From d65746088d2de3a7c1d569e73a5ef3a764d071a4 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Mon, 22 Jul 2019 06:47:33 +0000
Subject: [PATCH] tcp: hint compiler about sack flows

mainline inclusion
from mainline-v5.0-rc1
commit ebeef4bcccf4681ba3de04fbf3a005f6054f7999
category: perf
bugzilla: NA
CVE: NA

-------------------------------------------------
Tell the compiler that most TCP flows are using SACK these days.

There is no need to add the unlikely() clause in tcp_is_reno(),
the compiler is able to infer it.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Biaoxiang <yebiaoxiang@huawei.com>
Reviewed-by: Mao Wenan <maowenan@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
---
 include/net/tcp.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index e75661f92daa..741154d70a9a 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1115,7 +1115,7 @@ void tcp_rate_check_app_limited(struct sock *sk);
  */
 static inline int tcp_is_sack(const struct tcp_sock *tp)
 {
-	return tp->rx_opt.sack_ok;
+	return likely(tp->rx_opt.sack_ok);
 }
 
 static inline bool tcp_is_reno(const struct tcp_sock *tp)
-- 
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