gro: Avoid unnecessary comparison after skb_gro_header
For the overwhelming majority of cases, skb_gro_header's return
value cannot be NULL. Yet we must check it because of its current
form. This patch splits it up into multiple functions in order
to avoid this.
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 68342d4..c3dcec5 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2518,20 +2518,30 @@
unsigned int thlen;
unsigned int flags;
unsigned int mss = 1;
+ unsigned int hlen;
+ unsigned int off;
int flush = 1;
int i;
- th = skb_gro_header(skb, sizeof(*th));
- if (unlikely(!th))
- goto out;
+ off = skb_gro_offset(skb);
+ hlen = off + sizeof(*th);
+ th = skb_gro_header_fast(skb, off);
+ if (skb_gro_header_hard(skb, hlen)) {
+ th = skb_gro_header_slow(skb, hlen, off);
+ if (unlikely(!th))
+ goto out;
+ }
thlen = th->doff * 4;
if (thlen < sizeof(*th))
goto out;
- th = skb_gro_header(skb, thlen);
- if (unlikely(!th))
- goto out;
+ hlen = off + thlen;
+ if (skb_gro_header_hard(skb, hlen)) {
+ th = skb_gro_header_slow(skb, hlen, off);
+ if (unlikely(!th))
+ goto out;
+ }
skb_gro_pull(skb, thlen);
