cbs: Add support for the graft function

This will allow to install a child qdisc under cbs. The main use case
is to install ETF (Earliest TxTime First) qdisc under cbs, so there's
another level of control for time-sensitive traffic.

Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sched/sch_cbs.c b/net/sched/sch_cbs.c
index cdd96b9a27bcf1ef510e282ff97a8710132b1ce6..e26a24017faa6b15d1f6100350d9c39b539ce50b 100644 (file)
--- a/net/sched/sch_cbs.c
+++ b/net/sched/sch_cbs.c
@@ -78,18 +78,42 @@ struct cbs_sched_data {
        s64 sendslope; /* in bytes/s */
        s64 idleslope; /* in bytes/s */
        struct qdisc_watchdog watchdog;
-       int (*enqueue)(struct sk_buff *skb, struct Qdisc *sch);
+       int (*enqueue)(struct sk_buff *skb, struct Qdisc *sch,
+                      struct sk_buff **to_free);
        struct sk_buff *(*dequeue)(struct Qdisc *sch);
+       struct Qdisc *qdisc;
 };
 
-static int cbs_enqueue_offload(struct sk_buff *skb, struct Qdisc *sch)
+static int cbs_child_enqueue(struct sk_buff *skb, struct Qdisc *sch,
+                            struct Qdisc *child,
+                            struct sk_buff **to_free)
 {
-       return qdisc_enqueue_tail(skb, sch);
+       int err;
+
+       err = child->ops->enqueue(skb, child, to_free);
+       if (err != NET_XMIT_SUCCESS)
+               return err;
+
+       qdisc_qstats_backlog_inc(sch, skb);
+       sch->q.qlen++;
+
+       return NET_XMIT_SUCCESS;
 }
 
-static int cbs_enqueue_soft(struct sk_buff *skb, struct Qdisc *sch)
+static int cbs_enqueue_offload(struct sk_buff *skb, struct Qdisc *sch,
+                              struct sk_buff **to_free)
 {
        struct cbs_sched_data *q = qdisc_priv(sch);
+       struct Qdisc *qdisc = q->qdisc;
+
+       return cbs_child_enqueue(skb, sch, qdisc, to_free);
+}
+
+static int cbs_enqueue_soft(struct sk_buff *skb, struct Qdisc *sch,
+                           struct sk_buff **to_free)
+{
+       struct cbs_sched_data *q = qdisc_priv(sch);
+       struct Qdisc *qdisc = q->qdisc;
 
        if (sch->q.qlen == 0 && q->credits > 0) {
                /* We need to stop accumulating credits when there's
@@ -99,7 +123,7 @@ static int cbs_enqueue_soft(struct sk_buff *skb, struct Qdisc *sch)
                q->last = ktime_get_ns();
        }
 
-       return qdisc_enqueue_tail(skb, sch);
+       return cbs_child_enqueue(skb, sch, qdisc, to_free);
 }
 
 static int cbs_enqueue(struct sk_buff *skb, struct Qdisc *sch,
@@ -107,7 +131,7 @@ static int cbs_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 {
        struct cbs_sched_data *q = qdisc_priv(sch);
 
-       return q->enqueue(skb, sch);
+       return q->enqueue(skb, sch, to_free);
 }
 
 /* timediff is in ns, slope is in bytes/s */
@@ -132,9 +156,25 @@ static s64 credits_from_len(unsigned int len, s64 slope, s64 port_rate)
        return div64_s64(len * slope, port_rate);
 }
 
