tcp: use tcp_flags in tcp_data_queue()

This patch is a cleanup which follows the idea in commit e11ecddf5128 (tcp: use
TCP_SKB_CB(skb)->tcp_flags in input path),
and it may reduce register pressure since skb->cb[] access is fast,
bacause skb is probably in a register.

v2: remove variable th
v3: reword the changelog

Signed-off-by: Weiping Pan <panweiping3@gmail.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 2c0af90..5073eef 100644 (file)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4344,7 +4344,6 @@ err:
 
 static void tcp_data_queue(struct sock *sk, struct sk_buff *skb)
 {
-       const struct tcphdr *th = tcp_hdr(skb);
        struct tcp_sock *tp = tcp_sk(sk);
        int eaten = -1;
        bool fragstolen = false;
@@ -4353,7 +4352,7 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb)
                goto drop;
 
        skb_dst_drop(skb);
-       __skb_pull(skb, th->doff * 4);
+       __skb_pull(skb, tcp_hdr(skb)->doff * 4);
 
        TCP_ECN_accept_cwr(tp, skb);
 
@@ -4397,7 +4396,7 @@ queue_and_out:
                tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
                if (skb->len)
                        tcp_event_data_recv(sk, skb);
-               if (th->fin)
+               if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
                        tcp_fin(sk);
 
                if (!skb_queue_empty(&tp->out_of_order_queue)) {