Subject: Re: [NET_SCHED 06/06]: Fix endless loops (part 4): HTB

From: Martin Devera <[email-masked]>
Date: Mon, 20 Nov 2006 14:39:42 +0100

Patrick McHardy wrote:

 > Martin, can you please review the HTB parts?

it seems all right to me :-) Good work!

--------- snip ---------

[NET_SCHED]: Fix endless loops (part 4): HTB

Convert HTB to use qdisc_tree_decrease_len() and add a callback
for deactivating a class when its child queue becomes empty.

Signed-off-by: Patrick McHardy <[email-masked]>
Acked-by: Martin Devera <[email-masked]>

---
commit cc6f4de81d666f76192bee629473ff6fbd66286c
tree 237aa915ea3b619fb817e719821bb0667e19eafd
parent 62ab4431af7bccd0a8cd9b1933fb03e78fd63252
author Patrick McHardy <[email-masked]> Mon, 20 Nov 2006 13:50:11 +0100
committer Patrick McHardy <[email-masked]> Mon, 20 Nov 2006 13:50:11 +0100

  net/sched/sch_htb.c |   24 +++++++++++++++++-------
  1 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 3b36e9d..215e68c 100644
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -1230,11 +1230,7 @@ static int htb_graft(struct Qdisc *sch,
  			return -ENOBUFS;
  		sch_tree_lock(sch);
  		if ((*old = xchg(&cl->un.leaf.q, new)) != NULL) {
-			if (cl->prio_activity)
-				htb_deactivate(qdisc_priv(sch), cl);
-
-			/* TODO: is it correct ? Why CBQ doesn't do it ? */
-			sch->q.qlen -= (*old)->q.qlen;
+			qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
  			qdisc_reset(*old);
  		}
  		sch_tree_unlock(sch);
@@ -1249,6 +1245,14 @@ static struct Qdisc *htb_leaf(struct Qdi
  	return (cl && !cl->level) ? cl->un.leaf.q : NULL;
  }

+static void htb_qlen_notify(struct Qdisc *sch, unsigned long arg)
+{
+	struct htb_class *cl = (struct htb_class *)arg;
+
+	if (cl->un.leaf.q->q.qlen == 0)
+		htb_deactivate(qdisc_priv(sch), cl);
+}
+
  static unsigned long htb_get(struct Qdisc *sch, u32 classid)
  {
  	struct htb_class *cl = htb_find(classid, sch);
@@ -1323,6 +1327,7 @@ static int htb_delete(struct Qdisc *sch,
  {
  	struct htb_sched *q = qdisc_priv(sch);
  	struct htb_class *cl = (struct htb_class *)arg;
+	unsigned int qlen;

  	// TODO: why don't allow to delete subtree ? references ? does
  	// tc subsys quarantee us that in htb_destroy it holds no class
@@ -1336,8 +1341,9 @@ static int htb_delete(struct Qdisc *sch,
  	hlist_del_init(&cl->hlist);

  	if (!cl->level) {
-		sch->q.qlen -= cl->un.leaf.q->q.qlen;
+		qlen = cl->un.leaf.q->q.qlen;
  		qdisc_reset(cl->un.leaf.q);
+		qdisc_tree_decrease_qlen(cl->un.leaf.q, qlen);
  	}

  	if (cl->prio_activity)
@@ -1419,8 +1425,11 @@ static int htb_change_class(struct Qdisc
  		new_q = qdisc_create_dflt(sch->dev, &pfifo_qdisc_ops, classid);
  		sch_tree_lock(sch);
  		if (parent && !parent->level) {
+			unsigned int qlen = parent->un.leaf.q->q.qlen;
+
  			/* turn parent into inner node */
-			sch->q.qlen -= parent->un.leaf.q->q.qlen;
+			qdisc_reset(parent->un.leaf.q);
+			qdisc_tree_decrease_qlen(parent->un.leaf.q, qlen);
  			qdisc_destroy(parent->un.leaf.q);
  			if (parent->prio_activity)
  				htb_deactivate(q, parent);
@@ -1568,6 +1577,7 @@ static void htb_walk(struct Qdisc *sch,
  static struct Qdisc_class_ops htb_class_ops = {
  	.graft		=	htb_graft,
  	.leaf		=	htb_leaf,
+	.qlen_notify	=	htb_qlen_notify,
  	.get		=	htb_get,
  	.put		=	htb_put,
  	.change		=	htb_change_class,