[PATCH RFC] net: unify features for drivers which use skb_copy_and_csum_dev

[Cesar Eduardo Barros <cesarb@cesarb.net>]

A few network drivers use skb_copy_and_csum_dev as the core of their
.ndo_start_xmit function. Which NETIF_F_* features these drivers can use
should depend only on the implementation of skb_copy_and_csum_dev, and
so should be the same for all of them.  However, I could find three
different sets of feature flags on these drivers.

To prevent these drivers from getting out of sync again, move this set
of feature flags to a central location. With the advantage that if the
set of flags is later found to be wrong or skb_copy_and_csum_dev is
modified, it can be changed in a single place.

This also enables NETIF_F_FRAGLIST for these drivers. Unless I misread
the code behind skb_copy_and_csum_dev, it can also deal with frag lists.

There were other drivers using skb_copy_and_csum_dev (ksz884x and
via-rhine), but I did not touch them, since they are doing things on
their .ndo_start_xmit which are more complex than a simple call of
skb_copy_and_csum_dev.

Cc: Jeff Garzik <jgarzik@pobox.com> (8139too)
Cc: Lennert Buytenhek <kernel@wantstofly.org> (ep93xx_eth, ixp2000)
Cc: Tristram Ha <Tristram.Ha@micrel.com> (ksz884x)
Cc: Roger Luethi <rl@hellgate.ch> (via-rhine)
Cc: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
---
 drivers/net/8139too.c        |    2 +-
 drivers/net/arm/ep93xx_eth.c |    2 +-
 drivers/net/ixp2000/ixpdev.c |    2 +-
 drivers/net/sc92031.c        |    3 +--
 include/linux/netdevice.h    |    4 ++++
 5 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/net/8139too.c b/drivers/net/8139too.c
index 98517a3..0fc2127 100644
--- a/drivers/net/8139too.c
+++ b/drivers/net/8139too.c
@@ -991,7 +991,7 @@ static int __devinit rtl8139_init_one (struct pci_dev *pdev,
 	 * through the use of skb_copy_and_csum_dev we enable these
 	 * features
 	 */
-	dev->features |= NETIF_F_SG | NETIF_F_HW_CSUM | NETIF_F_HIGHDMA;
+	dev->features |= NETIF_F_XMIT_COPY_AND_CSUM;
 
 	dev->irq = pdev->irq;
 
diff --git a/drivers/net/arm/ep93xx_eth.c b/drivers/net/arm/ep93xx_eth.c
index 5a77001..50ebd33 100644
--- a/drivers/net/arm/ep93xx_eth.c
+++ b/drivers/net/arm/ep93xx_eth.c
@@ -769,7 +769,7 @@ static struct net_device *ep93xx_dev_alloc(struct ep93xx_eth_data *data)
 	dev->ethtool_ops = &ep93xx_ethtool_ops;
 	dev->netdev_ops = &ep93xx_netdev_ops;
 
-	dev->features |= NETIF_F_SG | NETIF_F_HW_CSUM;
+	dev->features |= NETIF_F_XMIT_COPY_AND_CSUM;
 
 	return dev;
 }
diff --git a/drivers/net/ixp2000/ixpdev.c b/drivers/net/ixp2000/ixpdev.c
index 78ddd8b..0df0734 100644
--- a/drivers/net/ixp2000/ixpdev.c
+++ b/drivers/net/ixp2000/ixpdev.c
@@ -303,7 +303,7 @@ struct net_device *ixpdev_alloc(int channel, int sizeof_priv)
 
 	dev->netdev_ops = &ixpdev_netdev_ops;
 
-	dev->features |= NETIF_F_SG | NETIF_F_HW_CSUM;
+	dev->features |= NETIF_F_XMIT_COPY_AND_CSUM;
 
 	ip = netdev_priv(dev);
 	ip->dev = dev;
diff --git a/drivers/net/sc92031.c b/drivers/net/sc92031.c
index 76290a8..63db429 100644
--- a/drivers/net/sc92031.c
+++ b/drivers/net/sc92031.c
@@ -1449,8 +1449,7 @@ static int __devinit sc92031_probe(struct pci_dev *pdev,
 	dev->irq = pdev->irq;
 
 	/* faked with skb_copy_and_csum_dev */
-	dev->features = NETIF_F_SG | NETIF_F_HIGHDMA |
-		NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM;
+	dev->features = NETIF_F_XMIT_COPY_AND_CSUM;
 
 	dev->netdev_ops		= &sc92031_netdev_ops;
 	dev->watchdog_timeo	= TX_TIMEOUT;
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 5eeb2cd..680ed33 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1110,6 +1110,10 @@ struct net_device {
 	/* changeable features with no special hardware requirements */
 #define NETIF_F_SOFT_FEATURES	(NETIF_F_GSO | NETIF_F_GRO)
 
+	/* skb_copy_and_csum_dev is able to fake a few features */
+#define NETIF_F_XMIT_COPY_AND_CSUM	(NETIF_F_SG | NETIF_F_HW_CSUM | \
+					 NETIF_F_HIGHDMA | NETIF_F_FRAGLIST)
+
 	/* Interface index. Unique device identifier	*/
 	int			ifindex;
 	int			iflink;
-- 
1.7.4