From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Tue, 26 May 2009 18:50:26 +0000 (+0000)
Subject: tcp: Optimise len/mss comparison
X-Git-Tag: v2.6.31-rc1~330^2~254
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=30a3ae30c775e2723f86ef70746ad3cb4404a4c9;p=karo-tx-linux.git

tcp: Optimise len/mss comparison

Instead of checking len > mss || len == 0, we can accomplish
both by checking (len - 1) > mss using the unsigned wraparound.
At nearly a million times a second, this might just help.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 313960e4cfdc..68342d431896 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2566,7 +2566,7 @@ found:
 
 	mss = skb_shinfo(p)->gso_size;
 
-	flush |= (len > mss) | !len;
+	flush |= (len - 1) >= mss;
 	flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);
 
 	if (flush || skb_gro_receive(head, skb)) {