Don't attempt to deactivate a class that doesn't have any packets in it

Classes are considered "active" when they have packets assigned to them.
Active classes are tracked on various lists and during the purge operation
must be dissociated from them.  During factoring out of the HFSC internal
FIFO operations, the check for whether the class is empty got lost.

Issue reported and fix tested by abieber@ and myself.

1 files changed, 9 insertions, 2 deletions

diff --git a/sys/net/hfsc.c b/sys/net/hfsc.c
index 6f9c9edf4ff..410bea733c6 100644
--- a/sys/net/hfsc.c
+++ b/sys/net/hfsc.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: hfsc.c,v 1.43 2017/07/19 13:41:20 mikeb Exp $	*/
+/*	$OpenBSD: hfsc.c,v 1.44 2017/07/24 15:20:46 mikeb Exp $	*/
 
 /*
  * Copyright (c) 2012-2013 Henning Brauer <henning@openbsd.org>
@@ -961,7 +961,14 @@ hfsc_deferred(void *arg)
 void
 hfsc_cl_purge(struct hfsc_if *hif, struct hfsc_class *cl, struct mbuf_list *ml)
 {
-	hfsc_class_purge(cl, ml);
+	struct mbuf_list ml2 = MBUF_LIST_INITIALIZER();
+
+	hfsc_class_purge(cl, &ml2);
+	if (ml_empty(&ml2))
+		return;
+
+	ml_enlist(ml, &ml2);
+
 	hfsc_update_vf(cl, 0, 0);	/* remove cl from the actlist */
 	hfsc_set_passive(hif, cl);
 }