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Message-Id: <20250703051728.37431-9-chia-yu.chang@nokia-bell-labs.com>
Date: Thu, 3 Jul 2025 07:17:21 +0200
From: chia-yu.chang@...ia-bell-labs.com
To: pabeni@...hat.com,
edumazet@...gle.com,
linux-doc@...r.kernel.org,
corbet@....net,
horms@...nel.org,
dsahern@...nel.org,
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bpf@...r.kernel.org,
netdev@...r.kernel.org,
dave.taht@...il.com,
jhs@...atatu.com,
kuba@...nel.org,
stephen@...workplumber.org,
xiyou.wangcong@...il.com,
jiri@...nulli.us,
davem@...emloft.net,
andrew+netdev@...n.ch,
donald.hunter@...il.com,
ast@...erby.net,
liuhangbin@...il.com,
shuah@...nel.org,
linux-kselftest@...r.kernel.org,
ij@...nel.org,
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g.white@...lelabs.com,
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mirja.kuehlewind@...csson.com,
cheshire@...le.com,
rs.ietf@....at,
Jason_Livingood@...cast.com,
vidhi_goel@...le.com
Cc: Chia-Yu Chang <chia-yu.chang@...ia-bell-labs.com>
Subject: [PATCH v11 net-next 08/15] tcp: accecn: add AccECN rx byte counters
From: Ilpo Järvinen <ij@...nel.org>
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; /* 2640 4 */
u32 received_ce; /* 2644 4 */
u32 app_limited; /* 2648 4 */
u32 rcv_wnd; /* 2652 4 */
struct tcp_options_received rx_opt; /* 2656 24 */
__cacheline_group_end__tcp_sock_write_txrx[0]; /* 2680 0 */
[...]
/* size: 3264, cachelines: 51, members: 169 */
}
[AFTER THIS PATCH]
struct tcp_sock {
[...]
u32 delivered_ce; /* 2640 4 */
u32 received_ce; /* 2644 4 */
u32 received_ecn_bytes[3];/* 2648 12 */
u32 app_limited; /* 2660 4 */
u32 rcv_wnd; /* 2664 4 */
struct tcp_options_received rx_opt; /* 2668 24 */
__cacheline_group_end__tcp_sock_write_txrx[0]; /* 2692 0 */
/* XXX 4 bytes hole, try to pack */
[...]
/* size: 3264, cachelines: 51, members: 170 */
}
Signed-off-by: Ilpo Järvinen <ij@...nel.org>
Signed-off-by: Neal Cardwell <ncardwell@...gle.com>
Co-developed-by: Chia-Yu Chang <chia-yu.chang@...ia-bell-labs.com>
Signed-off-by: Chia-Yu Chang <chia-yu.chang@...ia-bell-labs.com>
---
v8:
- Add new helper function tcp_ecn_received_counters_payload()
---
.../networking/net_cachelines/tcp_sock.rst | 1 +
include/linux/tcp.h | 4 +++
include/net/tcp.h | 3 +++
include/net/tcp_ecn.h | 26 ++++++++++++++++++-
net/ipv4/syncookies.c | 1 +
net/ipv4/tcp.c | 3 ++-
net/ipv4/tcp_input.c | 7 ++---
net/ipv4/tcp_minisocks.c | 2 +-
net/ipv6/syncookies.c | 1 +
9 files changed, 42 insertions(+), 6 deletions(-)
diff --git a/Documentation/networking/net_cachelines/tcp_sock.rst b/Documentation/networking/net_cachelines/tcp_sock.rst
index 22ac668fe6c7..804480d39132 100644
--- a/Documentation/networking/net_cachelines/tcp_sock.rst
+++ b/Documentation/networking/net_cachelines/tcp_sock.rst
@@ -102,6 +102,7 @@ u32 prr_out read_mostly read_m
u32 delivered read_mostly read_write tcp_rate_skb_sent, tcp_newly_delivered(tx);tcp_ack, tcp_rate_gen, tcp_clean_rtx_queue (rx)
u32 delivered_ce read_mostly read_write tcp_rate_skb_sent(tx);tcp_rate_gen(rx)
u32 received_ce read_mostly read_write
+u32[3] received_ecn_bytes read_mostly read_write
u8:4 received_ce_pending read_mostly read_write
u8:2 syn_ect_snt write_mostly read_write
u8:2 syn_ect_rcv read_mostly read_write
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 1d8301f2883c..0c2331e186e8 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.h b/include/net/tcp.h
index 61b103633da4..0d8e1a676dad 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -971,6 +971,9 @@ static inline u32 tcp_rsk_tsval(const struct tcp_request_sock *treq)
* See draft-ietf-tcpm-accurate-ecn for the latest values.
