net: dsa: reduce number of protocol hooks

DSA is currently registering one packet_type function per EtherType it
needs to intercept in the receive path of a DSA-enabled Ethernet device.
Right now we have three of them: trailer, DSA and eDSA, and there might
be more in the future, this will not scale to the addition of new
protocols.

This patch proceeds with adding a new layer of abstraction and two new
functions:

dsa_switch_rcv() which will dispatch into the tag-protocol specific
receive function implemented by net/dsa/tag_*.c

dsa_slave_xmit() which will dispatch into the tag-protocol specific
transmit function implemented by net/dsa/tag_*.c

When we do create the per-port slave network devices, we iterate over
the switch protocol to assign the DSA-specific receive and transmit
operations.

A new fake ethertype value is used: ETH_P_XDSA to illustrate the fact
that this is no longer going to look like ETH_P_DSA or ETH_P_TRAILER
like it used to be.

This allows us to greatly simplify the check in eth_type_trans() and
always override the skb->protocol with ETH_P_XDSA for Ethernet switches
tagged protocol, while also reducing the number repetitive slave
netdevice_ops assignments.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 31 deletions

diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index 45a1e34c89e..ad1a913533a 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -171,6 +171,14 @@ static int dsa_slave_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 	return -EOPNOTSUPP;
 }
 
+static netdev_tx_t dsa_slave_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	struct dsa_slave_priv *p = netdev_priv(dev);
+	struct dsa_switch_tree *dst = p->parent->dst;
+
+	return dst->ops->xmit(skb, dev);
+}
+
 
 /* ethtool operations *******************************************************/
 static int
@@ -293,42 +301,16 @@ static const struct ethtool_ops dsa_slave_ethtool_ops = {
 	.get_sset_count		= dsa_slave_get_sset_count,
 };
 
-#ifdef CONFIG_NET_DSA_TAG_DSA
-static const struct net_device_ops dsa_netdev_ops = {
+static const struct net_device_ops dsa_slave_netdev_ops = {
 	.ndo_init		= dsa_slave_init,
 	.ndo_open	 	= dsa_slave_open,
 	.ndo_stop		= dsa_slave_close,
-	.ndo_start_xmit		= dsa_xmit,
+	.ndo_start_xmit		= dsa_slave_xmit,
 	.ndo_change_rx_flags	= dsa_slave_change_rx_flags,
 	.ndo_set_rx_mode	= dsa_slave_set_rx_mode,
 	.ndo_set_mac_address	= dsa_slave_set_mac_address,
 	.ndo_do_ioctl		= dsa_slave_ioctl,
 };
-#endif
-#ifdef CONFIG_NET_DSA_TAG_EDSA
-static const struct net_device_ops edsa_netdev_ops = {
-	.ndo_init		= dsa_slave_init,
-	.ndo_open	 	= dsa_slave_open,
-	.ndo_stop		= dsa_slave_close,
-	.ndo_start_xmit		= edsa_xmit,
-	.ndo_change_rx_flags	= dsa_slave_change_rx_flags,
-	.ndo_set_rx_mode	= dsa_slave_set_rx_mode,
-	.ndo_set_mac_address	= dsa_slave_set_mac_address,
-	.ndo_do_ioctl		= dsa_slave_ioctl,
-};
-#endif
-#ifdef CONFIG_NET_DSA_TAG_TRAILER
-static const struct net_device_ops trailer_netdev_ops = {
-	.ndo_init		= dsa_slave_init,
-	.ndo_open	 	= dsa_slave_open,
-	.ndo_stop		= dsa_slave_close,
-	.ndo_start_xmit		= trailer_xmit,
-	.ndo_change_rx_flags	= dsa_slave_change_rx_flags,
-	.ndo_set_rx_mode	= dsa_slave_set_rx_mode,
-	.ndo_set_mac_address	= dsa_slave_set_mac_address,
-	.ndo_do_ioctl		= dsa_slave_ioctl,
-};
-#endif
 
 /* slave device setup *******************************************************/
 struct net_device *
@@ -349,21 +331,22 @@ dsa_slave_create(struct dsa_switch *ds, struct device *parent,
 	slave_dev->ethtool_ops = &dsa_slave_ethtool_ops;
 	eth_hw_addr_inherit(slave_dev, master);
 	slave_dev->tx_queue_len = 0;
+	slave_dev->netdev_ops = &dsa_slave_netdev_ops;
 
 	switch (ds->dst->tag_protocol) {
 #ifdef CONFIG_NET_DSA_TAG_DSA
 	case htons(ETH_P_DSA):
-		slave_dev->netdev_ops = &dsa_netdev_ops;
+		ds->dst->ops = &dsa_netdev_ops;
 		break;
 #endif
 #ifdef CONFIG_NET_DSA_TAG_EDSA
 	case htons(ETH_P_EDSA):
-		slave_dev->netdev_ops = &edsa_netdev_ops;
+		ds->dst->ops = &edsa_netdev_ops;
 		break;
 #endif
 #ifdef CONFIG_NET_DSA_TAG_TRAILER
 	case htons(ETH_P_TRAILER):
-		slave_dev->netdev_ops = &trailer_netdev_ops;
+		ds->dst->ops = &trailer_netdev_ops;
 		break;
 #endif
 	default: