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-rw-r--r--src/lib/frct.c72
1 files changed, 50 insertions, 22 deletions
diff --git a/src/lib/frct.c b/src/lib/frct.c
index 17fca272..936ca587 100644
--- a/src/lib/frct.c
+++ b/src/lib/frct.c
@@ -55,11 +55,28 @@
/* DSACK seqno sanity: reject reports older/farther than one rcv window. */
#define MAX_DSACK_LAG RQ_SIZE
+/* Signed ns elapsed; negative under concurrent update (no underflow). */
+static __inline__ int64_t ts_age_ns(uint64_t now_ns,
+ uint64_t then_ns)
+{
+ return (int64_t)(now_ns - then_ns);
+}
+
+/* True iff strictly more than thr_ns elapsed since then_ns. */
+static __inline__ bool ts_aged_ns(uint64_t now_ns,
+ uint64_t then_ns,
+ uint64_t thr_ns)
+{
+ return ts_age_ns(now_ns, then_ns) > (int64_t) thr_ns;
+}
+
/* FRCT r-timer: do not retransmit packet older than t_r (from first send). */
-#define RXM_AGED_OUT(t0, now_ns, t_r) (((now_ns) - (t0)) > (uint64_t) (t_r))
+#define RXM_AGED_OUT(t0, now_ns, t_r) \
+ ts_aged_ns((now_ns), (t0), (uint64_t)(t_r))
/* FRCT a-timer: do not (re)transmit ACK after t_a from last data receive. */
-#define ACK_AGED_OUT(act, now_ns, t_a) (((now_ns) - (act)) > (uint64_t) (t_a))
+#define ACK_AGED_OUT(act, now_ns, t_a) \
+ ts_aged_ns((now_ns), (act), (uint64_t)(t_a))
struct sack_args {
uint16_t n;
@@ -855,7 +872,7 @@ static __inline__ bool min_rtt_stale(struct frcti * frcti,
if (mrtt < frcti->min_rtt)
return true;
- return (now_ns - frcti->t_min_rtt) > MIN_RTT_WIN_NS;
+ return ts_aged_ns(now_ns, frcti->t_min_rtt, MIN_RTT_WIN_NS);
}
/* Linux-style windowed-min refresh of RACK.min_RTT. */
@@ -944,10 +961,12 @@ static bool rtt_probe_arm(struct frcti * frcti,
if (!after(frcti->snd_cr.seqno, frcti->snd_cr.lwe))
return false;
- if (now_ns - frcti->t_rcv_rtt <= 2u * (uint64_t) frcti->srtt)
+ if (!ts_aged_ns(now_ns, frcti->t_rcv_rtt,
+ 2u * (uint64_t) frcti->srtt))
return false;
- if (now_ns - frcti->t_snd_probe <= (uint64_t) frcti->srtt)
+ if (!ts_aged_ns(now_ns, frcti->t_snd_probe,
+ (uint64_t) frcti->srtt))
return false;
*probe_id = rttp_alloc_probe(frcti, now_ns, nonce);
@@ -1374,7 +1393,7 @@ static void ack_snd(struct frcti * frcti,
goto out;
}
- diff = (time_t)(now_ns - frcti->snd_cr.act);
+ diff = (time_t) ts_age_ns(now_ns, frcti->snd_cr.act);
if (diff < TICTIME && !frcti->dsack_valid) {
pthread_rwlock_unlock(&frcti->lock);
STAT_BUMP(frcti, ack_supp_rate);
@@ -1500,8 +1519,8 @@ static void ka_snd(struct frcti * frcti)
timeo_ns = (time_t)(frcti->qs_timeout) * MILLION; /* IMM */
rcv_act = LOAD_RELAXED(&frcti->rcv_cr.act);
ka_rcv = LOAD_RELAXED(&frcti->t_ka_rcv);
- rcv_idle = (int64_t)(now_ns - (rcv_act > ka_rcv ? rcv_act : ka_rcv));
- snd_idle = (int64_t)(now_ns - LOAD_RELAXED(&frcti->snd_cr.act));
+ rcv_idle = ts_age_ns(now_ns, rcv_act > ka_rcv ? rcv_act : ka_rcv);
+ snd_idle = ts_age_ns(now_ns, LOAD_RELAXED(&frcti->snd_cr.act));
if (rcv_idle > timeo_ns) {
frct_mark_peer_dead(frcti);
@@ -2582,6 +2601,7 @@ static void frcti_rttp_rcv(struct frcti * frcti,
uint32_t echo_id;
uint8_t nonce[RTTP_NONCE_LEN];
size_t ring_pos;
+ int64_t elapsed;
uint64_t sample;
if (pkt.len < RTTP_PAYLOAD)
@@ -2613,10 +2633,16 @@ static void frcti_rttp_rcv(struct frcti * frcti,
