[PATCH net-next 2/3] tcp: move tcp_rack_update_reo_wnd() to tcp_input.c
From: Eric Dumazet <edumazet@google.com>
Date: 2026-01-27 03:21:52
Subsystem:
networking [general], networking [tcp], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Neal Cardwell, Linus Torvalds
tcp_rack_update_reo_wnd() is called only once from tcp_ack() Move it to tcp_input.c so that it can be inlined by the compiler to save space and cpu cycles. $ scripts/bloat-o-meter -t vmlinux.old vmlinux.new add/remove: 0/2 grow/shrink: 1/0 up/down: 110/-153 (-43) Function old new delta tcp_ack 5631 5741 +110 __pfx_tcp_rack_update_reo_wnd 16 - -16 tcp_rack_update_reo_wnd 137 - -137 Total: Before=22572723, After=22572680, chg -0.00% Signed-off-by: Eric Dumazet <edumazet@google.com> --- include/net/tcp.h | 1 - net/ipv4/tcp_input.c | 43 +++++++++++++++++++++++++++++++++++++++++ net/ipv4/tcp_recovery.c | 43 ----------------------------------------- 3 files changed, 43 insertions(+), 44 deletions(-)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index efff433de9a4..a4d9f263ea68 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h@@ -2517,7 +2517,6 @@ extern bool tcp_rack_mark_lost(struct sock *sk); extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq, u64 xmit_time); extern void tcp_rack_reo_timeout(struct sock *sk); -extern void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs); /* tcp_plb.c */
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index f2fafba95705..d504a9a9b6ec 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c@@ -4149,6 +4149,49 @@ static u32 tcp_newly_delivered(struct sock *sk, u32 prior_delivered, return delivered; } +/* Updates the RACK's reo_wnd based on DSACK and no. of recoveries. + * + * If a DSACK is received that seems like it may have been due to reordering + * triggering fast recovery, increment reo_wnd by min_rtt/4 (upper bounded + * by srtt), since there is possibility that spurious retransmission was + * due to reordering delay longer than reo_wnd. + * + * Persist the current reo_wnd value for TCP_RACK_RECOVERY_THRESH (16) + * no. of successful recoveries (accounts for full DSACK-based loss + * recovery undo). After that, reset it to default (min_rtt/4). + * + * At max, reo_wnd is incremented only once per rtt. So that the new + * DSACK on which we are reacting, is due to the spurious retx (approx) + * after the reo_wnd has been updated last time. + * + * reo_wnd is tracked in terms of steps (of min_rtt/4), rather than + * absolute value to account for change in rtt. + */ +static void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs) +{ + struct tcp_sock *tp = tcp_sk(sk); + + if ((READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_recovery) & + TCP_RACK_STATIC_REO_WND) || + !rs->prior_delivered) + return; + + /* Disregard DSACK if a rtt has not passed since we adjusted reo_wnd */ + if (before(rs->prior_delivered, tp->rack.last_delivered)) + tp->rack.dsack_seen = 0; + + /* Adjust the reo_wnd if update is pending */ + if (tp->rack.dsack_seen) { + tp->rack.reo_wnd_steps = min_t(u32, 0xFF, + tp->rack.reo_wnd_steps + 1); + tp->rack.dsack_seen = 0; + tp->rack.last_delivered = tp->delivered; + tp->rack.reo_wnd_persist = TCP_RACK_RECOVERY_THRESH; + } else if (!tp->rack.reo_wnd_persist) { + tp->rack.reo_wnd_steps = 1; + } +} + /* This routine deals with incoming acks, but not outgoing ones. */ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) {
diff --git a/net/ipv4/tcp_recovery.c b/net/ipv4/tcp_recovery.c
index c52fd3254b6e..40732b84771e 100644
--- a/net/ipv4/tcp_recovery.c
+++ b/net/ipv4/tcp_recovery.c@@ -166,49 +166,6 @@ void tcp_rack_reo_timeout(struct sock *sk) tcp_rearm_rto(sk); } -/* Updates the RACK's reo_wnd based on DSACK and no. of recoveries. - * - * If a DSACK is received that seems like it may have been due to reordering - * triggering fast recovery, increment reo_wnd by min_rtt/4 (upper bounded - * by srtt), since there is possibility that spurious retransmission was - * due to reordering delay longer than reo_wnd. - * - * Persist the current reo_wnd value for TCP_RACK_RECOVERY_THRESH (16) - * no. of successful recoveries (accounts for full DSACK-based loss - * recovery undo). After that, reset it to default (min_rtt/4). - * - * At max, reo_wnd is incremented only once per rtt. So that the new - * DSACK on which we are reacting, is due to the spurious retx (approx) - * after the reo_wnd has been updated last time. - * - * reo_wnd is tracked in terms of steps (of min_rtt/4), rather than - * absolute value to account for change in rtt. - */ -void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs) -{ - struct tcp_sock *tp = tcp_sk(sk); - - if ((READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_recovery) & - TCP_RACK_STATIC_REO_WND) || - !rs->prior_delivered) - return; - - /* Disregard DSACK if a rtt has not passed since we adjusted reo_wnd */ - if (before(rs->prior_delivered, tp->rack.last_delivered)) - tp->rack.dsack_seen = 0; - - /* Adjust the reo_wnd if update is pending */ - if (tp->rack.dsack_seen) { - tp->rack.reo_wnd_steps = min_t(u32, 0xFF, - tp->rack.reo_wnd_steps + 1); - tp->rack.dsack_seen = 0; - tp->rack.last_delivered = tp->delivered; - tp->rack.reo_wnd_persist = TCP_RACK_RECOVERY_THRESH; - } else if (!tp->rack.reo_wnd_persist) { - tp->rack.reo_wnd_steps = 1; - } -} - /* RFC6582 NewReno recovery for non-SACK connection. It simply retransmits * the next unacked packet upon receiving * a) three or more DUPACKs to start the fast recovery
--
2.53.0.rc1.217.geba53bf80e-goog