[PATCH v1 net-next 1/1] tcp: Replace min_tso_segs() with tso_segs() CC callback for TCP Prague
From: <hidden>
Date: 2026-06-13 08:08:41
Also in:
bpf
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [selftests] (test runners & infrastructure), kernel selftest framework, networking [general], networking [tcp], the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Shuah Khan, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Neal Cardwell, Linus Torvalds
From: Chia-Yu Chang <redacted> This patch replaces existing min_tso_segs() with tso_segs() CC callbak for CC algorithm to provides explicit tso segment number of each data burst and overrides tcp_tso_autosize(). No functional change. Signed-off-by: Ilpo Järvinen <ij@kernel.org> Signed-off-by: Chia-Yu Chang <redacted> --- include/net/tcp.h | 7 +++++-- net/ipv4/bpf_tcp_ca.c | 4 ++-- net/ipv4/tcp_bbr.c | 14 +++++++++++--- net/ipv4/tcp_output.c | 12 ++++++------ tools/testing/selftests/bpf/progs/tcp_ca_kfunc.c | 8 ++++---- 5 files changed, 28 insertions(+), 17 deletions(-)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index f063eccbbba3..34d370ea9ceb 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h@@ -824,6 +824,9 @@ unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu); unsigned int tcp_current_mss(struct sock *sk); u32 tcp_clamp_probe0_to_user_timeout(const struct sock *sk, u32 when); +u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now, + int min_tso_segs); + /* Bound MSS / TSO packet size with the half of the window */ static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize) {
@@ -1361,8 +1364,8 @@ struct tcp_congestion_ops { /* hook for packet ack accounting (optional) */ void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample); - /* override sysctl_tcp_min_tso_segs (optional) */ - u32 (*min_tso_segs)(struct sock *sk); + /* override tcp_tso_autosize (optional)*/ + u32 (*tso_segs)(struct sock *sk, u32 mss_now); /* new value of cwnd after loss (required) */ u32 (*undo_cwnd)(struct sock *sk);
diff --git a/net/ipv4/bpf_tcp_ca.c b/net/ipv4/bpf_tcp_ca.c
index 791e15063237..ed4fea98dfde 100644
--- a/net/ipv4/bpf_tcp_ca.c
+++ b/net/ipv4/bpf_tcp_ca.c@@ -284,7 +284,7 @@ static void bpf_tcp_ca_pkts_acked(struct sock *sk, const struct ack_sample *samp { } -static u32 bpf_tcp_ca_min_tso_segs(struct sock *sk) +static u32 bpf_tcp_ca_tso_segs(struct sock *sk, u32 mss_now) { return 0; }
@@ -320,7 +320,7 @@ static struct tcp_congestion_ops __bpf_ops_tcp_congestion_ops = { .cwnd_event_tx_start = bpf_tcp_ca_cwnd_event_tx_start, .in_ack_event = bpf_tcp_ca_in_ack_event, .pkts_acked = bpf_tcp_ca_pkts_acked, - .min_tso_segs = bpf_tcp_ca_min_tso_segs, + .tso_segs = bpf_tcp_ca_tso_segs, .cong_control = bpf_tcp_ca_cong_control, .undo_cwnd = bpf_tcp_ca_undo_cwnd, .sndbuf_expand = bpf_tcp_ca_sndbuf_expand,
diff --git a/net/ipv4/tcp_bbr.c b/net/ipv4/tcp_bbr.c
index 82378a2bfd1e..15536564246c 100644
--- a/net/ipv4/tcp_bbr.c
+++ b/net/ipv4/tcp_bbr.c@@ -297,11 +297,19 @@ static void bbr_set_pacing_rate(struct sock *sk, u32 bw, int gain) } /* override sysctl_tcp_min_tso_segs */ -__bpf_kfunc static u32 bbr_min_tso_segs(struct sock *sk) +static u32 bbr_min_tso_segs(struct sock *sk) { return READ_ONCE(sk->sk_pacing_rate) < (bbr_min_tso_rate >> 3) ? 1 : 2; } +__bpf_kfunc static u32 bbr_tso_segs(struct sock *sk, u32 mss_now) +{ + u32 min_tso; + + min_tso = bbr_min_tso_segs(sk); + return tcp_tso_autosize(sk, mss_now, min_tso); +} + static u32 bbr_tso_segs_goal(struct sock *sk) { struct tcp_sock *tp = tcp_sk(sk);
