/*
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* SPDX-License-Identifier: GPL-2.0
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*
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* Copyright (C) 2020 Philippe Gerum <rpm@xenomai.org>
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*/
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#include <linux/netdevice.h>
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#include <linux/skbuff.h>
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#include <net/pkt_sched.h>
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#include <net/pkt_cls.h>
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/*
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* With Qdisc[2], 0=oob_fallback and 1=inband. User can graft whatever
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* qdisc on these slots; both preset to pfifo_ops. skb->oob is checked
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* to determine which qdisc should handle the packet eventually.
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*/
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struct oob_qdisc_priv {
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struct Qdisc *qdisc[2]; /* 0=oob_fallback, 1=in-band */
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struct tcf_proto __rcu *filter_list;
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struct tcf_block *block;
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};
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static int oob_enqueue(struct sk_buff *skb, struct Qdisc *sch,
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struct sk_buff **to_free)
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{
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struct oob_qdisc_priv *p = qdisc_priv(sch);
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struct net_device *dev = skb->dev;
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struct Qdisc *qdisc;
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int ret;
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/*
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* If the device accepts oob traffic and can handle it
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* directly from the oob stage, pass the outgoing packet to
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* the transmit handler of the oob stack. This makes sure that
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* all traffic, including the in-band one, flows through the
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* oob stack which may implement its own queuing discipline.
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*
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* netif_xmit_oob() might fail handling the packet, in which
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* case we leave it to the in-band packet scheduler, applying
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* a best-effort strategy by giving higher priority to oob
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* packets over mere in-band traffic.
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*/
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if (dev && netif_oob_diversion(dev) && netdev_is_oob_capable(dev)) {
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ret = netif_xmit_oob(skb);
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if (ret == NET_XMIT_SUCCESS)
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return NET_XMIT_SUCCESS;
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}
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/*
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* Out-of-band fast lane is closed. Best effort: use a special
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* 'high priority' queue for oob packets we handle from
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* in-band context the usual way through the common stack.
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*/
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qdisc = skb->oob ? p->qdisc[0] : p->qdisc[1];
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ret = qdisc_enqueue(skb, qdisc, to_free);
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if (ret == NET_XMIT_SUCCESS) {
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sch->q.qlen++;
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return NET_XMIT_SUCCESS;
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}
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if (net_xmit_drop_count(ret))
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qdisc_qstats_drop(sch);
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return ret;
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}
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static struct sk_buff *oob_dequeue(struct Qdisc *sch)
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{
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struct oob_qdisc_priv *p = qdisc_priv(sch);
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struct sk_buff *skb;
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struct Qdisc *qdisc;
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int band;
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/*
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* First try to dequeue pending out-of-band packets. If none,
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* then check for in-band traffic.
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*/
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for (band = 0; band < 2; band++) {
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qdisc = p->qdisc[band];
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skb = qdisc->dequeue(qdisc);
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if (skb) {
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qdisc_bstats_update(sch, skb);
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sch->q.qlen--;
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return skb;
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}
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}
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return NULL;
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}
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static struct sk_buff *oob_peek(struct Qdisc *sch)
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{
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struct oob_qdisc_priv *p = qdisc_priv(sch);
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struct sk_buff *skb;
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struct Qdisc *qdisc;
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int band;
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for (band = 0; band < 2; band++) {
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qdisc = p->qdisc[band];
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skb = qdisc->ops->peek(qdisc);
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if (skb)
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return skb;
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}
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return NULL;
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}
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static int oob_init(struct Qdisc *sch, struct nlattr *opt,
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struct netlink_ext_ack *extack)
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{
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struct oob_qdisc_priv *p = qdisc_priv(sch);
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int ret;
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ret = tcf_block_get(&p->block, &p->filter_list, sch, extack);
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if (ret)
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return ret;
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p->qdisc[0] = qdisc_create_dflt(sch->dev_queue,
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&pfifo_qdisc_ops, sch->handle,
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extack);
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p->qdisc[1] = qdisc_create_dflt(sch->dev_queue,
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&pfifo_fast_ops, sch->handle,
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extack);
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return 0;
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}
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static void oob_reset(struct Qdisc *sch)
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{
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struct oob_qdisc_priv *p = qdisc_priv(sch);
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qdisc_reset(p->qdisc[0]);
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qdisc_reset(p->qdisc[1]);
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sch->q.qlen = 0;
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}
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static void oob_destroy(struct Qdisc *sch)
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{
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struct oob_qdisc_priv *p = qdisc_priv(sch);
