tcp: fix FRTO undo on cumulative ACK of SACKed range
On processing cumulative ACKs, the FRTO code was not checking the
SACKed bit, meaning that there could be a spurious FRTO undo on a
cumulative ACK of a previously SACKed skb.
The FRTO code should only consider a cumulative ACK to indicate that
an original/unretransmitted skb is newly ACKed if the skb was not yet
SACKed.
The effect of the spurious FRTO undo would typically be to make the
connection think that all previously-sent packets were in flight when
they really weren't, leading to a stall and an RTO.
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Fixes: e33099f96d
("tcp: implement RFC5682 F-RTO")
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Родитель
0c36820e2a
Коммит
666b805150
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@ -3105,10 +3105,11 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
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if (!first_ackt.v64)
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first_ackt = last_ackt;
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if (!(sacked & TCPCB_SACKED_ACKED))
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if (!(sacked & TCPCB_SACKED_ACKED)) {
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reord = min(pkts_acked, reord);
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if (!after(scb->end_seq, tp->high_seq))
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flag |= FLAG_ORIG_SACK_ACKED;
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if (!after(scb->end_seq, tp->high_seq))
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flag |= FLAG_ORIG_SACK_ACKED;
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}
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}
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if (sacked & TCPCB_SACKED_ACKED)
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