add a counter on the struct mq (a queue of mbufs),

and add a block for userspace compiling.

sys/netpfil/ipfw/dn_sched.h

@@ -166,6 +166,7 @@ dn_dequeue(struct dn_queue *q)
 	if (m == NULL)
 		return NULL;
 	q->mq.head = m->m_nextpkt;
+	q->mq.count--;
 
 	/* Update stats for the queue */
 	q->ni.length--;

sys/netpfil/ipfw/ip_dn_io.c

@@ -260,10 +260,39 @@ dn_tag_get(struct mbuf *m)
 static inline void
 mq_append(struct mq *q, struct mbuf *m)
 {
+#ifdef USERSPACE
+	// buffers from netmap need to be copied
+	// XXX note that the routine is not expected to fail
+	ND("append %p to %p", m, q);
+	if (m->m_flags & M_STACK) {
+		struct mbuf *m_new;
+		void *p;
+		int l, ofs;
+
+		ofs = m->m_data - m->__m_extbuf;
+		// XXX allocate
+		MGETHDR(m_new, M_NOWAIT, MT_DATA);
+		ND("*** WARNING, volatile buf %p ext %p %d dofs %d m_new %p",
+			m, m->__m_extbuf, m->__m_extlen, ofs, m_new);
+		p = m_new->__m_extbuf;	/* new pointer */
+		l = m_new->__m_extlen;	/* new len */
+		if (l <= m->__m_extlen) {
+			panic("extlen too large");
+		}
+
+		*m_new = *m;	// copy
+		m_new->m_flags &= ~M_STACK;
+		m_new->__m_extbuf = p; // point to new buffer
+		pkt_copy(m->__m_extbuf, p, m->__m_extlen);
+		m_new->m_data = p + ofs;
+		m = m_new;
+	}
+#endif /* USERSPACE */
 	if (q->head == NULL)
 		q->head = m;
 	else
 		q->tail->m_nextpkt = m;
+	q->count++;
 	q->tail = m;
 	m->m_nextpkt = NULL;
 }
@@ -455,6 +484,7 @@ transmit_event(struct mq *q, struct delay_line *dline, uint64_t now)
 		if (!DN_KEY_LEQ(pkt->output_time, now))
 			break;
 		dline->mq.head = m->m_nextpkt;
+		dline->mq.count--;
 		mq_append(q, m);
 	}
 	if (m != NULL) {

sys/netpfil/ipfw/ip_dn_private.h

@@ -83,6 +83,7 @@ SLIST_HEAD(dn_alg_head, dn_alg);
 
 struct mq {	/* a basic queue of packets*/
         struct mbuf *head, *tail;
+	int count;
 };
 
 static inline void