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/include/linux/netdevice.h b/include/linux/netdevice.h
index 2dea98c..f4ad247 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3153,6 +3153,20 @@ const char *netdev_drivername(const struct net_device *dev);
 
 void linkwatch_run_queue(void);
 
+static inline netdev_features_t netdev_intersect_features(netdev_features_t f1,
+                                                         netdev_features_t f2)
+{
+       if (f1 & NETIF_F_GEN_CSUM)
+               f1 |= (NETIF_F_ALL_CSUM & ~NETIF_F_GEN_CSUM);
+       if (f2 & NETIF_F_GEN_CSUM)
+               f2 |= (NETIF_F_ALL_CSUM & ~NETIF_F_GEN_CSUM);
+       f1 &= f2;
+       if (f1 & NETIF_F_GEN_CSUM)
+               f1 &= ~(NETIF_F_ALL_CSUM & ~NETIF_F_GEN_CSUM);
+
+       return f1;
+}
+
 static inline netdev_features_t netdev_get_wanted_features(
        struct net_device *dev)
 {

diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
index 8f025af..4181fb7 100644 (file)
--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c
@@ -678,9 +678,9 @@ static netdev_features_t vlan_dev_fix_features(struct net_device *dev,
        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;