Remove a class from parent's active list when queue is empty

When hfsc_deq_begin can't obtain an mbuf from the queue which can
happen with fq_codel, the hfsc_deq_commit isn't called and HFSC
doesn't get to update the active queue list of the parent class.
To successfully purge and destroy such class, we need to make
sure to run the service curve update routine even if we haven't
dequeued anything so that the parent class doesn't accumulate
stale child classes on its active list.

Reported by Atanas Vladimirov, OK visa

1 files changed, 19 insertions, 13 deletions

diff --git a/sys/net/hfsc.c b/sys/net/hfsc.c
index 00886975b7a..0c02d12e572 100644
--- a/sys/net/hfsc.c
+++ b/sys/net/hfsc.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: hfsc.c,v 1.45 2017/08/17 18:14:39 mikeb Exp $	*/
+/*	$OpenBSD: hfsc.c,v 1.46 2017/08/17 18:22:43 mikeb Exp $	*/
 
 /*
  * Copyright (c) 2012-2013 Henning Brauer <henning@openbsd.org>
@@ -208,6 +208,7 @@ struct hfsc_class	*hfsc_nextclass(struct hfsc_class *);
 void		 hfsc_cl_purge(struct hfsc_if *, struct hfsc_class *,
 		     struct mbuf_list *);
 
+void		 hfsc_update_sc(struct hfsc_if *, struct hfsc_class *, int);
 void		 hfsc_deferred(void *);
 void		 hfsc_update_cfmin(struct hfsc_class *);
 void		 hfsc_set_active(struct hfsc_if *, struct hfsc_class *, int);
@@ -886,8 +887,7 @@ hfsc_deq_begin(struct ifqueue *ifq, void **cookiep)
 	m = hfsc_class_deq_begin(cl, &free_ml);
 	ifq_mfreeml(ifq, &free_ml);
 	if (m == NULL) {
-		/* the class becomes passive */
-		hfsc_set_passive(hif, cl);
+		hfsc_update_sc(hif, cl, 0);
 		return (NULL);
 	}
 
@@ -899,10 +899,18 @@ hfsc_deq_begin(struct ifqueue *ifq, void **cookiep)
 void
 hfsc_deq_commit(struct ifqueue *ifq, struct mbuf *m, void *cookie)
 {
-	struct mbuf_list free_ml = MBUF_LIST_INITIALIZER();
 	struct hfsc_if *hif = ifq->ifq_q;
 	struct hfsc_class *cl = cookie;
-	struct mbuf *m0;
+
+	hfsc_class_deq_commit(cl, m);
+	hfsc_update_sc(hif, cl, m->m_pkthdr.len);
+
+	PKTCNTR_INC(&cl->cl_stats.xmit_cnt, m->m_pkthdr.len);
+}
+
+void
+hfsc_update_sc(struct hfsc_if *hif, struct hfsc_class *cl, int len)
+{
 	int next_len, realtime = 0;
 	u_int64_t cur_time = hif->hif_microtime;
 
@@ -910,13 +918,9 @@ hfsc_deq_commit(struct ifqueue *ifq, struct mbuf *m, void *cookie)
 	if (cl->cl_rsc != NULL)
 		realtime = (cl->cl_e <= cur_time);
 
-	hfsc_class_deq_commit(cl, m);
-
-	PKTCNTR_INC(&cl->cl_stats.xmit_cnt, m->m_pkthdr.len);
-
-	hfsc_update_vf(cl, m->m_pkthdr.len, cur_time);
+	hfsc_update_vf(cl, len, cur_time);
 	if (realtime)
-		cl->cl_cumul += m->m_pkthdr.len;
+		cl->cl_cumul += len;
 
 	if (hfsc_class_qlength(cl) > 0) {
 		/*
@@ -925,9 +929,11 @@ hfsc_deq_commit(struct ifqueue *ifq, struct mbuf *m, void *cookie)
 		 * be used with an external queue manager.
 		 */
 		if (cl->cl_rsc != NULL) {
+			struct mbuf *m0;
+
 			/* update ed */
-			m0 = hfsc_class_deq_begin(cl, &free_ml);
-			ifq_mfreeml(ifq, &free_ml);
+			KASSERT(cl->cl_qops == pfq_hfsc_ops);
+			m0 = MBUF_LIST_FIRST(&cl->cl_q.q);
 			next_len = m0->m_pkthdr.len;
 
 			if (realtime)