net: Move check for multiple vlans to drivers

To allow drivers to handle the features check for multiple tags,
move the check to ndo_features_check().
As no drivers currently handle multiple tagged TSO, introduce
dflt_features_check() and call it if the driver does not have
ndo_features_check().
Signed-off-by: NToshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c

@@ -12557,6 +12557,7 @@ static netdev_features_t bnx2x_features_check(struct sk_buff *skb,
 					      struct net_device *dev,
 					      netdev_features_t features)
 {
+	features = vlan_features_check(skb, features);
 	return vxlan_features_check(skb, features);
 }
 

drivers/net/ethernet/mellanox/mlx4/en_netdev.c

@@ -2373,6 +2373,7 @@ static netdev_features_t mlx4_en_features_check(struct sk_buff *skb,
 						struct net_device *dev,
 						netdev_features_t features)
 {
+	features = vlan_features_check(skb, features);
 	return vxlan_features_check(skb, features);
 }
 #endif

drivers/net/ethernet/qlogic/qlcnic/qlcnic_main.c

@@ -507,6 +507,7 @@ static netdev_features_t qlcnic_features_check(struct sk_buff *skb,
 					       struct net_device *dev,
 					       netdev_features_t features)
 {
+	features = vlan_features_check(skb, features);
 	return vxlan_features_check(skb, features);
 }
 #endif

include/linux/if_vlan.h

@@ -606,4 +606,26 @@ static inline bool skb_vlan_tagged_multi(const struct sk_buff *skb)
 	return true;
 }
 
+/**
+ * vlan_features_check - drop unsafe features for skb with multiple tags.
+ * @skb: skbuff to query
+ * @features: features to be checked
+ *
+ * Returns features without unsafe ones if the skb has multiple tags.
+ */
+static inline netdev_features_t vlan_features_check(const struct sk_buff *skb,
+						    netdev_features_t features)
+{
+	if (skb_vlan_tagged_multi(skb))
+		features = netdev_intersect_features(features,
+						     NETIF_F_SG |
+						     NETIF_F_HIGHDMA |
+						     NETIF_F_FRAGLIST |
+						     NETIF_F_GEN_CSUM |
+						     NETIF_F_HW_VLAN_CTAG_TX |
+						     NETIF_F_HW_VLAN_STAG_TX);
+
+	return features;
+}
+
 #endif /* !(_LINUX_IF_VLAN_H_) */

net/core/dev.c

@@ -2562,6 +2562,13 @@ static netdev_features_t harmonize_features(struct sk_buff *skb,
 	return features;
 }
 
+static netdev_features_t dflt_features_check(const struct sk_buff *skb,
+					     struct net_device *dev,
+					     netdev_features_t features)
+{
+	return vlan_features_check(skb, features);
+}
+
 netdev_features_t netif_skb_features(struct sk_buff *skb)
 {
 	struct net_device *dev = skb->dev;
@@ -2583,22 +2590,12 @@ netdev_features_t netif_skb_features(struct sk_buff *skb)
 						     dev->vlan_features |
 						     NETIF_F_HW_VLAN_CTAG_TX |
 						     NETIF_F_HW_VLAN_STAG_TX);
-	else
-		goto finalize;
 
-	if (skb_vlan_tagged_multi(skb))
-		features = netdev_intersect_features(features,
-						     NETIF_F_SG |
-						     NETIF_F_HIGHDMA |
-						     NETIF_F_FRAGLIST |
-						     NETIF_F_GEN_CSUM |
-						     NETIF_F_HW_VLAN_CTAG_TX |
-						     NETIF_F_HW_VLAN_STAG_TX);
-
-finalize:
 	if (dev->netdev_ops->ndo_features_check)
 		features &= dev->netdev_ops->ndo_features_check(skb, dev,
 								features);
+	else
+		features &= dflt_features_check(skb, dev, features);
 
 	return harmonize_features(skb, features);
 }