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>

1 files changed, 9 insertions, 9 deletions

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index d5c46749adab..5f04bee4c86a 100644
--- 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,