0043-tcp-export-TCPI_OPT_ECN_LOW-in-tcp_info-tcpi_options.patch

From eb1649fa2040612b10c5c79e142c0700c49ae432 Mon Sep 17 00:00:00 2001
From: Neal Cardwell <ncardwell@google.com>
Date: Sun, 23 Jul 2023 23:25:34 -0400
Subject: [PATCH 18/18] tcp: export TCPI_OPT_ECN_LOW in tcp_info tcpi_options
 field

Analogous to other important ECN information, export TCPI_OPT_ECN_LOW
in tcp_info tcpi_options field.

Signed-off-by: Neal Cardwell <ncardwell@google.com>
Change-Id: I08d8d8c7e8780e6e37df54038ee50301ac5a0320
Signed-off-by: Alexandre Frade <kernel@xanmod.org>
---
 include/uapi/linux/tcp.h | 1 +
 net/ipv4/tcp.c           | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index 879eeb0a084b..77270053a5e3 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -170,6 +170,7 @@ enum tcp_fastopen_client_fail {
 #define TCPI_OPT_ECN		8 /* ECN was negociated at TCP session init */
 #define TCPI_OPT_ECN_SEEN	16 /* we received at least one packet with ECT */
 #define TCPI_OPT_SYN_DATA	32 /* SYN-ACK acked data in SYN sent or rcvd */
+#define TCPI_OPT_ECN_LOW	64 /* Low-latency ECN configured at init */
 
 /*
  * Sender's congestion state indicating normal or abnormal situations
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 3678793e6149..f9c1ca064b50 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3755,6 +3755,8 @@ void tcp_get_info(struct sock *sk, struct tcp_info *info)
 		info->tcpi_options |= TCPI_OPT_ECN;
 	if (tp->ecn_flags & TCP_ECN_SEEN)
 		info->tcpi_options |= TCPI_OPT_ECN_SEEN;
+	if (tp->ecn_flags & TCP_ECN_LOW)
+		info->tcpi_options |= TCPI_OPT_ECN_LOW;
 	if (tp->syn_data_acked)
 		info->tcpi_options |= TCPI_OPT_SYN_DATA;
 
-- 
2.39.2