2024-12-10 06:44:25 +03:00
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From 3002091ca590f27c6c7c5966883502c87502e01f Mon Sep 17 00:00:00 2001
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2024-10-29 05:12:06 +03:00
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From: Neal Cardwell <ncardwell@google.com>
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Date: Sun, 7 Jan 2024 21:11:26 -0300
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Subject: [PATCH 11/19] net-tcp: add fast_ack_mode=1: skip rwin check in
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tcp_fast_ack_mode__tcp_ack_snd_check()
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Add logic for an experimental TCP connection behavior, enabled with
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tp->fast_ack_mode = 1, which disables checking the receive window
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before sending an ack in __tcp_ack_snd_check(). If this behavior is
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enabled, the data receiver sends an ACK if the amount of data is >
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RCV.MSS.
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Change-Id: Iaa0a0fd7108221f883137a79d5bfa724f1b096d4
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Signed-off-by: Alexandre Frade <kernel@xanmod.org>
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---
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include/linux/tcp.h | 3 ++-
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net/ipv4/tcp.c | 1 +
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net/ipv4/tcp_cong.c | 1 +
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net/ipv4/tcp_input.c | 5 +++--
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4 files changed, 7 insertions(+), 3 deletions(-)
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--- a/include/linux/tcp.h
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+++ b/include/linux/tcp.h
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@@ -369,7 +369,8 @@ struct tcp_sock {
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u8 compressed_ack;
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u8 dup_ack_counter:2,
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tlp_retrans:1, /* TLP is a retransmission */
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- unused:5;
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+ fast_ack_mode:2, /* which fast ack mode ? */
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+ unused:3;
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u8 thin_lto : 1,/* Use linear timeouts for thin streams */
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fastopen_connect:1, /* FASTOPEN_CONNECT sockopt */
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fastopen_no_cookie:1, /* Allow send/recv SYN+data without a cookie */
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--- a/net/ipv4/tcp.c
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+++ b/net/ipv4/tcp.c
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2024-12-10 06:44:25 +03:00
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@@ -3384,6 +3384,7 @@ int tcp_disconnect(struct sock *sk, int
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2024-10-29 05:12:06 +03:00
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tp->rx_opt.dsack = 0;
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tp->rx_opt.num_sacks = 0;
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tp->rcv_ooopack = 0;
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+ tp->fast_ack_mode = 0;
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/* Clean up fastopen related fields */
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--- a/net/ipv4/tcp_cong.c
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+++ b/net/ipv4/tcp_cong.c
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@@ -237,6 +237,7 @@ void tcp_init_congestion_control(struct
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struct inet_connection_sock *icsk = inet_csk(sk);
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tcp_sk(sk)->prior_ssthresh = 0;
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+ tcp_sk(sk)->fast_ack_mode = 0;
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if (icsk->icsk_ca_ops->init)
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icsk->icsk_ca_ops->init(sk);
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if (tcp_ca_needs_ecn(sk))
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--- a/net/ipv4/tcp_input.c
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+++ b/net/ipv4/tcp_input.c
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2024-12-10 06:44:25 +03:00
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@@ -5770,13 +5770,14 @@ static void __tcp_ack_snd_check(struct s
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2024-10-29 05:12:06 +03:00
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/* More than one full frame received... */
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if (((tp->rcv_nxt - tp->rcv_wup) > inet_csk(sk)->icsk_ack.rcv_mss &&
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+ (tp->fast_ack_mode == 1 ||
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/* ... and right edge of window advances far enough.
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* (tcp_recvmsg() will send ACK otherwise).
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* If application uses SO_RCVLOWAT, we want send ack now if
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* we have not received enough bytes to satisfy the condition.
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*/
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- (tp->rcv_nxt - tp->copied_seq < sk->sk_rcvlowat ||
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- __tcp_select_window(sk) >= tp->rcv_wnd)) ||
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+ (tp->rcv_nxt - tp->copied_seq < sk->sk_rcvlowat ||
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+ __tcp_select_window(sk) >= tp->rcv_wnd))) ||
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/* We ACK each frame or... */
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tcp_in_quickack_mode(sk) ||
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/* Protocol state mandates a one-time immediate ACK */
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