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tcf_block_put(p->block);
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qdisc_put(p->qdisc[0]);
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qdisc_put(p->qdisc[1]);
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}
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static int oob_tune(struct Qdisc *sch, struct nlattr *opt,
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struct netlink_ext_ack *extack)
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{
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return 0;
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}
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static int oob_dump(struct Qdisc *sch, struct sk_buff *skb)
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{
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return skb->len;
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}
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static int oob_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
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struct Qdisc **old, struct netlink_ext_ack *extack)
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{
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struct oob_qdisc_priv *p = qdisc_priv(sch);
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unsigned long band = arg - 1;
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if (new == NULL)
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new = &noop_qdisc;
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*old = qdisc_replace(sch, new, &p->qdisc[band]);
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return 0;
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}
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static struct Qdisc *
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oob_leaf(struct Qdisc *sch, unsigned long arg)
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{
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struct oob_qdisc_priv *p = qdisc_priv(sch);
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unsigned long band = arg - 1;
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return p->qdisc[band];
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}
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static unsigned long oob_find(struct Qdisc *sch, u32 classid)
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{
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unsigned long band = TC_H_MIN(classid);
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return band - 1 >= 2 ? 0 : band;
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}
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static int oob_dump_class(struct Qdisc *sch, unsigned long cl,
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struct sk_buff *skb, struct tcmsg *tcm)
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{
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struct oob_qdisc_priv *p = qdisc_priv(sch);
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tcm->tcm_handle |= TC_H_MIN(cl);
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tcm->tcm_info = p->qdisc[cl - 1]->handle;
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return 0;
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}
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static int oob_dump_class_stats(struct Qdisc *sch, unsigned long cl,
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struct gnet_dump *d)
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{
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struct oob_qdisc_priv *p = qdisc_priv(sch);
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struct Qdisc *cl_q = p->qdisc[cl - 1];
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if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch),
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d, cl_q->cpu_bstats, &cl_q->bstats) < 0 ||
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qdisc_qstats_copy(d, cl_q) < 0)
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return -1;
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return 0;
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}
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static void oob_walk(struct Qdisc *sch, struct qdisc_walker *arg)
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{
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int band;
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if (arg->stop)
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return;
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for (band = 0; band < 2; band++) {
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if (arg->count < arg->skip) {
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arg->count++;
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continue;
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}
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if (arg->fn(sch, band + 1, arg) < 0) {
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arg->stop = 1;
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break;
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}
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arg->count++;
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}
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}
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static unsigned long oob_tcf_bind(struct Qdisc *sch, unsigned long parent,
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u32 classid)
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{
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return oob_find(sch, classid);
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}
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static void oob_tcf_unbind(struct Qdisc *q, unsigned long cl)
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{
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}
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static struct tcf_block *oob_tcf_block(struct Qdisc *sch, unsigned long cl,
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struct netlink_ext_ack *extack)
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{
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struct oob_qdisc_priv *p = qdisc_priv(sch);
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if (cl)
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return NULL;
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return p->block;
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}
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static const struct Qdisc_class_ops oob_class_ops = {
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.graft = oob_graft,
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.leaf = oob_leaf,
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.find = oob_find,
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.walk = oob_walk,
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.dump = oob_dump_class,
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.dump_stats = oob_dump_class_stats,
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.tcf_block = oob_tcf_block,
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.bind_tcf = oob_tcf_bind,
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.unbind_tcf = oob_tcf_unbind,
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};
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static struct Qdisc_ops oob_qdisc_ops __read_mostly = {
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.cl_ops = &oob_class_ops,
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.id = "oob",
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.priv_size = sizeof(struct oob_qdisc_priv),
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.enqueue = oob_enqueue,
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.dequeue = oob_dequeue,
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.peek = oob_peek,
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.init = oob_init,
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.reset = oob_reset,
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.destroy = oob_destroy,
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.change = oob_tune,
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.dump = oob_dump,
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.owner = THIS_MODULE,
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};
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static int __init oob_module_init(void)
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{
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return register_qdisc(&oob_qdisc_ops);
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}
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static void __exit oob_module_exit(void)
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{
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unregister_qdisc(&oob_qdisc_ops);
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}
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module_init(oob_module_init)
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module_exit(oob_module_exit)
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MODULE_LICENSE("GPL");
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