From mboxrd@z Thu Jan  1 00:00:00 1970
From: Octavian Purdila <opurdila@ixiacom.com>
Subject: [RFC] [PATCH] ip: skip IP checksum for skbs with CHECKSUM_UNNECESSARY set
Date: Fri, 22 Aug 2008 22:24:31 +0300
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We are working on a completely in hardware LRO implementation and this patch 
would simplify the hardware implementation. Is this acceptable?

--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -415,7 +415,8 @@ int ip_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt,
 
        iph = ip_hdr(skb);
 
-       if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
+       if (!skb_csum_unnecessary(skb) &&
+           unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
                goto inhdr_error;
 
        len = ntohs(iph->tot_len);