From 9a011277445583bab002fbf5043fab0ea03dc5dd Mon Sep 17 00:00:00 2001 From: Ilpo Järvinen Date: Tue, 16 Sep 2025 10:24:27 +0200 Subject: tcp: accecn: add AccECN rx byte counters MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit These three byte counters track IP ECN field payload byte sums for all arriving (acceptable) packets for ECT0, ECT1, and CE. The AccECN option (added by a later patch in the series) echoes these counters back to sender side; therefore, it is placed within the group of tcp_sock_write_txrx. Below are the pahole outcomes before and after this patch, in which the group size of tcp_sock_write_txrx is increased from 95 + 4 to 107 + 4 and an extra 4-byte hole is created but will be exploited in later patches: [BEFORE THIS PATCH] struct tcp_sock { [...] u32 delivered_ce; /* 2576 4 */ u32 received_ce; /* 2580 4 */ u32 app_limited; /* 2584 4 */ u32 rcv_wnd; /* 2588 4 */ struct tcp_options_received rx_opt; /* 2592 24 */ __cacheline_group_end__tcp_sock_write_txrx[0]; /* 2616 0 */ [...] /* size: 3200, cachelines: 50, members: 166 */ } [AFTER THIS PATCH] struct tcp_sock { [...] u32 delivered_ce; /* 2576 4 */ u32 received_ce; /* 2580 4 */ u32 received_ecn_bytes[3];/* 2584 12 */ u32 app_limited; /* 2596 4 */ u32 rcv_wnd; /* 2600 4 */ struct tcp_options_received rx_opt; /* 2604 24 */ __cacheline_group_end__tcp_sock_write_txrx[0]; /* 2628 0 */ /* XXX 4 bytes hole, try to pack */ [...] /* size: 3200, cachelines: 50, members: 167 */ } Signed-off-by: Ilpo Järvinen Signed-off-by: Neal Cardwell Co-developed-by: Chia-Yu Chang Signed-off-by: Chia-Yu Chang Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20250916082434.100722-4-chia-yu.chang@nokia-bell-labs.com Signed-off-by: Paolo Abeni --- include/linux/tcp.h | 4 ++++ include/net/tcp_ecn.h | 29 ++++++++++++++++++++++++++++- 2 files changed, 32 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/tcp.h b/include/linux/tcp.h index b8432bed546d..012d01347b3c 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -306,6 +306,10 @@ struct tcp_sock { u32 delivered; /* Total data packets delivered incl. rexmits */ u32 delivered_ce; /* Like the above but only ECE marked packets */ u32 received_ce; /* Like the above but for rcvd CE marked pkts */ + u32 received_ecn_bytes[3]; /* received byte counters for three ECN + * types: INET_ECN_ECT_1, INET_ECN_ECT_0, + * and INET_ECN_CE + */ u32 app_limited; /* limited until "delivered" reaches this val */ u32 rcv_wnd; /* Current receiver window */ /* diff --git a/include/net/tcp_ecn.h b/include/net/tcp_ecn.h index da0b355418bd..1a41a459aa07 100644 --- a/include/net/tcp_ecn.h +++ b/include/net/tcp_ecn.h @@ -171,7 +171,7 @@ static inline void tcp_accecn_third_ack(struct sock *sk, /* Updates Accurate ECN received counters from the received IP ECN field */ static inline void tcp_ecn_received_counters(struct sock *sk, - const struct sk_buff *skb) + const struct sk_buff *skb, u32 len) { u8 ecnfield = TCP_SKB_CB(skb)->ip_dsfield & INET_ECN_MASK; u8 is_ce = INET_ECN_is_ce(ecnfield); @@ -191,9 +191,24 @@ static inline void tcp_ecn_received_counters(struct sock *sk, tp->received_ce += pcount; tp->received_ce_pending = min(tp->received_ce_pending + pcount, 0xfU); + + if (len > 0) + tp->received_ecn_bytes[ecnfield - 1] += len; } } +/* AccECN specification, 2.2: [...] A Data Receiver maintains four counters + * initialized at the start of the half-connection. [...] These byte counters + * reflect only the TCP payload length, excluding TCP header and TCP options. + */ +static inline void tcp_ecn_received_counters_payload(struct sock *sk, + const struct sk_buff *skb) +{ + const struct tcphdr *th = (const struct tcphdr *)skb->data; + + tcp_ecn_received_counters(sk, skb, skb->len - th->doff * 4); +} + /* AccECN specification, 5.1: [...] a server can determine that it * negotiated AccECN as [...] if the ACK contains an ACE field with * the value 0b010 to 0b111 (decimal 2 to 7). @@ -232,10 +247,22 @@ static inline bool tcp_accecn_syn_requested(const struct tcphdr *th) return ace && ace != 0x3; } +static inline void __tcp_accecn_init_bytes_counters(int *counter_array) +{ + BUILD_BUG_ON(INET_ECN_ECT_1 != 0x1); + BUILD_BUG_ON(INET_ECN_ECT_0 != 0x2); + BUILD_BUG_ON(INET_ECN_CE != 0x3); + + counter_array[INET_ECN_ECT_1 - 1] = 0; + counter_array[INET_ECN_ECT_0 - 1] = 0; + counter_array[INET_ECN_CE - 1] = 0; +} + static inline void tcp_accecn_init_counters(struct tcp_sock *tp) { tp->received_ce = 0; tp->received_ce_pending = 0; + __tcp_accecn_init_bytes_counters(tp->received_ecn_bytes); } /* Used for make_synack to form the ACE flags */ -- cgit v1.2.3