vlan: more careful checksum features handling
When combining real_dev's features and vlan_features, simple
bitwise AND is used. This doesn't work well for checksum
offloading features as if one set has NETIF_F_HW_CSUM and the
other NETIF_F_IP_CSUM and/or NETIF_F_IPV6_CSUM, we end up with
no checksum offloading. However, from the logical point of view
(how can_checksum_protocol() works), NETIF_F_HW_CSUM contains
the functionality of NETIF_F_IP_CSUM and NETIF_F_IPV6_CSUM so
that the result should be IP/IPV6.
Add helper function netdev_intersect_features() implementing
this logic and use it in vlan_dev_fix_features().
Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
index 8f025af..4181fb7 100644
--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c
@@ -678,9 +678,9 @@
struct net_device *real_dev = vlan_dev_priv(dev)->real_dev;
netdev_features_t old_features = features;
- features &= real_dev->vlan_features;
+ features = netdev_intersect_features(features, real_dev->vlan_features);
features |= NETIF_F_RXCSUM;
- features &= real_dev->features;
+ features = netdev_intersect_features(features, real_dev->features);
features |= old_features & NETIF_F_SOFT_FEATURES;
features |= NETIF_F_LLTX;