BUG/MINOR: quic: fix subscribe operation

Subscribing was not properly designed between quic-conn and quic MUX
layers. Align this as with in other haproxy components : <subs> field is
moved from the MUX to the quic-conn structure. All mention of qcc MUX is
cleaned up in quic_conn_subscribe()/quic_conn_unsubscribe().

Thanks to this change, ACK reception notification has been simplified.
It's now unnecessary to check for the MUX existence before waking it.
Instead, if <subs> quic-conn field is set, just wake-up the upper layer
tasklet without mentionning MUX. This should probably be extended to
other part in quic-conn code.

This should be backported up to 2.6.

include/haproxy/mux_quic-t.h

@@ -97,7 +97,6 @@ struct qcc {
 	struct list send_retry_list; /* list of qcs eligible to send retry */
 
 	struct wait_event wait_event;  /* To be used if we're waiting for I/Os */
-	struct wait_event *subs;
 
 	struct proxy *proxy;
 

include/haproxy/quic_conn-t.h

@@ -706,6 +706,7 @@ struct quic_conn {
 	int stream_buf_count; /* total count of allocated stream buffers for this connection */
 
 	struct wait_event wait_event;
+	struct wait_event *subs;
 
 	/* MUX */
 	struct qcc *qcc;

src/mux_quic.c

@@ -1990,7 +1990,6 @@ static int qc_init(struct connection *conn, struct proxy *prx,
 
 	LIST_INIT(&qcc->send_retry_list);
 
-	qcc->subs = NULL;
 	qcc->wait_event.tasklet->process = qc_io_cb;
 	qcc->wait_event.tasklet->context = qcc;
 	qcc->wait_event.events = 0;

src/quic_conn.c

@@ -1716,14 +1716,12 @@ static inline void qc_treat_acked_tx_frm(struct quic_conn *qc,
 		qc_release_frm(qc, frm);
 	}
 
-	if (stream_acked && qc->mux_state == QC_MUX_READY) {
+	if (stream_acked) {
-		struct qcc *qcc = qc->qcc;
+		if (qc->subs && qc->subs->events & SUB_RETRY_SEND) {
-
+			tasklet_wakeup(qc->subs->tasklet);
-		if (qcc->subs && qcc->subs->events & SUB_RETRY_SEND) {
+			qc->subs->events &= ~SUB_RETRY_SEND;
-			tasklet_wakeup(qcc->subs->tasklet);
+			if (!qc->subs->events)
-			qcc->subs->events &= ~SUB_RETRY_SEND;
+				qc->subs = NULL;
-			if (!qcc->subs->events)
-				qcc->subs = NULL;
 		}
 	}
  leave:
@@ -4614,15 +4612,12 @@ struct task *qc_process_timer(struct task *task, void *ctx, unsigned int state)
 
 	if (qc->path->in_flight) {
 		pktns = quic_pto_pktns(qc, qc->state >= QUIC_HS_ST_COMPLETE, NULL);
-		if (qc->mux_state == QC_MUX_READY && qc->qcc->subs &&
+		if (qc->subs && qc->subs->events & SUB_RETRY_SEND) {
-		    qc->qcc->subs->events & SUB_RETRY_SEND) {
-			struct qcc *qcc = qc->qcc;
-
 			pktns->tx.pto_probe = QUIC_MAX_NB_PTO_DGRAMS;
-			tasklet_wakeup(qcc->subs->tasklet);
+			tasklet_wakeup(qc->subs->tasklet);
-			qcc->subs->events &= ~SUB_RETRY_SEND;
+			qc->subs->events &= ~SUB_RETRY_SEND;
-			if (!qcc->subs->events)
+			if (!qc->subs->events)
-				qcc->subs = NULL;
+				qc->subs = NULL;
 		}
 		else {
 			qc->flags |= QUIC_FL_CONN_RETRANS_NEEDED;
@@ -4865,6 +4860,7 @@ static struct quic_conn *qc_new_conn(const struct quic_version *qv, int ipv4,
 	 */
 	qc->tid = quic_get_cid_tid(qc->scid.data, l->bind_conf);
 	qc->wait_event.tasklet->tid = qc->tid;
+	qc->subs = NULL;
 
 	if (qc_conn_alloc_ssl_ctx(qc) ||
 	    !quic_conn_init_timer(qc) ||

src/xprt_quic.c

@@ -47,21 +47,24 @@ static void quic_close(struct connection *conn, void *xprt_ctx)
 static int quic_conn_subscribe(struct connection *conn, void *xprt_ctx, int event_type, struct wait_event *es)
 {
 	struct quic_conn *qc = conn->handle.qc;
-	struct qcc *qcc = qc->qcc;
 
 	TRACE_ENTER(QUIC_EV_CONN_SUB, qc);
 
 	BUG_ON(event_type & ~(SUB_RETRY_SEND|SUB_RETRY_RECV));
-	BUG_ON(qcc->subs && qcc->subs != es);
+	BUG_ON(qc->subs && qc->subs != es);
 
 	es->events |= event_type;
-	qcc->subs = es;
+	qc->subs = es;
+
+	/* TODO implement a check_events to detect if subscriber should be
+	 * woken up immediately ?
+	 */
 
 	if (event_type & SUB_RETRY_RECV)
-		TRACE_DEVEL("subscribe(recv)", QUIC_EV_CONN_XPRTRECV, qc, qcc);
+		TRACE_DEVEL("subscribe(recv)", QUIC_EV_CONN_XPRTRECV, qc);
 
 	if (event_type & SUB_RETRY_SEND)
-		TRACE_DEVEL("subscribe(send)", QUIC_EV_CONN_XPRTSEND, qc, qcc);
+		TRACE_DEVEL("subscribe(send)", QUIC_EV_CONN_XPRTSEND, qc);
 
 	TRACE_LEAVE(QUIC_EV_CONN_SUB, qc);
 
@@ -74,22 +77,24 @@ static int quic_conn_subscribe(struct connection *conn, void *xprt_ctx, int even
  */
 static int quic_conn_unsubscribe(struct connection *conn, void *xprt_ctx, int event_type, struct wait_event *es)
 {
-	int ret;
 	struct quic_conn *qc = conn->handle.qc;
-	struct qcc *qcc = qc->qcc;
 
 	TRACE_ENTER(QUIC_EV_CONN_SUB, qc);
 
 	if (event_type & SUB_RETRY_RECV)
-		TRACE_DEVEL("unsubscribe(recv)", QUIC_EV_CONN_XPRTRECV, qc, qcc);
+		TRACE_DEVEL("unsubscribe(recv)", QUIC_EV_CONN_XPRTRECV, qc);
 	if (event_type & SUB_RETRY_SEND)
-		TRACE_DEVEL("unsubscribe(send)", QUIC_EV_CONN_XPRTSEND, qc, qcc);
+		TRACE_DEVEL("unsubscribe(send)", QUIC_EV_CONN_XPRTSEND, qc);
 
-	ret = conn_unsubscribe(conn, xprt_ctx, event_type, es);
+	es->events &= ~event_type;
+	if (!es->events)
+		qc->subs = NULL;
+
+	/* TODO implement ignore_events similar to conn_unsubscribe() ? */
 
 	TRACE_LEAVE(QUIC_EV_CONN_SUB, qc);
 
-	return ret;
+	return 0;
 }
 
 /* Store in <xprt_ctx> the context attached to <conn>.