linux-kernel - [PATCH AUTOSEL for 4.9 098/100] tcp: fix under-evaluated ssthresh in TCP Vegas

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Message-ID: <20171213015722.6722-73-alexander.levin@verizon.com>
Date:   Wed, 13 Dec 2017 01:57:47 +0000
From:   alexander.levin@...izon.com
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Cc:     Hoang Tran <tranviethoang.vn@...il.com>,
        Hoang Tran <hoang.tran@...ouvain.be>,
        "David S . Miller" <davem@...emloft.net>,
        alexander.levin@...izon.com
Subject: [PATCH AUTOSEL for 4.9 098/100] tcp: fix under-evaluated ssthresh in
 TCP Vegas

From: Hoang Tran <tranviethoang.vn@...il.com>

[ Upstream commit cf5d74b85ef40c202c76d90959db4d850f301b95 ]

With the commit 76174004a0f19785 (tcp: do not slow start when cwnd equals
ssthresh), the comparison to the reduced cwnd in tcp_vegas_ssthresh() would
under-evaluate the ssthresh.

Signed-off-by: Hoang Tran <hoang.tran@...ouvain.be>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
---
 net/ipv4/tcp_vegas.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/tcp_vegas.c b/net/ipv4/tcp_vegas.c
index 4c4bac1b5eab..3ecb61ee42fb 100644
--- a/net/ipv4/tcp_vegas.c
+++ b/net/ipv4/tcp_vegas.c
@@ -158,7 +158,7 @@ EXPORT_SYMBOL_GPL(tcp_vegas_cwnd_event);
 
 static inline u32 tcp_vegas_ssthresh(struct tcp_sock *tp)
 {
-	return  min(tp->snd_ssthresh, tp->snd_cwnd-1);
+	return  min(tp->snd_ssthresh, tp->snd_cwnd);
 }
 
 static void tcp_vegas_cong_avoid(struct sock *sk, u32 ack, u32 acked)
-- 
2.11.0