tcp: tcp_mtu_probe() is likely to exit early

Adding a likely() in tcp_mtu_probe() moves its code which used to
be inlined in front of tcp_write_xmit()

We still have a cache line miss to access icsk->icsk_mtup.enabled,
we will probably have to reorganize fields to help data locality.

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

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index d5c46749adabf8bd2aea0a9bfe4a5ef5a046c107..5f04bee4c86ab060d72163243b858864a5a589bb 100644 (file)
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1932,26 +1932,26 @@ static inline void tcp_mtu_check_reprobe(struct sock *sk)
  */
 static int tcp_mtu_probe(struct sock *sk)
 {
-       struct tcp_sock *tp = tcp_sk(sk);
        struct inet_connection_sock *icsk = inet_csk(sk);
+       struct tcp_sock *tp = tcp_sk(sk);
        struct sk_buff *skb, *nskb, *next;
        struct net *net = sock_net(sk);
-       int len;
        int probe_size;
        int size_needed;
-       int copy;
+       int copy, len;
        int mss_now;
        int interval;
 
        /* Not currently probing/verifying,
         * not in recovery,
         * have enough cwnd, and
-        * not SACKing (the variable headers throw things off) */
-       if (!icsk->icsk_mtup.enabled ||
-           icsk->icsk_mtup.probe_size ||
-           inet_csk(sk)->icsk_ca_state != TCP_CA_Open ||
-           tp->snd_cwnd < 11 ||
-           tp->rx_opt.num_sacks || tp->rx_opt.dsack)
+        * not SACKing (the variable headers throw things off)
+        */
+       if (likely(!icsk->icsk_mtup.enabled ||
+                  icsk->icsk_mtup.probe_size ||
+                  inet_csk(sk)->icsk_ca_state != TCP_CA_Open ||
+                  tp->snd_cwnd < 11 ||
+                  tp->rx_opt.num_sacks || tp->rx_opt.dsack))
                return -1;
 
        /* Use binary search for probe_size between tcp_mss_base,