From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Paolo Abeni <pabeni@redhat.com>,
        Eric Dumazet <edumazet@google.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.15 104/179] mptcp: fix delack timer
Date:   Mon, 29 Nov 2021 19:18:18 +0100
Message-Id: <20211129181722.360957073@linuxfoundation.org>
In-Reply-To: <20211129181718.913038547@linuxfoundation.org>
References: <20211129181718.913038547@linuxfoundation.org>
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From: Eric Dumazet <edumazet@google.com>

[ Upstream commit ee50e67ba0e17b1a1a8d76691d02eadf9e0f392c ]

To compute the rtx timeout schedule_3rdack_retransmission() does multiple
things in the wrong way: srtt_us is measured in usec/8 and the timeout
itself is an absolute value.

Fixes: ec3edaa7ca6ce02f ("mptcp: Add handling of outgoing MP_JOIN requests")
Acked-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <mathew.j.martineau>@linux.intel.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/mptcp/options.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 350348f070700..3fcc2e0c8a5df 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -434,9 +434,10 @@ static void schedule_3rdack_retransmission(struct sock *sk)
 
 	/* reschedule with a timeout above RTT, as we must look only for drop */
 	if (tp->srtt_us)
-		timeout = tp->srtt_us << 1;
+		timeout = usecs_to_jiffies(tp->srtt_us >> (3 - 1));
 	else
 		timeout = TCP_TIMEOUT_INIT;
+	timeout += jiffies;
 
 	WARN_ON_ONCE(icsk->icsk_ack.pending & ICSK_ACK_TIMER);
 	icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
-- 
2.33.0