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, 3 insertions, 17 deletions

diff --git a/include/net/dsa.h b/include/net/dsa.h
index 6efce384451e..6e26f1e4d8ce 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -59,6 +59,8 @@ struct dsa_platform_data {
         struct dsa_chip_data    *chip;
 };
 
+struct dsa_device_ops;
+
 struct dsa_switch_tree {
         /*
          * Configuration data for the platform device that owns
@@ -71,6 +73,7 @@ struct dsa_switch_tree {
          * protocol to use.
          */
         struct net_device       *master_netdev;
+        const struct dsa_device_ops     *ops;
         __be16                  tag_protocol;
 
         /*
@@ -186,21 +189,4 @@ static inline void *ds_to_priv(struct dsa_switch *ds)
         return (void *)(ds + 1);
 }
 
-/*
- * The original DSA tag format and some other tag formats have no
- * ethertype, which means that we need to add a little hack to the
- * networking receive path to make sure that received frames get
- * the right ->protocol assigned to them when one of those tag
- * formats is in use.
- */
-static inline bool dsa_uses_dsa_tags(struct dsa_switch_tree *dst)
-{
-        return !!(dst->tag_protocol == htons(ETH_P_DSA));
-}
-
-static inline bool dsa_uses_trailer_tags(struct dsa_switch_tree *dst)
-{
-        return !!(dst->tag_protocol == htons(ETH_P_TRAILER));
-}
-
 #endif