@@ -1151,7 +1159,7 @@ static struct tcp_congestion_ops tcp_bbr_cong_ops __read_mostly = { .undo_cwnd = bbr_undo_cwnd, .cwnd_event_tx_start = bbr_cwnd_event_tx_start, .ssthresh = bbr_ssthresh, - .min_tso_segs = bbr_min_tso_segs, + .tso_segs = bbr_tso_segs, .get_info = bbr_get_info, .set_state = bbr_set_state, };
@@ -1163,7 +1171,7 @@ BTF_ID_FLAGS(func, bbr_sndbuf_expand) BTF_ID_FLAGS(func, bbr_undo_cwnd) BTF_ID_FLAGS(func, bbr_cwnd_event_tx_start) BTF_ID_FLAGS(func, bbr_ssthresh) -BTF_ID_FLAGS(func, bbr_min_tso_segs) +BTF_ID_FLAGS(func, bbr_tso_segs) BTF_ID_FLAGS(func, bbr_set_state) BTF_KFUNCS_END(tcp_bbr_check_kfunc_ids)
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 26dd751ec72a..14fde0aa14be 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c@@ -2253,8 +2253,8 @@ static bool tcp_nagle_check(bool partial, const struct tcp_sock *tp, * for every 2^9 usec (aka 512 us) of RTT, so that the RTT-based allowance * is below 1500 bytes after 6 * ~500 usec = 3ms. */ -static u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now, - int min_tso_segs) +u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now, + int min_tso_segs) { unsigned long bytes; u32 r;
@@ -2278,11 +2278,11 @@ static u32 tcp_tso_segs(struct sock *sk, unsigned int mss_now) const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; u32 min_tso, tso_segs; - min_tso = ca_ops->min_tso_segs ? - ca_ops->min_tso_segs(sk) : - READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs); + min_tso = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs); - tso_segs = tcp_tso_autosize(sk, mss_now, min_tso); + tso_segs = ca_ops->tso_segs ? + ca_ops->tso_segs(sk, mss_now) : + tcp_tso_autosize(sk, mss_now, min_tso); return min_t(u32, tso_segs, sk->sk_gso_max_segs); }
diff --git a/tools/testing/selftests/bpf/progs/tcp_ca_kfunc.c b/tools/testing/selftests/bpf/progs/tcp_ca_kfunc.c
index 0a3e9d35bf6f..58262e490336 100644
--- a/tools/testing/selftests/bpf/progs/tcp_ca_kfunc.c
+++ b/tools/testing/selftests/bpf/progs/tcp_ca_kfunc.c@@ -10,7 +10,7 @@ extern u32 bbr_sndbuf_expand(struct sock *sk) __ksym; extern u32 bbr_undo_cwnd(struct sock *sk) __ksym; extern void bbr_cwnd_event_tx_start(struct sock *sk) __ksym; extern u32 bbr_ssthresh(struct sock *sk) __ksym; -extern u32 bbr_min_tso_segs(struct sock *sk) __ksym; +extern u32 bbr_tso_segs(struct sock *sk, u32 mss_now) __ksym; extern void bbr_set_state(struct sock *sk, u8 new_state) __ksym; extern void dctcp_init(struct sock *sk) __ksym;
@@ -90,9 +90,9 @@ u32 BPF_PROG(ssthresh, struct sock *sk) } SEC("struct_ops") -u32 BPF_PROG(min_tso_segs, struct sock *sk) +u32 BPF_PROG(tso_segs, struct sock *sk, u32 mss_now) { - return bbr_min_tso_segs(sk); + return bbr_tso_segs(sk, mss_now); } SEC("struct_ops")
@@ -120,7 +120,7 @@ struct tcp_congestion_ops tcp_ca_kfunc = { .cwnd_event = (void *)cwnd_event, .cwnd_event_tx_start = (void *)cwnd_event_tx_start, .ssthresh = (void *)ssthresh, - .min_tso_segs = (void *)min_tso_segs, + .tso_segs = (void *)tso_segs, .set_state = (void *)set_state, .pkts_acked = (void *)pkts_acked, .name = "tcp_ca_kfunc",
--
2.34.1