return;
}
- sample = now_ns - frcti->probes[ring_pos].ts;
+ elapsed = ts_age_ns(now_ns, frcti->probes[ring_pos].ts);
frcti->probes[ring_pos].ts = 0;
frcti->t_rcv_rtt = now_ns;
+ if (elapsed <= 0) {
+ pthread_rwlock_unlock(&frcti->lock);
+ return;
+ }
+ sample = (uint64_t) elapsed;
+
/* Clamp probe sample to RTT_CLAMP_MUL * srtt to avoid poisoning. */
if (frcti->srtt > 0)
sample = MIN(sample, (uint64_t) frcti->srtt * RTT_CLAMP_MUL);
@@ -2904,11 +2930,13 @@ static void frcti_ack_rcv(struct frcti * frcti,
frcti->in_recovery = false;
if (rtt_sample_eligible(frcti, p, flags, lwe)) {
- uint64_t mrtt = now_ns - frcti->snd_slots[p].time;
- if (!(flags & FRCT_DATA))
- STAT_BUMP(frcti, ack_rtt);
- rtt_update(frcti, mrtt, now_ns);
- frcti->t_rcv_rtt = now_ns;
+ int64_t mrtt = ts_age_ns(now_ns, frcti->snd_slots[p].time);
+ if (mrtt > 0) {
+ if (!(flags & FRCT_DATA))
+ STAT_BUMP(frcti, ack_rtt);
+ rtt_update(frcti, (time_t) mrtt, now_ns);
+ frcti->t_rcv_rtt = now_ns;
+ }
}
}
@@ -3168,7 +3196,7 @@ static enum frct_act rcv_inact_check(struct frcti * frcti,
struct frct_cr * rcv_cr = &frcti->rcv_cr;
uint64_t cd;
- if (now_ns - rcv_cr->act <= rcv_cr->inact)
+ if (!ts_aged_ns(now_ns, rcv_cr->act, rcv_cr->inact))
return FRCT_ACTIVE;
if (flags & FRCT_DRF) {
@@ -3188,7 +3216,7 @@ static enum frct_act rcv_inact_check(struct frcti * frcti,
/* Pre-DRF: nudge sender with NACK (rate-limited). */
cd = frcti->srtt > 0 ? (uint64_t) frcti->srtt : NACK_COOLDOWN_NS;
- if (now_ns - frcti->t_nack < cd)
+ if (!ts_aged_ns(now_ns, frcti->t_nack, cd))
return FRCT_INACT_DROP;
frcti->t_nack = now_ns;
@@ -3252,7 +3280,7 @@ static bool sack_check(struct frcti * frcti,
/* srtt/8 gate starved recovery under burst loss; floor to save CPU. */
min_gap = (uint64_t) SACK_MIN_GAP_NS;
- if (now_ns - frcti->t_snd_sack < min_gap)
+ if (!ts_aged_ns(now_ns, frcti->t_snd_sack, min_gap))
return false;
out->dsack = false;
@@ -3319,7 +3347,7 @@ static void seqno_rotate(struct frcti * frcti,
{
struct frct_cr * snd_cr = &frcti->snd_cr;
- if (now_ns - snd_cr->act <= snd_cr->inact)
+ if (!ts_aged_ns(now_ns, snd_cr->act, snd_cr->inact))
return;
/* Idle-on-wire ≠ idle e2e: don't orphan in-flight rxm. */
if (snd_cr->seqno != snd_cr->lwe)
@@ -3350,7 +3378,7 @@ static int frcti_snd(struct frcti * frcti,
uint16_t pci_flags = 0;
bool rtx;
uint64_t now_ns;
- uint64_t rcv_idle;
+ int64_t rcv_idle;
uint32_t probe_id = 0;
uint8_t probe_nonce[RTTP_NONCE_LEN] = { 0 };
bool probe;
@@ -3409,9 +3437,9 @@ static int frcti_snd(struct frcti * frcti,
seqno = snd_cr->seqno;
pci->seqno = hton32(seqno);
- rcv_idle = now_ns - rcv_cr->act;
+ rcv_idle = ts_age_ns(now_ns, rcv_cr->act);
- if (rcv_idle < rcv_cr->inact) {
+ if (rcv_idle < (int64_t) rcv_cr->inact) {
pci_flags |= FRCT_FC;
pci->window = hton32(frcti_advert_rwe(frcti));
}
@@ -3424,7 +3452,7 @@ static int frcti_snd(struct frcti * frcti,
frcti->snd_slots[p].time = now_ns;
/* Fresh send clears RTX bits. */
frcti->snd_slots[p].flags = 0;
- if (rcv_idle <= (uint64_t) frcti->t_a) {
+ if (rcv_idle <= (int64_t) frcti->t_a) {
pci_flags |= FRCT_ACK;
pci->ackno = hton32(rcv_cr->lwe);
rcv_cr->seqno = rcv_cr->lwe;
generated by cgit v1.2.3 (git 2.39.1) at 2026-05-23 18:13:32 +0000