;
}
return f1 & f2;
--
2.7.4
