[PATCH] netem packet scheduler class support

[Stephen Hemminger <shemminger@xxxxxxxx>]

Simple enhancement to netem packet scheduler that makes it classful so
that the underlying pfifo default discipline can be substituted with something
else (tbf, red, ...)

Signed-off-by: Stephen Hemminger <shemminger@xxxxxxxx>

--- linux-2.6/net/sched/sch_netem.c     2004-07-12 08:05:35.439533776 -0700
+++ tcp-2.6/net/sched/sch_netem.c       2004-07-12 09:00:23.251710352 -0700
@@ -829,8 +829,95 @@ rtattr_failure:
        return -1;
 }
 
+static int netem_dump_class(struct Qdisc *sch, unsigned long cl,
+                         struct sk_buff *skb, struct tcmsg *tcm)
+{
+       struct netem_sched_data *q = (struct netem_sched_data*)sch->data;
+
+       if (cl != 1)    /* only one class */
+               return -ENOENT;
+
+       tcm->tcm_handle |= TC_H_MIN(1);
+       tcm->tcm_info = q->qdisc->handle;
+
+       return 0;
+}
+
+static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
+                    struct Qdisc **old)
+{
+       struct netem_sched_data *q = (struct netem_sched_data *)sch->data;
+
+       if (new == NULL)
+               new = &noop_qdisc;
+
+       sch_tree_lock(sch);
+       *old = xchg(&q->qdisc, new);
+       qdisc_reset(*old);
+       sch->q.qlen = 0;
+       sch_tree_unlock(sch);
+
+       return 0;
+}
+
+static struct Qdisc *netem_leaf(struct Qdisc *sch, unsigned long arg)
+{
+       struct netem_sched_data *q = (struct netem_sched_data *)sch->data;
+       return q->qdisc;
+}
+
+static unsigned long netem_get(struct Qdisc *sch, u32 classid)
+{
+       return 1;
+}
+
+static void netem_put(struct Qdisc *sch, unsigned long arg)
+{
+}
+
+static int netem_change_class(struct Qdisc *sch, u32 classid, u32 parentid, 
+                           struct rtattr **tca, unsigned long *arg)
+{
+       return -ENOSYS;
+}
+
+static int netem_delete(struct Qdisc *sch, unsigned long arg)
+{
+       return -ENOSYS;
+}
+
+static void netem_walk(struct Qdisc *sch, struct qdisc_walker *walker)
+{
+       if (!walker->stop) {
+               if (walker->count >= walker->skip)
+                       if (walker->fn(sch, 1, walker) < 0) {
+                               walker->stop = 1;
+                               return;
+                       }
+               walker->count++;
+       }
+}
+
+static struct tcf_proto **netem_find_tcf(struct Qdisc *sch, unsigned long cl)
+{
+       return NULL;
+}
+
+static struct Qdisc_class_ops netem_class_ops = {
+       .graft          =       netem_graft,
+       .leaf           =       netem_leaf,
+       .get            =       netem_get,
+       .put            =       netem_put,
+       .change         =       netem_change_class,
+       .delete         =       netem_delete,
+       .walk           =       netem_walk,
+       .tcf_chain      =       netem_find_tcf,
+       .dump           =       netem_dump_class,
+};
+
 static struct Qdisc_ops netem_qdisc_ops = {
        .id             =       "netem",
+       .cl_ops         =       &netem_class_ops,
        .priv_size      =       sizeof(struct netem_sched_data),
        .enqueue        =       netem_enqueue,
        .dequeue        =       netem_dequeue,