tcp: gro: micro optimizations in tcp[4]_gro_complete()

In tcp_gro_complete() :

Moving the skb->inner_transport_header setting
allows the compiler to reuse the previously loaded value
of skb->transport_header.

Caching skb_shinfo() avoids duplications as well.

In tcp4_gro_complete(), doing a single change on
skb_shinfo(skb)->gso_type also generates better code.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c
index 875456efc92ddd546e13232dd775aaaf1093ce4f..b955ab3b236d965a38054efa004fe12f03074c70 100644 (file)
--- a/net/ipv4/tcp_offload.c
+++ b/net/ipv4/tcp_offload.c
@@ -299,18 +299,20 @@ out:
 void tcp_gro_complete(struct sk_buff *skb)
 {
        struct tcphdr *th = tcp_hdr(skb);
+       struct skb_shared_info *shinfo;
+
+       if (skb->encapsulation)
+               skb->inner_transport_header = skb->transport_header;
 
        skb->csum_start = (unsigned char *)th - skb->head;
        skb->csum_offset = offsetof(struct tcphdr, check);
        skb->ip_summed = CHECKSUM_PARTIAL;
 
-       skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
+       shinfo = skb_shinfo(skb);
+       shinfo->gso_segs = NAPI_GRO_CB(skb)->count;
 
        if (th->cwr)
-               skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
-
-       if (skb->encapsulation)
-               skb->inner_transport_header = skb->transport_header;
+               shinfo->gso_type |= SKB_GSO_TCP_ECN;
 }
 EXPORT_SYMBOL(tcp_gro_complete);
 
@@ -335,10 +337,9 @@ INDIRECT_CALLABLE_SCOPE int tcp4_gro_complete(struct sk_buff *skb, int thoff)
 
        th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr,
                                  iph->daddr, 0);
-       skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4;
 
-       if (NAPI_GRO_CB(skb)->is_atomic)
-               skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_FIXEDID;
+       skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4 |
+                       (NAPI_GRO_CB(skb)->is_atomic * SKB_GSO_TCP_FIXEDID);
 
        tcp_gro_complete(skb);
        return 0;