/*
 * net/sched/sch_prio.c	Simple 3-band priority "scheduler".
 *
 *		This program is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or (at your option) any later version.
 *
 * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
 * Fixes:       19990609: J Hadi Salim <hadi@nortelnetworks.com>:
 *              Init --  EINVAL when opt undefined
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <net/netlink.h>
#include <net/pkt_sched.h>
#include <net/pkt_cls.h>

struct prio_sched_data {
	int bands;
	struct tcf_proto __rcu *filter_list;
	u8  prio2band[TC_PRIO_MAX+1];
	struct Qdisc *queues[TCQ_PRIO_BANDS];
};


static struct Qdisc *
prio_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr)
{
	struct prio_sched_data *q = qdisc_priv(sch);
	u32 band = skb->priority;
	struct tcf_result res;
	struct tcf_proto *fl;
	int err;

	*qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
	if (TC_H_MAJ(skb->priority) != sch->handle) {
		fl = rcu_dereference_bh(q->filter_list);
		err = tc_classify(skb, fl, &res, false);
#ifdef CONFIG_NET_CLS_ACT
		switch (err) {
		case TC_ACT_STOLEN:
		case TC_ACT_QUEUED:
			*qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
		case TC_ACT_SHOT:
			return NULL;
		}
#endif
		if (!fl || err < 0) {
			if (TC_H_MAJ(band))
				band = 0;
			return q->queues[q->prio2band[band & TC_PRIO_MAX]];
		}
		band = res.classid;
	}
	band = TC_H_MIN(band) - 1;
	if (band >= q->bands)
		return q->queues[q->prio2band[0]];

	return q->queues[band];
}

static int
prio_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free)
{
	struct Qdisc *qdisc;
	int ret;

	qdisc = prio_classify(skb, sch, &ret);
#ifdef CONFIG_NET_CLS_ACT
	if (qdisc == NULL) {

		if (ret & __NET_XMIT_BYPASS)
			qdisc_qstats_drop(sch);
		kfree_skb(skb);
		return ret;
	}
#endif

	ret = qdisc_enqueue(skb, qdisc, to_free);
	if (ret == NET_XMIT_SUCCESS) {
		qdisc_qstats_backlog_inc(sch, skb);
		sch->q.qlen++;
		return NET_XMIT_SUCCESS;
	}
	if (net_xmit_drop_count(ret))
		qdisc_qstats_drop(sch);
	return ret;
}

static struct sk_buff *prio_peek(struct Qdisc *sch)
{
	struct prio_sched_data *q = qdisc_priv(sch);
	int prio;

	for (prio = 0; prio < q->bands; prio++) {
		struct Qdisc *qdisc = q->queues[prio];
		struct sk_buff *skb = qdisc->ops->peek(qdisc);
		if (skb)
			return skb;
	}
	return NULL;
}

static struct sk_buff *prio_dequeue(struct Qdisc *sch)
{
	struct prio_sched_data *q = qdisc_priv(sch);
	int prio;

	for (prio = 0; prio < q->bands; prio++) {
		struct Qdisc *qdisc = q->queues[prio];
		struct sk_buff *skb = qdisc_dequeue_peeked(qdisc);
		if (skb) {
			qdisc_bstats_update(sch, skb);
			qdisc_qstats_backlog_dec(sch, skb);
			sch->q.qlen--;
			return skb;
		}
	}
	return NULL;

}

static void
prio_reset(struct Qdisc *sch)
{
	int prio;
	struct prio_sched_data *q = qdisc_priv(sch);

	for (prio = 0; prio < q->bands; prio++)
		qdisc_reset(q->queues[prio]);
	sch->qstats.backlog = 0;
	sch->q.qlen = 0;
}

static void
prio_destroy(struct Qdisc *sch)
{
	int prio;
	struct prio_sched_data *q = qdisc_priv(sch);

	tcf_destroy_chain(&q->filter_list);
	for (prio = 0; prio < q->bands; prio++)
		qdisc_destroy(q->queues[prio]);
}

static int prio_tune(struct Qdisc *sch, struct nlattr *opt)
{
	struct prio_sched_data *q = qdisc_priv(sch);
	struct Qdisc *queues[TCQ_PRIO_BANDS];
	int oldbands = q->bands, i;
	struct tc_prio_qopt *qopt;

	if (nla_len(opt) < sizeof(*qopt))
		return -EINVAL;
	qopt = nla_data(opt);

	if (qopt->bands > TCQ_PRIO_BANDS || qopt->bands < 2)
		return -EINVAL;

	for (i = 0; i <= TC_PRIO_MAX; i++) {
		if (qopt->priomap[i] >= qopt->bands)
			return -EINVAL;
	}

