diff options
| author | Neal Cardwell <ncardwell@google.com> | 2015-04-01 20:26:46 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-04-29 10:31:46 +0200 |
| commit | e6250f868ccc8a609c88524a785a6e0d915ad3cb (patch) | |
| tree | a2bce9e1b6981ae2b6406fe0981d2d9f46b0d065 /net | |
| parent | 01f69adac109867f892f12057660d891b34182f6 (diff) | |
| download | lwn-e6250f868ccc8a609c88524a785a6e0d915ad3cb.tar.gz lwn-e6250f868ccc8a609c88524a785a6e0d915ad3cb.zip | |
tcp: fix FRTO undo on cumulative ACK of SACKed range
[ Upstream commit 666b805150efd62f05810ff0db08f44a2370c937 ]
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/tcp_input.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 22917918fa80..9fbd69efa999 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3064,10 +3064,11 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets, if (seq_rtt < 0) { seq_rtt = ca_seq_rtt; } - 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) |