net: Eliminate NETIF_F_GEN_CSUM and NETIF_F_V[46]_CSUM

These netif flags are unnecessary convolutions. It is more
straightforward to just use NETIF_F_HW_CSUM, NETIF_F_IP_CSUM,
and NETIF_F_IPV6_CSUM directly.

This patch also:
    - Cleans up can_checksum_protocol
    - Simplifies netdev_intersect_features

Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 29 insertions, 22 deletions

diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h
index 05f5879821b8..a5f6ce6b578c 100644
--- a/include/linux/if_vlan.h
+++ b/include/linux/if_vlan.h
@@ -621,7 +621,7 @@ static inline netdev_features_t vlan_features_check(const struct sk_buff *skb,
 						     NETIF_F_SG |
 						     NETIF_F_HIGHDMA |
 						     NETIF_F_FRAGLIST |
-						     NETIF_F_GEN_CSUM |
+						     NETIF_F_HW_CSUM |
 						     NETIF_F_HW_VLAN_CTAG_TX |
 						     NETIF_F_HW_VLAN_STAG_TX);
 
diff --git a/include/linux/netdev_features.h b/include/linux/netdev_features.h
index 2c4e94ab88da..d9654f0eecb3 100644
--- a/include/linux/netdev_features.h
+++ b/include/linux/netdev_features.h
@@ -146,15 +146,12 @@ enum {
 #define NETIF_F_GSO_SOFTWARE	(NETIF_F_TSO | NETIF_F_TSO_ECN | \
 				 NETIF_F_TSO6 | NETIF_F_UFO)
 
-#define NETIF_F_GEN_CSUM	NETIF_F_HW_CSUM
-#define NETIF_F_V4_CSUM		(NETIF_F_GEN_CSUM | NETIF_F_IP_CSUM)
-#define NETIF_F_V6_CSUM		(NETIF_F_GEN_CSUM | NETIF_F_IPV6_CSUM)
-
-/* List of IP checksum features. Note that NETIF_HW_CSUM should not be
+/* List of IP checksum features. Note that NETIF_F_ HW_CSUM should not be
  * set in features when NETIF_F_IP_CSUM or NETIF_F_IPV6_CSUM are set--
  * this would be contradictory
  */
-#define NETIF_F_CSUM_MASK	(NETIF_F_V4_CSUM | NETIF_F_V6_CSUM)
+#define NETIF_F_CSUM_MASK	(NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM | \
+				 NETIF_F_HW_CSUM)
 
 #define NETIF_F_ALL_TSO 	(NETIF_F_TSO | NETIF_F_TSO6 | NETIF_F_TSO_ECN)
 
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index a54223a113b1..283984b67cd9 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3691,13 +3691,24 @@ __be16 skb_network_protocol(struct sk_buff *skb, int *depth);
 static inline bool can_checksum_protocol(netdev_features_t features,
 					 __be16 protocol)
 {
-	return ((features & NETIF_F_GEN_CSUM) ||
-		((features & NETIF_F_V4_CSUM) &&
-		 protocol == htons(ETH_P_IP)) ||
-		((features & NETIF_F_V6_CSUM) &&
-		 protocol == htons(ETH_P_IPV6)) ||
-		((features & NETIF_F_FCOE_CRC) &&
-		 protocol == htons(ETH_P_FCOE)));
+	if (protocol == htons(ETH_P_FCOE))
+		return !!(features & NETIF_F_FCOE_CRC);
+
+	/* Assume this is an IP checksum (not SCTP CRC) */
+
+	if (features & NETIF_F_HW_CSUM) {
+		/* Can checksum everything */
+		return true;
+	}
+
+	switch (protocol) {
+	case htons(ETH_P_IP):
+		return !!(features & NETIF_F_IP_CSUM);
+	case htons(ETH_P_IPV6):
+		return !!(features & NETIF_F_IPV6_CSUM);
+	default:
+		return false;
+	}
 }
 
 #ifdef CONFIG_BUG
@@ -3762,15 +3773,14 @@ 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_CSUM_MASK & ~NETIF_F_GEN_CSUM);
-	if (f2 & NETIF_F_GEN_CSUM)
-		f2 |= (NETIF_F_CSUM_MASK & ~NETIF_F_GEN_CSUM);
-	f1 &= f2;
-	if (f1 & NETIF_F_GEN_CSUM)
-		f1 &= ~(NETIF_F_CSUM_MASK & ~NETIF_F_GEN_CSUM);
+	if ((f1 ^ f2) & NETIF_F_HW_CSUM) {
+		if (f1 & NETIF_F_HW_CSUM)
+			f1 |= (NETIF_F_IP_CSUM|NETIF_F_IP_CSUM);
+		else
+			f2 |= (NETIF_F_IP_CSUM|NETIF_F_IP_CSUM);
+	}
 
-	return f1;
+	return f1 & f2;
 }
 
 static inline netdev_features_t netdev_get_wanted_features(