netdev - [PATCH 3/3] etherdev: Use skb->data to retrieve Ethernet header instead of eth

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Message-ID: <20150430215359.1798.79917.stgit@ahduyck-vm-fedora22>
Date:	Thu, 30 Apr 2015 14:53:59 -0700
From:	Alexander Duyck <alexander.h.duyck@...hat.com>
To:	netdev@...r.kernel.org
Cc:	davem@...emloft.net
Subject: [PATCH 3/3] etherdev: Use skb->data to retrieve Ethernet header
 instead of eth_hdr

Avoid recomputing the Ethernet header location and instead just use the
pointer provided by skb->data.  The problem with using eth_hdr is that the
compiler wasn't smart enough to realize that skb->head + skb->mac_header
was the same thing as skb->data before it added ETH_HLEN.  By just caching
it off before calling skb_pull_inline we can avoid a few unnecessary
instructions.

Signed-off-by: Alexander Duyck <alexander.h.duyck@...hat.com>
---
 net/ethernet/eth.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c
index 21c211e9fd5a..314e4c5a5a5e 100644
--- a/net/ethernet/eth.c
+++ b/net/ethernet/eth.c
@@ -156,8 +156,9 @@ __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev)
 
 	skb->dev = dev;
 	skb_reset_mac_header(skb);
+
+	eth = (struct ethhdr *)skb->data;
 	skb_pull_inline(skb, ETH_HLEN);
-	eth = eth_hdr(skb);
 
 	if (unlikely(is_multicast_ether_addr_64bits(eth->h_dest))) {
 		if (ether_addr_equal_64bits(eth->h_dest, dev->broadcast))

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