tcp: tcp_tso_segment() small optimization

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>

1 files changed, 5 insertions, 2 deletions

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 963bda18486f..dcb116dde216 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2886,6 +2886,7 @@ struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
         unsigned int oldlen;
         unsigned int mss;
         struct sk_buff *gso_skb = skb;
+        __sum16 newcheck;
 
         if (!pskb_may_pull(skb, sizeof(*th)))
                 goto out;
@@ -2936,11 +2937,13 @@ struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
         th = tcp_hdr(skb);
         seq = ntohl(th->seq);
 
+        newcheck = ~csum_fold((__force __wsum)((__force u32)th->check +
+                                               (__force u32)delta));
+
         do {
                 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)
                         th->check =
                              csum_fold(csum_partial(skb_transport_header(skb),