[PKT_SCHED]: Convert sch_red to a classful qdisc

Convert sch_red to a classful qdisc. All qdiscs that maintain accurate
backlog counters are eligible as child qdiscs. When a queue limit larger
than zero is given, a bfifo qdisc is used for backwards compatibility.
Current versions of tc enforce a limit larger than zero, other users
can avoid creating the default qdisc by using zero.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Acked-by: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 163 insertions, 16 deletions

diff --git a/net/sched/sch_red.c b/net/sched/sch_red.c
index dccfa44c2d71..2be563cba72b 100644
--- a/net/sched/sch_red.c
+++ b/net/sched/sch_red.c
@@ -44,6 +44,7 @@ struct red_sched_data
         unsigned char           flags;
         struct red_parms        parms;
         struct red_stats        stats;
+        struct Qdisc            *qdisc;
 };
 
 static inline int red_use_ecn(struct red_sched_data *q)
@@ -59,8 +60,10 @@ static inline int red_use_harddrop(struct red_sched_data *q)
 static int red_enqueue(struct sk_buff *skb, struct Qdisc* sch)
 {
         struct red_sched_data *q = qdisc_priv(sch);
+        struct Qdisc *child = q->qdisc;
+        int ret;
 
-        q->parms.qavg = red_calc_qavg(&q->parms, sch->qstats.backlog);
+        q->parms.qavg = red_calc_qavg(&q->parms, child->qstats.backlog);
 
         if (red_is_idling(&q->parms))
                 red_end_of_idle_period(&q->parms);
@@ -91,11 +94,16 @@ static int red_enqueue(struct sk_buff *skb, struct Qdisc* sch)
                         break;
         }
 
-        if (sch->qstats.backlog + skb->len <= q->limit)
-                return qdisc_enqueue_tail(skb, sch);
-
-        q->stats.pdrop++;
-        return qdisc_drop(skb, sch);
+        ret = child->enqueue(skb, child);
+        if (likely(ret == NET_XMIT_SUCCESS)) {
+                sch->bstats.bytes += skb->len;
+                sch->bstats.packets++;
+                sch->q.qlen++;
+        } else {
+                q->stats.pdrop++;
+                sch->qstats.drops++;
+        }
+        return ret;
 
 congestion_drop:
         qdisc_drop(skb, sch);
@@ -105,21 +113,30 @@ congestion_drop:
 static int red_requeue(struct sk_buff *skb, struct Qdisc* sch)
 {
         struct red_sched_data *q = qdisc_priv(sch);
+        struct Qdisc *child = q->qdisc;
+        int ret;
 
         if (red_is_idling(&q->parms))
                 red_end_of_idle_period(&q->parms);
 
-        return qdisc_requeue(skb, sch);
+        ret = child->ops->requeue(skb, child);
+        if (likely(ret == NET_XMIT_SUCCESS)) {
+                sch->qstats.requeues++;
+                sch->q.qlen++;
+        }
+        return ret;
 }
 
 static struct sk_buff * red_dequeue(struct Qdisc* sch)
 {
         struct sk_buff *skb;
         struct red_sched_data *q = qdisc_priv(sch);
+        struct Qdisc *child = q->qdisc;
 
-        skb = qdisc_dequeue_head(sch);
-
-        if (skb == NULL && !red_is_idling(&q->parms))
+        skb = child->dequeue(child);
+        if (skb)
+                sch->q.qlen--;
+        else if (!red_is_idling(&q->parms))
                 red_start_of_idle_period(&q->parms);
 
         return skb;
@@ -127,14 +144,14 @@ static struct sk_buff * red_dequeue(struct Qdisc* sch)
 
 static unsigned int red_drop(struct Qdisc* sch)
 {
-        struct sk_buff *skb;
         struct red_sched_data *q = qdisc_priv(sch);
+        struct Qdisc *child = q->qdisc;
+        unsigned int len;
 
-        skb = qdisc_dequeue_tail(sch);
-        if (skb) {
-                unsigned int len = skb->len;
+        if (child->ops->drop && (len = child->ops->drop(child)) > 0) {
                 q->stats.other++;
-                qdisc_drop(skb, sch);
+                sch->qstats.drops++;
+                sch->q.qlen--;
                 return len;
         }
 
@@ -148,15 +165,48 @@ static void red_reset(struct Qdisc* sch)
 {
         struct red_sched_data *q = qdisc_priv(sch);
 
-        qdisc_reset_queue(sch);
+        qdisc_reset(q->qdisc);
+        sch->q.qlen = 0;
         red_restart(&q->parms);
 }
 
