[NET]: Share correct feature code between bridging and bonding

http://bugzilla.kernel.org/show_bug.cgi?id=8797 shows that the
bonding driver may produce bogus combinations of the checksum
flags and SG/TSO.

For example, if you bond devices with NETIF_F_HW_CSUM and
NETIF_F_IP_CSUM you'll end up with a bonding device that
has neither flag set.  If both have TSO then this produces
an illegal combination.

The bridge device on the other hand has the correct code to
deal with this.

In fact, the same code can be used for both.  So this patch
moves that logic into net/core/dev.c and uses it for both
bonding and bridging.

In the process I've made small adjustments such as only
setting GSO_ROBUST if at least one constituent device
supports it.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 13 insertions, 21 deletions

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 070b78d..1afda32 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1202,43 +1202,35 @@ static int bond_sethwaddr(struct net_device *bond_dev,
 	return 0;
 }
 
-#define BOND_INTERSECT_FEATURES \
-	(NETIF_F_SG | NETIF_F_ALL_CSUM | NETIF_F_TSO | NETIF_F_UFO)
+#define BOND_VLAN_FEATURES \
+	(NETIF_F_VLAN_CHALLENGED | NETIF_F_HW_VLAN_RX | NETIF_F_HW_VLAN_TX | \
+	 NETIF_F_HW_VLAN_FILTER)
 
 /* 
  * Compute the common dev->feature set available to all slaves.  Some
- * feature bits are managed elsewhere, so preserve feature bits set on
- * master device that are not part of the examined set.
+ * feature bits are managed elsewhere, so preserve those feature bits
+ * on the master device.
  */
 static int bond_compute_features(struct bonding *bond)
 {
-	unsigned long features = BOND_INTERSECT_FEATURES;
 	struct slave *slave;
 	struct net_device *bond_dev = bond->dev;
+	unsigned long features = bond_dev->features;
 	unsigned short max_hard_header_len = ETH_HLEN;
 	int i;
 
+	features &= ~(NETIF_F_ALL_CSUM | BOND_VLAN_FEATURES);
+	features |= NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_HIGHDMA |
+		    NETIF_F_GSO_MASK | NETIF_F_NO_CSUM;
+
 	bond_for_each_slave(bond, slave, i) {
-		features &= (slave->dev->features & BOND_INTERSECT_FEATURES);
+		features = netdev_compute_features(features,
+						   slave->dev->features);
 		if (slave->dev->hard_header_len > max_hard_header_len)
 			max_hard_header_len = slave->dev->hard_header_len;
 	}
 
-	if ((features & NETIF_F_SG) && 
-	    !(features & NETIF_F_ALL_CSUM))
-		features &= ~NETIF_F_SG;
-
-	/* 
-	 * features will include NETIF_F_TSO (NETIF_F_UFO) iff all 
-	 * slave devices support NETIF_F_TSO (NETIF_F_UFO), which 
-	 * implies that all slaves also support scatter-gather 
-	 * (NETIF_F_SG), which implies that features also includes 
-	 * NETIF_F_SG. So no need to check whether we have an  
-	 * illegal combination of NETIF_F_{TSO,UFO} and 
-	 * !NETIF_F_SG 
-	 */
-
-	features |= (bond_dev->features & ~BOND_INTERSECT_FEATURES);
+	features |= (bond_dev->features & BOND_VLAN_FEATURES);
 	bond_dev->features = features;
 	bond_dev->hard_header_len = max_hard_header_len;