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tcp: tcp_tso_segment() small optimization

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We can move th->check computation out of the loop, as compiler
doesn't know each skb initially share same tcp headers after
skb_segment()

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2013-04-13 03:22:08 +00:00
committed by David S. Miller
parent eb1d064058
commit bece1b9708
1 changed files with 5 additions and 2 deletions
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7
net/ipv4/tcp.c
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@@ -2886,6 +2886,7 @@ struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
unsigned int oldlen; unsigned int oldlen;
unsigned int mss; unsigned int mss;
struct sk_buff *gso_skb = skb; struct sk_buff *gso_skb = skb;
__sum16 newcheck;
if (!pskb_may_pull(skb, sizeof(*th))) if (!pskb_may_pull(skb, sizeof(*th)))
goto out; goto out;
@@ -2936,11 +2937,13 @@ struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
th = tcp_hdr(skb); th = tcp_hdr(skb);
seq = ntohl(th->seq); seq = ntohl(th->seq);
newcheck = ~csum_fold((__force __wsum)((__force u32)th->check +
(__force u32)delta));
do { do {
th->fin = th->psh = 0; th->fin = th->psh = 0;
th->check = newcheck;
th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
(__force u32)delta));
if (skb->ip_summed != CHECKSUM_PARTIAL) if (skb->ip_summed != CHECKSUM_PARTIAL)
th->check = th->check =
csum_fold(csum_partial(skb_transport_header(skb), csum_fold(csum_partial(skb_transport_header(skb),