+static void red_destroy(struct Qdisc *sch)
+{
+        struct red_sched_data *q = qdisc_priv(sch);
+        qdisc_destroy(q->qdisc);
+}
+
+static struct Qdisc *red_create_dflt(struct net_device *dev, u32 limit)
+{
+        struct Qdisc *q = qdisc_create_dflt(dev, &bfifo_qdisc_ops);
+        struct rtattr *rta;
+        int ret;
+
+        if (q) {
+                rta = kmalloc(RTA_LENGTH(sizeof(struct tc_fifo_qopt)),
+                              GFP_KERNEL);
+                if (rta) {
+                        rta->rta_type = RTM_NEWQDISC;
+                        rta->rta_len = RTA_LENGTH(sizeof(struct tc_fifo_qopt));
+                        ((struct tc_fifo_qopt *)RTA_DATA(rta))->limit = limit;
+
+                        ret = q->ops->change(q, rta);
+                        kfree(rta);
+
+                        if (ret == 0)
+                                return q;
+                }
+                qdisc_destroy(q);
+        }
+        return NULL;
+}
+
 static int red_change(struct Qdisc *sch, struct rtattr *opt)
 {
         struct red_sched_data *q = qdisc_priv(sch);
         struct rtattr *tb[TCA_RED_MAX];
         struct tc_red_qopt *ctl;
+        struct Qdisc *child = NULL;
 
         if (opt == NULL || rtattr_parse_nested(tb, TCA_RED_MAX, opt))
                 return -EINVAL;
@@ -169,9 +219,17 @@ static int red_change(struct Qdisc *sch, struct rtattr *opt)
 
         ctl = RTA_DATA(tb[TCA_RED_PARMS-1]);
 
+        if (ctl->limit > 0) {
+                child = red_create_dflt(sch->dev, ctl->limit);
+                if (child == NULL)
+                        return -ENOMEM;
+        }
+
         sch_tree_lock(sch);
         q->flags = ctl->flags;
         q->limit = ctl->limit;
+        if (child)
+                qdisc_destroy(xchg(&q->qdisc, child));
 
         red_set_parms(&q->parms, ctl->qth_min, ctl->qth_max, ctl->Wlog,
                                  ctl->Plog, ctl->Scell_log,
@@ -186,6 +244,9 @@ static int red_change(struct Qdisc *sch, struct rtattr *opt)
 
 static int red_init(struct Qdisc* sch, struct rtattr *opt)
 {
+        struct red_sched_data *q = qdisc_priv(sch);
+
+        q->qdisc = &noop_qdisc;
         return red_change(sch, opt);
 }
 
@@ -224,15 +285,101 @@ static int red_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
         return gnet_stats_copy_app(d, &st, sizeof(st));
 }
 
+static int red_dump_class(struct Qdisc *sch, unsigned long cl,
+                          struct sk_buff *skb, struct tcmsg *tcm)
+{
+        struct red_sched_data *q = qdisc_priv(sch);
+
+        if (cl != 1)
+                return -ENOENT;
+        tcm->tcm_handle |= TC_H_MIN(1);
+        tcm->tcm_info = q->qdisc->handle;
+        return 0;
+}
+
+static int red_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
+                     struct Qdisc **old)
+{
+        struct red_sched_data *q = qdisc_priv(sch);
+
+        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 *red_leaf(struct Qdisc *sch, unsigned long arg)
+{
+        struct red_sched_data *q = qdisc_priv(sch);
+        return q->qdisc;
+}
+
+static unsigned long red_get(struct Qdisc *sch, u32 classid)
+{
+        return 1;
+}
+
+static void red_put(struct Qdisc *sch, unsigned long arg)
+{
+        return;
+}
+
+static int red_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
+                            struct rtattr **tca, unsigned long *arg)
+{
+        return -ENOSYS;
+}
+
+static int red_delete(struct Qdisc *sch, unsigned long cl)
+{
+        return -ENOSYS;
+}
+
+static void red_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 **red_find_tcf(struct Qdisc *sch, unsigned long cl)
+{
+        return NULL;
+}
+
+static struct Qdisc_class_ops red_class_ops = {
+        .graft          =       red_graft,
+        .leaf           =       red_leaf,
+        .get            =       red_get,
+        .put            =       red_put,
+        .change         =       red_change_class,
+        .delete         =       red_delete,
+        .walk           =       red_walk,
+        .tcf_chain      =       red_find_tcf,
+        .dump           =       red_dump_class,
+};
+
 static struct Qdisc_ops red_qdisc_ops = {
         .id             =       "red",
         .priv_size      =       sizeof(struct red_sched_data),
+        .cl_ops         =       &red_class_ops,
         .enqueue        =       red_enqueue,
         .dequeue        =       red_dequeue,
         .requeue        =       red_requeue,
         .drop           =       red_drop,
         .init           =       red_init,
         .reset          =       red_reset,
+        .destroy        =       red_destroy,
         .change         =       red_change,
         .dump           =       red_dump,
         .dump_stats     =       red_dump_stats,