net offloading: Generalize netif_get_vlan_features().

netif_get_vlan_features() is currently only used by netif_needs_gso(),
so it only concerns itself with GSO features.  However, several other
places also should take into account the contents of the packet when
deciding whether to offload to hardware.  This generalizes the function
to return features about all of the various forms of offloading.  Since
offloads tend to be linked together, this avoids duplicating the logic
in each location (i.e. the scatter/gather code also needs the checksum
logic).

Suggested-by: Michał Mirosław <mirqus@gmail.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 27 insertions, 8 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index d8befd06da0..a51dfd7b56f 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2017,22 +2017,41 @@ static inline void skb_orphan_try(struct sk_buff *skb)
 	}
 }
 
-int netif_get_vlan_features(struct sk_buff *skb, struct net_device *dev)
+static int harmonize_features(struct sk_buff *skb, __be16 protocol, int features)
+{
+	if (!can_checksum_protocol(protocol, features)) {
+		features &= ~NETIF_F_ALL_CSUM;
+		features &= ~NETIF_F_SG;
+	} else if (illegal_highdma(skb->dev, skb)) {
+		features &= ~NETIF_F_SG;
+	}
+
+	return features;
+}
+
+int netif_skb_features(struct sk_buff *skb)
 {
 	__be16 protocol = skb->protocol;
+	int features = skb->dev->features;
 
 	if (protocol == htons(ETH_P_8021Q)) {
 		struct vlan_ethhdr *veh = (struct vlan_ethhdr *)skb->data;
 		protocol = veh->h_vlan_encapsulated_proto;
-	} else if (!skb->vlan_tci)
-		return dev->features;
+	} else if (!vlan_tx_tag_present(skb)) {
+		return harmonize_features(skb, protocol, features);
+	}
 
-	if (protocol != htons(ETH_P_8021Q))
-		return dev->features & dev->vlan_features;
-	else
-		return 0;
+	features &= skb->dev->vlan_features;
+
+	if (protocol != htons(ETH_P_8021Q)) {
+		return harmonize_features(skb, protocol, features);
+	} else {
+		features &= NETIF_F_SG | NETIF_F_HIGHDMA | NETIF_F_FRAGLIST |
+				NETIF_F_GEN_CSUM;
+		return harmonize_features(skb, protocol, features);
+	}
 }
-EXPORT_SYMBOL(netif_get_vlan_features);
+EXPORT_SYMBOL(netif_skb_features);
 
 /*
  * Returns true if either: