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linux/debian/patches/misc-bbr3/0014-net-tcp_bbr-v2-introduce-is_acking_tlp_retrans_seq-i.patch

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From cab22a8e2e87870e8334a12ffcd0ba04ea81126f Mon Sep 17 00:00:00 2001
From: Neal Cardwell <ncardwell@google.com>
Date: Mon, 21 Sep 2020 14:46:26 -0400
Subject: [PATCH 14/19] net-tcp_bbr: v2: introduce is_acking_tlp_retrans_seq
into rate_sample
Introduce is_acking_tlp_retrans_seq into rate_sample. This bool will
export to the CC module the knowledge of whether the current ACK
matched a TLP retransmit.
Note that when this bool is true, we cannot yet tell (in general) whether
this ACK is for the original or the TLP retransmit.
Effort: net-tcp_bbr
Change-Id: I2e6494332167e75efcbdc99bd5c119034e9c39b4
Signed-off-by: Alexandre Frade <kernel@xanmod.org>
---
include/net/tcp.h | 1 +
net/ipv4/tcp_input.c | 12 +++++++++---
2 files changed, 10 insertions(+), 3 deletions(-)
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1161,6 +1161,7 @@ struct rate_sample {
u32 last_end_seq; /* end_seq of most recently ACKed packet */
bool is_app_limited; /* is sample from packet with bubble in pipe? */
bool is_retrans; /* is sample from retransmission? */
+ bool is_acking_tlp_retrans_seq; /* ACKed a TLP retransmit sequence? */
bool is_ack_delayed; /* is this (likely) a delayed ACK? */
bool is_ece; /* did this ACK have ECN marked? */
};
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3842,7 +3842,8 @@ static void tcp_replace_ts_recent(struct
/* This routine deals with acks during a TLP episode and ends an episode by
* resetting tlp_high_seq. Ref: TLP algorithm in draft-ietf-tcpm-rack
*/
-static void tcp_process_tlp_ack(struct sock *sk, u32 ack, int flag)
+static void tcp_process_tlp_ack(struct sock *sk, u32 ack, int flag,
+ struct rate_sample *rs)
{
struct tcp_sock *tp = tcp_sk(sk);
@@ -3870,6 +3871,11 @@ static void tcp_process_tlp_ack(struct s
FLAG_NOT_DUP | FLAG_DATA_SACKED))) {
/* Pure dupack: original and TLP probe arrived; no loss */
tp->tlp_high_seq = 0;
+ } else {
+ /* This ACK matches a TLP retransmit. We cannot yet tell if
+ * this ACK is for the original or the TLP retransmit.
+ */
+ rs->is_acking_tlp_retrans_seq = 1;
}
}
@@ -4053,7 +4059,7 @@ static int tcp_ack(struct sock *sk, cons
tcp_rack_update_reo_wnd(sk, &rs);
if (tp->tlp_high_seq)
- tcp_process_tlp_ack(sk, ack, flag);
+ tcp_process_tlp_ack(sk, ack, flag, &rs);
if (tcp_ack_is_dubious(sk, flag)) {
if (!(flag & (FLAG_SND_UNA_ADVANCED |
@@ -4097,7 +4103,7 @@ no_queue:
tcp_ack_probe(sk);
if (tp->tlp_high_seq)
- tcp_process_tlp_ack(sk, ack, flag);
+ tcp_process_tlp_ack(sk, ack, flag, &rs);
return 1;
old_ack: