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Message-ID: <20260127032147.3498272-3-edumazet@google.com>
Date: Tue, 27 Jan 2026 03:21:46 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
Cc: Simon Horman <horms@...nel.org>, Neal Cardwell <ncardwell@...gle.com>,
Kuniyuki Iwashima <kuniyu@...gle.com>, netdev@...r.kernel.org, eric.dumazet@...il.com,
Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 2/3] tcp: move tcp_rack_update_reo_wnd() to tcp_input.c
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@...gle.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
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