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, 21 insertions, 18 deletions

diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
index 0a49632..92e71d2 100644
--- a/net/dsa/dsa.c
+++ b/net/dsa/dsa.c
@@ -608,6 +608,24 @@ static void dsa_shutdown(struct platform_device *pdev)
 {
 }
 
+static int dsa_switch_rcv(struct sk_buff *skb, struct net_device *dev,
+			  struct packet_type *pt, struct net_device *orig_dev)
+{
+	struct dsa_switch_tree *dst = dev->dsa_ptr;
+
+	if (unlikely(dst == NULL)) {
+		kfree_skb(skb);
+		return 0;
+	}
+
+	return dst->ops->rcv(skb, dev, pt, orig_dev);
+}
+
+struct packet_type dsa_pack_type __read_mostly = {
+	.type	= cpu_to_be16(ETH_P_XDSA),
+	.func	= dsa_switch_rcv,
+};
+
 static const struct of_device_id dsa_of_match_table[] = {
 	{ .compatible = "marvell,dsa", },
 	{}
@@ -633,30 +651,15 @@ static int __init dsa_init_module(void)
 	if (rc)
 		return rc;
 
-#ifdef CONFIG_NET_DSA_TAG_DSA
-	dev_add_pack(&dsa_packet_type);
-#endif
-#ifdef CONFIG_NET_DSA_TAG_EDSA
-	dev_add_pack(&edsa_packet_type);
-#endif
-#ifdef CONFIG_NET_DSA_TAG_TRAILER
-	dev_add_pack(&trailer_packet_type);
-#endif
+	dev_add_pack(&dsa_pack_type);
+
 	return 0;
 }
 module_init(dsa_init_module);
 
 static void __exit dsa_cleanup_module(void)
 {
-#ifdef CONFIG_NET_DSA_TAG_TRAILER
-	dev_remove_pack(&trailer_packet_type);
-#endif
-#ifdef CONFIG_NET_DSA_TAG_EDSA
-	dev_remove_pack(&edsa_packet_type);
-#endif
-#ifdef CONFIG_NET_DSA_TAG_DSA
-	dev_remove_pack(&dsa_packet_type);
-#endif
+	dev_remove_pack(&dsa_pack_type);
 	platform_driver_unregister(&dsa_driver);
 }
 module_exit(dsa_cleanup_module);