+static struct sk_buff *cbs_child_dequeue(struct Qdisc *sch, struct Qdisc *child)
+{
+       struct sk_buff *skb;
+
+       skb = child->ops->dequeue(child);
+       if (!skb)
+               return NULL;
+
+       qdisc_qstats_backlog_dec(sch, skb);
+       qdisc_bstats_update(sch, skb);
+       sch->q.qlen--;
+
+       return skb;
+}
+
 static struct sk_buff *cbs_dequeue_soft(struct Qdisc *sch)
 {
        struct cbs_sched_data *q = qdisc_priv(sch);
+       struct Qdisc *qdisc = q->qdisc;
        s64 now = ktime_get_ns();
        struct sk_buff *skb;
        s64 credits;
@@ -157,8 +197,7 @@ static struct sk_buff *cbs_dequeue_soft(struct Qdisc *sch)
                        return NULL;
                }
        }
-
-       skb = qdisc_dequeue_head(sch);
+       skb = cbs_child_dequeue(sch, qdisc);
        if (!skb)
                return NULL;
 
@@ -178,7 +217,10 @@ static struct sk_buff *cbs_dequeue_soft(struct Qdisc *sch)
 
 static struct sk_buff *cbs_dequeue_offload(struct Qdisc *sch)
 {
-       return qdisc_dequeue_head(sch);
+       struct cbs_sched_data *q = qdisc_priv(sch);
+       struct Qdisc *qdisc = q->qdisc;
+
+       return cbs_child_dequeue(sch, qdisc);
 }
 
 static struct sk_buff *cbs_dequeue(struct Qdisc *sch)
@@ -310,6 +352,13 @@ static int cbs_init(struct Qdisc *sch, struct nlattr *opt,
                return -EINVAL;
        }
 
+       q->qdisc = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
+                                    sch->handle, extack);
+       if (!q->qdisc)
+               return -ENOMEM;
+
+       qdisc_hash_add(q->qdisc, false);
+
        q->queue = sch->dev_queue - netdev_get_tx_queue(dev, 0);
 
        q->enqueue = cbs_enqueue_soft;
@@ -328,6 +377,9 @@ static void cbs_destroy(struct Qdisc *sch)
        qdisc_watchdog_cancel(&q->watchdog);
 
        cbs_disable_offload(dev, q);
+
+       if (q->qdisc)
+               qdisc_destroy(q->qdisc);
 }
 
 static int cbs_dump(struct Qdisc *sch, struct sk_buff *skb)
@@ -356,8 +408,72 @@ static int cbs_dump(struct Qdisc *sch, struct sk_buff *skb)
        return -1;
 }
 
+static int cbs_dump_class(struct Qdisc *sch, unsigned long cl,
+                         struct sk_buff *skb, struct tcmsg *tcm)
+{
+       struct cbs_sched_data *q = qdisc_priv(sch);
+
+       if (cl != 1 || !q->qdisc)       /* only one class */
+               return -ENOENT;
+
+       tcm->tcm_handle |= TC_H_MIN(1);
+       tcm->tcm_info = q->qdisc->handle;
+
+       return 0;
+}
+
+static int cbs_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
+                    struct Qdisc **old, struct netlink_ext_ack *extack)
+{
+       struct cbs_sched_data *q = qdisc_priv(sch);
+
+       if (!new) {
+               new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
+                                       sch->handle, NULL);
+               if (!new)
+                       new = &noop_qdisc;
+       }
+
+       *old = qdisc_replace(sch, new, &q->qdisc);
+       return 0;
+}
+
+static struct Qdisc *cbs_leaf(struct Qdisc *sch, unsigned long arg)
+{
+       struct cbs_sched_data *q = qdisc_priv(sch);
+
+       return q->qdisc;
+}
+
+static unsigned long cbs_find(struct Qdisc *sch, u32 classid)
+{
+       return 1;
+}
+
+static void cbs_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 const struct Qdisc_class_ops cbs_class_ops = {
+       .graft          =       cbs_graft,
+       .leaf           =       cbs_leaf,
+       .find           =       cbs_find,
+       .walk           =       cbs_walk,
+       .dump           =       cbs_dump_class,
+};
+
 static struct Qdisc_ops cbs_qdisc_ops __read_mostly = {
        .id             =       "cbs",
+       .cl_ops         =       &cbs_class_ops,
        .priv_size      =       sizeof(struct cbs_sched_data),
        .enqueue        =       cbs_enqueue,
        .dequeue        =       cbs_dequeue,