net/ethernet: Add parse_protocol header_ops support

The previous commit introduced parse_protocol callback which should
extract the protocol number from the L2 header. Make all Ethernet
devices support it.

Signed-off-by: Maxim Mikityanskiy <maximmi@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/etherdevice.h

@@ -44,6 +44,7 @@ int eth_header_cache(const struct neighbour *neigh, struct hh_cache *hh,
 		     __be16 type);
 void eth_header_cache_update(struct hh_cache *hh, const struct net_device *dev,
 			     const unsigned char *haddr);
+__be16 eth_header_parse_protocol(const struct sk_buff *skb);
 int eth_prepare_mac_addr_change(struct net_device *dev, void *p);
 void eth_commit_mac_addr_change(struct net_device *dev, void *p);
 int eth_mac_addr(struct net_device *dev, void *p);

net/ethernet/eth.c

@@ -264,6 +264,18 @@ void eth_header_cache_update(struct hh_cache *hh,
 }
 EXPORT_SYMBOL(eth_header_cache_update);
 
+/**
+ * eth_header_parser_protocol - extract protocol from L2 header
+ * @skb: packet to extract protocol from
+ */
+__be16 eth_header_parse_protocol(const struct sk_buff *skb)
+{
+	const struct ethhdr *eth = eth_hdr(skb);
+
+	return eth->h_proto;
+}
+EXPORT_SYMBOL(eth_header_parse_protocol);
+
 /**
  * eth_prepare_mac_addr_change - prepare for mac change
  * @dev: network device
@@ -346,6 +358,7 @@ const struct header_ops eth_header_ops ____cacheline_aligned = {
 	.parse		= eth_header_parse,
 	.cache		= eth_header_cache,
 	.cache_update	= eth_header_cache_update,
+	.parse_protocol	= eth_header_parse_protocol,
 };
 
 /**