*/
#define TCP_ACCECN_CEP_INIT_OFFSET 5
+#define TCP_ACCECN_E1B_INIT_OFFSET 1
+#define TCP_ACCECN_E0B_INIT_OFFSET 1
+#define TCP_ACCECN_CEB_INIT_OFFSET 0
/* State flags for sacked in struct tcp_skb_cb */
enum tcp_skb_cb_sacked_flags {
diff --git a/include/net/tcp_ecn.h b/include/net/tcp_ecn.h
index 7ac68cb70ef3..68e392ba2f9e 100644
--- a/include/net/tcp_ecn.h
+++ b/include/net/tcp_ecn.h
@@ -176,7 +176,7 @@ 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);
@@ -196,9 +196,21 @@ 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;
}
}
+
+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).
@@ -242,10 +254,22 @@ 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 */
diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index e0c1e951c53c..569befcf021b 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -12,6 +12,7 @@
#include <linux/export.h>
#include <net/secure_seq.h>
#include <net/tcp.h>
+#include <net/tcp_ecn.h>
#include <net/route.h>
static siphash_aligned_key_t syncookie_secret[2];
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 0548c74458c6..237435927b9a 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -5121,6 +5121,7 @@ static void __init tcp_struct_check(void)
CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_write_txrx, delivered);
CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_write_txrx, delivered_ce);
CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_write_txrx, received_ce);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_write_txrx, received_ecn_bytes);
CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_write_txrx, app_limited);
CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_write_txrx, rcv_wnd);
CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_write_txrx, rx_opt);
@@ -5128,7 +5129,7 @@ static void __init tcp_struct_check(void)
/* 32bit arches with 8byte alignment on u64 fields might need padding
* before tcp_clock_cache.
*/
- CACHELINE_ASSERT_GROUP_SIZE(struct tcp_sock, tcp_sock_write_txrx, 95 + 4);
+ CACHELINE_ASSERT_GROUP_SIZE(struct tcp_sock, tcp_sock_write_txrx, 107 + 4);
/* RX read-write hotpath cache lines */
CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_write_rx, bytes_received);
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 7ccfde9bcfda..eea790295e54 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -6138,7 +6138,7 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb)
flag |= __tcp_replace_ts_recent(tp,
delta);
- tcp_ecn_received_counters(sk, skb);
+ tcp_ecn_received_counters(sk, skb, 0);
/* We know that such packets are checksummed
* on entry.
@@ -6184,7 +6184,8 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb)
/* Bulk data transfer: receiver */
tcp_cleanup_skb(skb);
__skb_pull(skb, tcp_header_len);
- tcp_ecn_received_counters(sk, skb);
+ tcp_ecn_received_counters(sk, skb,
+ len - tcp_header_len);
eaten = tcp_queue_rcv(sk, skb, &fragstolen);
tcp_event_data_recv(sk, skb);
@@ -6231,7 +6232,7 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb)
tcp_accecn_third_ack(sk, skb, tp->syn_ect_snt);
tcp_fast_path_on(tp);
}
- tcp_ecn_received_counters(sk, skb);
+ tcp_ecn_received_counters_payload(sk, skb);
reason = tcp_ack(sk, skb, FLAG_SLOWPATH | FLAG_UPDATE_TS_RECENT);
if ((int)reason < 0) {
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 845b1c81b3b0..0a0ee33e38ad 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -473,7 +473,7 @@ static void tcp_ecn_openreq_child(struct sock *sk,
tcp_ecn_mode_set(tp, TCP_ECN_MODE_ACCECN);
tp->syn_ect_snt = treq->syn_ect_snt;
tcp_accecn_third_ack(sk, skb, treq->syn_ect_snt);
- tcp_ecn_received_counters(sk, skb);
+ tcp_ecn_received_counters_payload(sk, skb);
} else {
tcp_ecn_mode_set(tp, inet_rsk(req)->ecn_ok ?
TCP_ECN_MODE_RFC3168 :
diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
index f0b87a3268ae..7e007f013ec8 100644
--- a/net/ipv6/syncookies.c
+++ b/net/ipv6/syncookies.c
@@ -16,6 +16,7 @@
#include <net/secure_seq.h>
#include <net/ipv6.h>
#include <net/tcp.h>
+#include <net/tcp_ecn.h>
#define COOKIEBITS 24 /* Upper bits store count */
#define COOKIEMASK (((__u32)1 << COOKIEBITS) - 1)
--
2.34.1
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