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authorNeal Cardwell <ncardwell@google.com>2015-04-01 20:26:46 -0400
committerDavid S. Miller <davem@davemloft.net>2015-04-02 16:35:58 -0400
commit666b805150efd62f05810ff0db08f44a2370c937 (patch)
tree265d4aba6edfc0b63a07ba13f2c05eafe4e2ad4f
parent0c36820e2ab7d943ab1188230fdf2149826d33c0 (diff)
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: e33099f96d99c ("tcp: implement RFC5682 F-RTO") Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv4/tcp_input.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index fb4cf8b8e121..f501ac048366 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3105,10 +3105,11 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
if (!first_ackt.v64)
first_ackt = last_ackt;
- if (!(sacked & TCPCB_SACKED_ACKED))
+ if (!(sacked & TCPCB_SACKED_ACKED)) {
reord = min(pkts_acked, reord);
- if (!after(scb->end_seq, tp->high_seq))
- flag |= FLAG_ORIG_SACK_ACKED;
+ if (!after(scb->end_seq, tp->high_seq))
+ flag |= FLAG_ORIG_SACK_ACKED;
+ }
}
if (sacked & TCPCB_SACKED_ACKED)