netdev - [PATH net 3/4] tcp: fix off-by-one bug in RACK

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Message-Id: <20171207193333.59039-4-ycheng@google.com>
Date:   Thu,  7 Dec 2017 11:33:32 -0800
From:   Yuchung Cheng <ycheng@...gle.com>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, edumazet@...gle.com, ncardwell@...gle.com,
        priyarjha@...gle.com, Yuchung Cheng <ycheng@...gle.com>
Subject: [PATH net 3/4] tcp: fix off-by-one bug in RACK

RACK should mark a packet lost when remaining wait time is zero.

Signed-off-by: Yuchung Cheng <ycheng@...gle.com>
Reviewed-by: Neal Cardwell <ncardwell@...gle.com>
Reviewed-by: Priyaranjan Jha <priyarjha@...gle.com>
Reviewed-by: Eric Dumazet <edumazet@...gle.com>
---
 net/ipv4/tcp_recovery.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/tcp_recovery.c b/net/ipv4/tcp_recovery.c
index 3143664902e9..0c182303e62e 100644
--- a/net/ipv4/tcp_recovery.c
+++ b/net/ipv4/tcp_recovery.c
@@ -80,12 +80,12 @@ static void tcp_rack_detect_loss(struct sock *sk, u32 *reo_timeout)
 		 */
 		remaining = tp->rack.rtt_us + reo_wnd -
 			    tcp_stamp_us_delta(tp->tcp_mstamp, skb->skb_mstamp);
-		if (remaining < 0) {
+		if (remaining <= 0) {
 			tcp_rack_mark_skb_lost(sk, skb);
 			list_del_init(&skb->tcp_tsorted_anchor);
 		} else {
-			/* Record maximum wait time (+1 to avoid 0) */
-			*reo_timeout = max_t(u32, *reo_timeout, 1 + remaining);
+			/* Record maximum wait time */
+			*reo_timeout = max_t(u32, *reo_timeout, remaining);
 		}
 	}
 }
-- 
2.15.1.424.g9478a66081-goog