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ethernet: use likely() for common Ethernet encap 

Mark code path's likely/unlikely based on most common usage.
  * Very few devices use dsa tags.
  * Most traffic is Ethernet (not 802.2)
  * No sane person uses trailer type or Novell encapsulation

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
stephen hemminger 2013-09-27 17:21:27 -07:00 committed by David S. Miller
parent 12861b7bc2
commit 56d7b53f47
1 changed files with 5 additions and 4 deletions
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9
net/ethernet/eth.c
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@ -179,12 +179,13 @@ __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev)
* variants has been configured on the receiving interface,
* and if so, set skb->protocol without looking at the packet.
*/
if (netdev_uses_dsa_tags(dev))
if (unlikely(netdev_uses_dsa_tags(dev)))
return htons(ETH_P_DSA);
if (netdev_uses_trailer_tags(dev))
if (unlikely(netdev_uses_trailer_tags(dev)))
return htons(ETH_P_TRAILER);
if (ntohs(eth->h_proto) >= ETH_P_802_3_MIN)
if (likely(ntohs(eth->h_proto) >= ETH_P_802_3_MIN))
return eth->h_proto;
/*
@ -193,7 +194,7 @@ __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev)
* layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
* won't work for fault tolerant netware but does for the rest.
*/
if (skb->len >= 2 && *(unsigned short *)(skb->data) == 0xFFFF)
if (unlikely(skb->len >= 2 && *(unsigned short *)(skb->data) == 0xFFFF))
return htons(ETH_P_802_3);
/*