[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 <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 17 insertions, 7 deletions

diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 3b36e9d60c20..215e68c2b615 100644
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -1230,11 +1230,7 @@ static int htb_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
                         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 Qdisc *sch, unsigned long arg)
         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, unsigned long arg)
 {
         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, unsigned long arg)
         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 *sch, u32 classid,
                 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, struct qdisc_walker *arg)
 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,