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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

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))

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html