[NET_SCHED]: Fix endless loops (part 3): HFSC

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

All queue purging goes through hfsc_purge_queue(), which is used in
three cases: grafting, class creation (when a leaf class is turned
into an intermediate class by attaching a new class) and class
deletion. In all cases qdisc_tree_decrease_len() is needed.

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

1 files changed, 13 insertions, 5 deletions

diff --git a/net/sched/sch_hfsc.c b/net/sched/sch_hfsc.c
index 1142d298ecf6..2d437447e085 100644
--- a/net/sched/sch_hfsc.c
+++ b/net/sched/sch_hfsc.c
@@ -957,11 +957,7 @@ hfsc_purge_queue(struct Qdisc *sch, struct hfsc_class *cl)
         unsigned int len = cl->qdisc->q.qlen;
 
         qdisc_reset(cl->qdisc);
-        if (len > 0) {
-                update_vf(cl, 0, 0);
-                set_passive(cl);
-                sch->q.qlen -= len;
-        }
+        qdisc_tree_decrease_qlen(cl->qdisc, len);
 }
 
 static void
@@ -1295,6 +1291,17 @@ hfsc_class_leaf(struct Qdisc *sch, unsigned long arg)
         return NULL;
 }
 
+static void
+hfsc_qlen_notify(struct Qdisc *sch, unsigned long arg)
+{
+        struct hfsc_class *cl = (struct hfsc_class *)arg;
+
+        if (cl->qdisc->q.qlen == 0) {
+                update_vf(cl, 0, 0);
+                set_passive(cl);
+        }
+}
+
 static unsigned long
 hfsc_get_class(struct Qdisc *sch, u32 classid)
 {
@@ -1779,6 +1786,7 @@ static struct Qdisc_class_ops hfsc_class_ops = {
         .delete         = hfsc_delete_class,
         .graft          = hfsc_graft_class,
         .leaf           = hfsc_class_leaf,
+        .qlen_notify    = hfsc_qlen_notify,
         .get            = hfsc_get_class,
         .put            = hfsc_put_class,
         .bind_tcf       = hfsc_bind_tcf,