	/* Before commit, make sure we can allocate all new qdiscs */
	for (i = oldbands; i < qopt->bands; i++) {
		queues[i] = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
					      TC_H_MAKE(sch->handle, i + 1));
		if (!queues[i]) {
			while (i > oldbands)
				qdisc_destroy(queues[--i]);
			return -ENOMEM;
		}
	}

	sch_tree_lock(sch);
	q->bands = qopt->bands;
	memcpy(q->prio2band, qopt->priomap, TC_PRIO_MAX+1);

	for (i = q->bands; i < oldbands; i++) {
		struct Qdisc *child = q->queues[i];

		qdisc_tree_reduce_backlog(child, child->q.qlen,
					  child->qstats.backlog);
		qdisc_destroy(child);
	}

	for (i = oldbands; i < q->bands; i++)
		q->queues[i] = queues[i];

	sch_tree_unlock(sch);
	return 0;
}

static int prio_init(struct Qdisc *sch, struct nlattr *opt)
{
	if (!opt)
		return -EINVAL;

	return prio_tune(sch, opt);
}

static int prio_dump(struct Qdisc *sch, struct sk_buff *skb)
{
	struct prio_sched_data *q = qdisc_priv(sch);
	unsigned char *b = skb_tail_pointer(skb);
	struct tc_prio_qopt opt;

	opt.bands = q->bands;
	memcpy(&opt.priomap, q->prio2band, TC_PRIO_MAX + 1);

	if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
		goto nla_put_failure;

	return skb->len;

nla_put_failure:
	nlmsg_trim(skb, b);
	return -1;
}

static int prio_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
		      struct Qdisc **old)
{
	struct prio_sched_data *q = qdisc_priv(sch);
	unsigned long band = arg - 1;

	if (new == NULL)
		new = &noop_qdisc;

	*old = qdisc_replace(sch, new, &q->queues[band]);
	return 0;
}

static struct Qdisc *
prio_leaf(struct Qdisc *sch, unsigned long arg)
{
	struct prio_sched_data *q = qdisc_priv(sch);
	unsigned long band = arg - 1;

	return q->queues[band];
}

static unsigned long prio_get(struct Qdisc *sch, u32 classid)
{
	struct prio_sched_data *q = qdisc_priv(sch);
	unsigned long band = TC_H_MIN(classid);

	if (band - 1 >= q->bands)
		return 0;
	return band;
}

static unsigned long prio_bind(struct Qdisc *sch, unsigned long parent, u32 classid)
{
	return prio_get(sch, classid);
}


static void prio_put(struct Qdisc *q, unsigned long cl)
{
}

static int prio_dump_class(struct Qdisc *sch, unsigned long cl, struct sk_buff *skb,
			   struct tcmsg *tcm)
{
	struct prio_sched_data *q = qdisc_priv(sch);

	tcm->tcm_handle |= TC_H_MIN(cl);
	tcm->tcm_info = q->queues[cl-1]->handle;
	return 0;
}

static int prio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
				 struct gnet_dump *d)
{
	struct prio_sched_data *q = qdisc_priv(sch);
	struct Qdisc *cl_q;

	cl_q = q->queues[cl - 1];
	if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch),
				  d, NULL, &cl_q->bstats) < 0 ||
	    gnet_stats_copy_queue(d, NULL, &cl_q->qstats, cl_q->q.qlen) < 0)
		return -1;

	return 0;
}

static void prio_walk(struct Qdisc *sch, struct qdisc_walker *arg)
{
	struct prio_sched_data *q = qdisc_priv(sch);
	int prio;

	if (arg->stop)
		return;

	for (prio = 0; prio < q->bands; prio++) {
		if (arg->count < arg->skip) {
			arg->count++;
			continue;
		}
		if (arg->fn(sch, prio + 1, arg) < 0) {
			arg->stop = 1;
			break;
		}
		arg->count++;
	}
}

static struct tcf_proto __rcu **prio_find_tcf(struct Qdisc *sch,
					      unsigned long cl)
{
	struct prio_sched_data *q = qdisc_priv(sch);

	if (cl)
		return NULL;
	return &q->filter_list;
}

static const struct Qdisc_class_ops prio_class_ops = {
	.graft		=	prio_graft,
	.leaf		=	prio_leaf,
	.get		=	prio_get,
	.put		=	prio_put,
	.walk		=	prio_walk,
	.tcf_chain	=	prio_find_tcf,
	.bind_tcf	=	prio_bind,
	.unbind_tcf	=	prio_put,
	.dump		=	prio_dump_class,
	.dump_stats	=	prio_dump_class_stats,
};

static struct Qdisc_ops prio_qdisc_ops __read_mostly = {
	.next		=	NULL,
	.cl_ops		=	&prio_class_ops,
	.id		=	"prio",
	.priv_size	=	sizeof(struct prio_sched_data),
	.enqueue	=	prio_enqueue,
	.dequeue	=	prio_dequeue,
	.peek		=	prio_peek,
	.init		=	prio_init,
	.reset		=	prio_reset,
	.destroy	=	prio_destroy,
	.change		=	prio_tune,
	.dump		=	prio_dump,
	.owner		=	THIS_MODULE,
};

static int __init prio_module_init(void)
{
	return register_qdisc(&prio_qdisc_ops);
}

static void __exit prio_module_exit(void)
{
	unregister_qdisc(&prio_qdisc_ops);
}

module_init(prio_module_init)
module_exit(prio_module_exit)

MODULE_LICENSE("GPL");
 only one filter, and there is no
situation where one exists and the other does not. In addition, that led
to some races when filter was deleted while packet was processed.

Unify that two structs into one, thus simplifying the process of matchall
creation and deletion. As a result, the new, delete and get callbacks have
a dummy implementation where all the work is done in destroy and change
callbacks, as was done in cls_cgroup.

Fixes: bf3994d2ed31 ("net/sched: introduce Match-all classifier")
Reported-by: Daniel Borkmann &lt;daniel@iogearbox.net&gt;
Signed-off-by: Yotam Gigi &lt;yotamg@mellanox.com&gt;
Acked-by: Jiri Pirko &lt;jiri@mellanox.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;


</td></tr>