This is a note to let you know that I've just added the patch titled
tcp: Fix highest_sack and highest_sack_seq
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tcp-fix-highest_sack-and-highest_sack_seq.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Wed 01 Jan 2020 10:36:29 PM CET
From: Cambda Zhu <cambda@xxxxxxxxxxxxxxxxx>
Date: Fri, 27 Dec 2019 16:52:37 +0800
Subject: tcp: Fix highest_sack and highest_sack_seq
From: Cambda Zhu <cambda@xxxxxxxxxxxxxxxxx>
[ Upstream commit 853697504de043ff0bfd815bd3a64de1dce73dc7 ]
>From commit 50895b9de1d3 ("tcp: highest_sack fix"), the logic about
setting tp->highest_sack to the head of the send queue was removed.
Of course the logic is error prone, but it is logical. Before we
remove the pointer to the highest sack skb and use the seq instead,
we need to set tp->highest_sack to NULL when there is no skb after
the last sack, and then replace NULL with the real skb when new skb
inserted into the rtx queue, because the NULL means the highest sack
seq is tp->snd_nxt. If tp->highest_sack is NULL and new data sent,
the next ACK with sack option will increase tp->reordering unexpectedly.
This patch sets tp->highest_sack to the tail of the rtx queue if
it's NULL and new data is sent. The patch keeps the rule that the
highest_sack can only be maintained by sack processing, except for
this only case.
Fixes: 50895b9de1d3 ("tcp: highest_sack fix")
Signed-off-by: Cambda Zhu <cambda@xxxxxxxxxxxxxxxxx>
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv4/tcp_output.c | 3 +++
1 file changed, 3 insertions(+)
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -60,6 +60,9 @@ static void tcp_event_new_data_sent(stru
__skb_unlink(skb, &sk->sk_write_queue);
tcp_rbtree_insert(&sk->tcp_rtx_queue, skb);
+ if (tp->highest_sack == NULL)
+ tp->highest_sack = skb;
+
tp->packets_out += tcp_skb_pcount(skb);
if (!prior_packets || icsk->icsk_pending == ICSK_TIME_LOSS_PROBE)
tcp_rearm_rto(sk);
Patches currently in stable-queue which might be from cambda@xxxxxxxxxxxxxxxxx are
queue-4.19/tcp-fix-highest_sack-and-highest_sack_seq.patch
