netdev - [PATCH net-next 1/5] tcp: fix stretch ACK bugs in BIC

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Message-Id: <1584118044-9798-1-git-send-email-yangpc@wangsu.com>
Date:   Sat, 14 Mar 2020 00:47:20 +0800
From:   Pengcheng Yang <yangpc@...gsu.com>
To:     edumazet@...gle.com, davem@...emloft.net, ncardwell@...gle.com
Cc:     netdev@...r.kernel.org, Pengcheng Yang <yangpc@...gsu.com>
Subject: [PATCH net-next 1/5] tcp: fix stretch ACK bugs in BIC

Neal Cardwell submits a series of patches to handle stretched ACKs,
which start with commit e73ebb0881ea ("tcp: stretch ACK fixes prep").

This patch changes BIC to properly handle stretch ACKs in additive
increase mode by passing in the count of ACKed packets to
tcp_cong_avoid_ai().

Signed-off-by: Pengcheng Yang <yangpc@...gsu.com>
---
 net/ipv4/tcp_bic.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/net/ipv4/tcp_bic.c b/net/ipv4/tcp_bic.c
index 645cc30..f5f588b 100644
--- a/net/ipv4/tcp_bic.c
+++ b/net/ipv4/tcp_bic.c
@@ -145,12 +145,13 @@ static void bictcp_cong_avoid(struct sock *sk, u32 ack, u32 acked)
 	if (!tcp_is_cwnd_limited(sk))
 		return;
 
-	if (tcp_in_slow_start(tp))
-		tcp_slow_start(tp, acked);
-	else {
-		bictcp_update(ca, tp->snd_cwnd);
-		tcp_cong_avoid_ai(tp, ca->cnt, 1);
+	if (tcp_in_slow_start(tp)) {
+		acked = tcp_slow_start(tp, acked);
+		if (!acked)
+			return;
 	}
+	bictcp_update(ca, tp->snd_cwnd);
+	tcp_cong_avoid_ai(tp, ca->cnt, acked);
 }
 
 /*
-- 
1.8.3.1