60 lines
2.0 KiB
Diff
60 lines
2.0 KiB
Diff
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From 99e86f904f246ae9ec7a13d1b920eaf4a8c2d47b Mon Sep 17 00:00:00 2001
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From: Adithya Abraham Philip <abrahamphilip@google.com>
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Date: Fri, 11 Jun 2021 21:56:10 +0000
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Subject: [PATCH 17/19] net-tcp_bbr: v3: ensure ECN-enabled BBR flows set ECT
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on retransmits
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Adds a new flag TCP_ECN_ECT_PERMANENT that is used by CCAs to
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indicate that retransmitted packets and pure ACKs must have the
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ECT bit set. This is necessary for BBR, which when using
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ECN expects ECT to be set even on retransmitted packets and ACKs.
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Previous to this addition of TCP_ECN_ECT_PERMANENT, CCAs which can use
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ECN but don't "need" it did not have a way to indicate that ECT should
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be set on retransmissions/ACKs.
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Signed-off-by: Adithya Abraham Philip <abrahamphilip@google.com>
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Signed-off-by: Neal Cardwell <ncardwell@google.com>
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Change-Id: I8b048eaab35e136fe6501ef6cd89fd9faa15e6d2
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Signed-off-by: Alexandre Frade <kernel@xanmod.org>
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---
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include/net/tcp.h | 1 +
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net/ipv4/tcp_bbr.c | 3 +++
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net/ipv4/tcp_output.c | 3 ++-
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3 files changed, 6 insertions(+), 1 deletion(-)
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--- a/include/net/tcp.h
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+++ b/include/net/tcp.h
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@@ -376,6 +376,7 @@ static inline void tcp_dec_quickack_mode
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#define TCP_ECN_DEMAND_CWR 4
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#define TCP_ECN_SEEN 8
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#define TCP_ECN_LOW 16
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+#define TCP_ECN_ECT_PERMANENT 32
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enum tcp_tw_status {
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TCP_TW_SUCCESS = 0,
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--- a/net/ipv4/tcp_bbr.c
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+++ b/net/ipv4/tcp_bbr.c
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@@ -2151,6 +2151,9 @@ __bpf_kfunc static void bbr_init(struct
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bbr->plb.pause_until = 0;
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tp->fast_ack_mode = bbr_fast_ack_mode ? 1 : 0;
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+
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+ if (bbr_can_use_ecn(sk))
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+ tp->ecn_flags |= TCP_ECN_ECT_PERMANENT;
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}
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/* BBR marks the current round trip as a loss round. */
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--- a/net/ipv4/tcp_output.c
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+++ b/net/ipv4/tcp_output.c
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@@ -390,7 +390,8 @@ static void tcp_ecn_send(struct sock *sk
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th->cwr = 1;
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skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
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}
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- } else if (!tcp_ca_needs_ecn(sk)) {
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+ } else if (!(tp->ecn_flags & TCP_ECN_ECT_PERMANENT) &&
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+ !tcp_ca_needs_ecn(sk)) {
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/* ACK or retransmitted segment: clear ECT|CE */
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INET_ECN_dontxmit(sk);
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}
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