MINOR: quic: quic_loss modifications to support BBR

qc_packet_loss_lookup() aim is to detect the packet losses. This is this function
which must called ->on_pkt_lost() BBR specific callback. It also set
<bytes_lost> passed parameter to the total number of bytes detected as lost upon
an ACK frame receipt for its caller.
Modify qc_release_lost_pkts() to call ->congestion_event() with the send time
from the newest packet detected as lost.
Modify qc_release_lost_pkts() to call ->slow_start() callback only if define
by the congestion control algorithm. This is not the case for BBR.

Author: haproxyFred

include/haproxy/quic_loss.h

@@ -85,7 +85,7 @@ struct quic_pktns *quic_pto_pktns(struct quic_conn *qc,
                                   unsigned int *pto);
 
 void qc_packet_loss_lookup(struct quic_pktns *pktns, struct quic_conn *qc,
-                           struct list *lost_pkts);
+                           struct list *lost_pkts, uint32_t *bytes_lost);
 int qc_release_lost_pkts(struct quic_conn *qc, struct quic_pktns *pktns,
                          struct list *pkts, uint64_t now_us);
 #endif /* USE_QUIC */

src/quic_conn.c

@@ -931,7 +931,7 @@ struct task *qc_process_timer(struct task *task, void *ctx, unsigned int state)
 	if (tick_isset(pktns->tx.loss_time)) {
 		struct list lost_pkts = LIST_HEAD_INIT(lost_pkts);
 
-		qc_packet_loss_lookup(pktns, qc, &lost_pkts);
+		qc_packet_loss_lookup(pktns, qc, &lost_pkts, NULL);
 		if (!LIST_ISEMPTY(&lost_pkts))
 		    tasklet_wakeup(qc->wait_event.tasklet);
 		if (qc_release_lost_pkts(qc, pktns, &lost_pkts, now_ms))

src/quic_loss.c

@@ -1,5 +1,6 @@
 #include <import/eb64tree.h>
 
+#include <haproxy/quic_cc-t.h>
 #include <haproxy/quic_conn-t.h>
 #include <haproxy/quic_loss.h>
 #include <haproxy/quic_tls.h>
@@ -151,7 +152,7 @@ struct quic_pktns *quic_pto_pktns(struct quic_conn *qc,
  * Always succeeds.
  */
 void qc_packet_loss_lookup(struct quic_pktns *pktns, struct quic_conn *qc,
-                           struct list *lost_pkts)
+                           struct list *lost_pkts, uint32_t *bytes_lost)
 {
 	struct eb_root *pkts;
 	struct eb64_node *node;
@@ -213,8 +214,14 @@ void qc_packet_loss_lookup(struct quic_pktns *pktns, struct quic_conn *qc,
 			ql->nb_reordered_pkt++;
 
 		if (tick_is_le(loss_time_limit, now_ms) || reordered) {
+			struct quic_cc *cc = &qc->path->cc;
+
+			if (cc->algo->on_pkt_lost)
+				cc->algo->on_pkt_lost(cc, pkt, pkt->rs.lost);
 			eb64_delete(&pkt->pn_node);
 			LIST_APPEND(lost_pkts, &pkt->list);
+			if (bytes_lost)
+				*bytes_lost += pkt->len;
 			ql->nb_lost_pkt++;
 		}
 		else {
@@ -276,14 +283,17 @@ int qc_release_lost_pkts(struct quic_conn *qc, struct quic_pktns *pktns,
 
 	if (!close) {
 		if (newest_lost) {
+			struct quic_cc *cc = &qc->path->cc;
 			/* Sent a congestion event to the controller */
 			struct quic_cc_event ev = { };
 
 			ev.type = QUIC_CC_EVT_LOSS;
 			ev.loss.time_sent = newest_lost->time_sent;
 			ev.loss.count = tot_lost;
 
-			quic_cc_event(&qc->path->cc, &ev);
+			quic_cc_event(cc, &ev);
+			if (cc->algo->congestion_event)
+			    cc->algo->congestion_event(cc, newest_lost->time_sent);
 		}
 
 		/* If an RTT have been already sampled, <rtt_min> has been set.
@@ -295,7 +305,8 @@ int qc_release_lost_pkts(struct quic_conn *qc, struct quic_pktns *pktns,
 			unsigned int period = newest_lost->time_sent - oldest_lost->time_sent;
 
 			if (quic_loss_persistent_congestion(&qc->path->loss, period,
-							    now_ms, qc->max_ack_delay))
+							    now_ms, qc->max_ack_delay) &&
+			    qc->path->cc.algo->slow_start)
 				qc->path->cc.algo->slow_start(&qc->path->cc);
 		}
 	}