[NET_SCHED] sch_htb: turn intermediate classes into leaves

- turn intermediate classes into leaves again when their
  last child is deleted (struct htb_class changed)

Signed-off-by: Jarek Poplawski <jarkao2@o2.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 215e68c2b615f1f55edb544a1dbb6a47d99928a6..15f23c5511a869d24927881868bc8a42cf581f5a 100644 (file)
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -147,6 +147,10 @@ struct htb_class {
        psched_tdiff_t mbuffer; /* max wait time */
        long tokens, ctokens;   /* current number of tokens */
        psched_time_t t_c;      /* checkpoint time */
+
+       int prio;               /* For parent to leaf return possible here */
+       int quantum;            /* we do backup. Finally full replacement  */
+                               /* of un.leaf originals should be done. */
 };
 
 /* TODO: maybe compute rate when size is too large .. or drop ? */
@@ -1271,6 +1275,38 @@ static void htb_destroy_filters(struct tcf_proto **fl)
        }
 }
 
+static inline int htb_parent_last_child(struct htb_class *cl)
+{
+       if (!cl->parent)
+               /* the root class */
+               return 0;
+
+       if (!(cl->parent->children.next == &cl->sibling &&
+               cl->parent->children.prev == &cl->sibling))
+               /* not the last child */
+               return 0;
+
+       return 1;
+}
+
+static void htb_parent_to_leaf(struct htb_class *cl, struct Qdisc *new_q)
+{
+       struct htb_class *parent = cl->parent;
+
+       BUG_TRAP(!cl->level && cl->un.leaf.q && !cl->prio_activity);
+
+       parent->level = 0;
+       memset(&parent->un.inner, 0, sizeof(parent->un.inner));
+       INIT_LIST_HEAD(&parent->un.leaf.drop_list);
+       parent->un.leaf.q = new_q ? new_q : &noop_qdisc;
+       parent->un.leaf.quantum = parent->quantum;
+       parent->un.leaf.prio = parent->prio;
+       parent->tokens = parent->buffer;
+       parent->ctokens = parent->cbuffer;
+       PSCHED_GET_TIME(parent->t_c);
+       parent->cmode = HTB_CAN_SEND;
+}
+
 static void htb_destroy_class(struct Qdisc *sch, struct htb_class *cl)
 {
        struct htb_sched *q = qdisc_priv(sch);
@@ -1328,6 +1364,8 @@ 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;
+       struct Qdisc *new_q = NULL;
+       int last_child = 0;
 
        // TODO: why don't allow to delete subtree ? references ? does
        // tc subsys quarantee us that in htb_destroy it holds no class
@@ -1335,6 +1373,12 @@ static int htb_delete(struct Qdisc *sch, unsigned long arg)
        if (!list_empty(&cl->children) || cl->filter_cnt)
                return -EBUSY;
 
+       if (!cl->level && htb_parent_last_child(cl)) {
+               new_q = qdisc_create_dflt(sch->dev, &pfifo_qdisc_ops,
+                                               cl->parent->classid);
+               last_child = 1;
+       }
+
        sch_tree_lock(sch);
 
        /* delete from hash and active; remainder in destroy_class */
@@ -1349,6 +1393,9 @@ static int htb_delete(struct Qdisc *sch, unsigned long arg)
        if (cl->prio_activity)
                htb_deactivate(q, cl);
 
+       if (last_child)
+               htb_parent_to_leaf(cl, new_q);
+
        if (--cl->refcnt == 0)
                htb_destroy_class(sch, cl);
 
@@ -1483,6 +1530,10 @@ static int htb_change_class(struct Qdisc *sch, u32 classid,
                        cl->un.leaf.quantum = hopt->quantum;
                if ((cl->un.leaf.prio = hopt->prio) >= TC_HTB_NUMPRIO)
                        cl->un.leaf.prio = TC_HTB_NUMPRIO - 1;
+
+               /* backup for htb_parent_to_leaf */
+               cl->quantum = cl->un.leaf.quantum;
+               cl->prio = cl->un.leaf.prio;
        }
 
        cl->buffer = hopt->buffer;