net/sched/sch_cbs.c - kernel/msm-5.4 - Gitiles

 /*
  * net/sched/sch_cbs.c	Credit Based Shaper
  *
  *		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:	Vinicius Costa Gomes <vinicius.gomes@intel.com>
  *
  */

 /* Credit Based Shaper (CBS)
  * =========================
  *
  * This is a simple rate-limiting shaper aimed at TSN applications on
  * systems with known traffic workloads.
  *
  * Its algorithm is defined by the IEEE 802.1Q-2014 Specification,
  * Section 8.6.8.2, and explained in more detail in the Annex L of the
  * same specification.
  *
  * There are four tunables to be considered:
  *
  *	'idleslope': Idleslope is the rate of credits that is
  *	accumulated (in kilobits per second) when there is at least
  *	one packet waiting for transmission. Packets are transmitted
  *	when the current value of credits is equal or greater than
  *	zero. When there is no packet to be transmitted the amount of
  *	credits is set to zero. This is the main tunable of the CBS
  *	algorithm.
  *
  *	'sendslope':
  *	Sendslope is the rate of credits that is depleted (it should be a
  *	negative number of kilobits per second) when a transmission is
  *	ocurring. It can be calculated as follows, (IEEE 802.1Q-2014 Section
  *	8.6.8.2 item g):
  *
  *	sendslope = idleslope - port_transmit_rate
  *
  *	'hicredit': Hicredit defines the maximum amount of credits (in
  *	bytes) that can be accumulated. Hicredit depends on the
  *	characteristics of interfering traffic,
  *	'max_interference_size' is the maximum size of any burst of
  *	traffic that can delay the transmission of a frame that is
  *	available for transmission for this traffic class, (IEEE
  *	802.1Q-2014 Annex L, Equation L-3):
  *
  *	hicredit = max_interference_size * (idleslope / port_transmit_rate)
  *
  *	'locredit': Locredit is the minimum amount of credits that can
  *	be reached. It is a function of the traffic flowing through
  *	this qdisc (IEEE 802.1Q-2014 Annex L, Equation L-2):
  *
  *	locredit = max_frame_size * (sendslope / port_transmit_rate)
  */

 #include <linux/module.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/sch_generic.h>
 #include <net/pkt_sched.h>

 #define BYTES_PER_KBIT (1000LL / 8)

 struct cbs_sched_data {
 	bool offload;
 	int queue;
 	s64 port_rate; /* in bytes/s */
 	s64 last; /* timestamp in ns */
 	s64 credits; /* in bytes */
 	s32 locredit; /* in bytes */
 	s32 hicredit; /* in bytes */
 	s64 sendslope; /* in bytes/s */
 	s64 idleslope; /* in bytes/s */
 	struct qdisc_watchdog watchdog;
 	int (*enqueue)(struct sk_buff *skb, struct Qdisc *sch);
 	struct sk_buff *(*dequeue)(struct Qdisc *sch);
 };

 static int cbs_enqueue_offload(struct sk_buff *skb, struct Qdisc *sch)
 {
 	return qdisc_enqueue_tail(skb, sch);
 }

 static int cbs_enqueue_soft(struct sk_buff *skb, struct Qdisc *sch)
 {
 	struct cbs_sched_data *q = qdisc_priv(sch);

 	if (sch->q.qlen == 0 && q->credits > 0) {
 		/* We need to stop accumulating credits when there's
 		 * no enqueued packets and q->credits is positive.
 		 */
 		q->credits = 0;
 		q->last = ktime_get_ns();
 	}

 	return qdisc_enqueue_tail(skb, sch);
 }

 static int cbs_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 		       struct sk_buff **to_free)
 {
 	struct cbs_sched_data *q = qdisc_priv(sch);

 	return q->enqueue(skb, sch);
 }

 /* timediff is in ns, slope is in bytes/s */
 static s64 timediff_to_credits(s64 timediff, s64 slope)
 {
 	return div64_s64(timediff * slope, NSEC_PER_SEC);
 }

 static s64 delay_from_credits(s64 credits, s64 slope)
 {
 	if (unlikely(slope == 0))
 		return S64_MAX;

 	return div64_s64(-credits * NSEC_PER_SEC, slope);
 }

 static s64 credits_from_len(unsigned int len, s64 slope, s64 port_rate)
 {
 	if (unlikely(port_rate == 0))
 		return S64_MAX;

 	return div64_s64(len * slope, port_rate);
 }

 static struct sk_buff *cbs_dequeue_soft(struct Qdisc *sch)
 {
 	struct cbs_sched_data *q = qdisc_priv(sch);
 	s64 now = ktime_get_ns();
 	struct sk_buff *skb;
 	s64 credits;
 	int len;

 	if (q->credits < 0) {
 		credits = timediff_to_credits(now - q->last, q->idleslope);

 		credits = q->credits + credits;
 		q->credits = min_t(s64, credits, q->hicredit);

 		if (q->credits < 0) {
 			s64 delay;

 			delay = delay_from_credits(q->credits, q->idleslope);
 			qdisc_watchdog_schedule_ns(&q->watchdog, now + delay);

 			q->last = now;

 			return NULL;
 		}
 	}

 	skb = qdisc_dequeue_head(sch);
 	if (!skb)
 		return NULL;

 	len = qdisc_pkt_len(skb);

 	/* As sendslope is a negative number, this will decrease the
 	 * amount of q->credits.
 	 */
 	credits = credits_from_len(len, q->sendslope, q->port_rate);
 	credits += q->credits;

 	q->credits = max_t(s64, credits, q->locredit);
 	q->last = now;

 	return skb;
 }

 static struct sk_buff *cbs_dequeue_offload(struct Qdisc *sch)
 {
 	return qdisc_dequeue_head(sch);
 }

 static struct sk_buff *cbs_dequeue(struct Qdisc *sch)
 {
 	struct cbs_sched_data *q = qdisc_priv(sch);

 	return q->dequeue(sch);
 }

 static const struct nla_policy cbs_policy[TCA_CBS_MAX + 1] = {
 	[TCA_CBS_PARMS]	= { .len = sizeof(struct tc_cbs_qopt) },
 };

 static void cbs_disable_offload(struct net_device *dev,
 				struct cbs_sched_data *q)
 {
 	struct tc_cbs_qopt_offload cbs = { };
 	const struct net_device_ops *ops;
 	int err;

 	if (!q->offload)
 		return;

 	q->enqueue = cbs_enqueue_soft;
 	q->dequeue = cbs_dequeue_soft;

 	ops = dev->netdev_ops;
 	if (!ops->ndo_setup_tc)
 		return;

 	cbs.queue = q->queue;
 	cbs.enable = 0;

 	err = ops->ndo_setup_tc(dev, TC_SETUP_QDISC_CBS, &cbs);
 	if (err < 0)
 		pr_warn("Couldn't disable CBS offload for queue %d\n",
 			cbs.queue);
 }

 static int cbs_enable_offload(struct net_device *dev, struct cbs_sched_data *q,
 			      const struct tc_cbs_qopt *opt)
 {
 	const struct net_device_ops *ops = dev->netdev_ops;
 	struct tc_cbs_qopt_offload cbs = { };
 	int err;

 	if (!ops->ndo_setup_tc)
 		return -EOPNOTSUPP;

 	cbs.queue = q->queue;

 	cbs.enable = 1;
 	cbs.hicredit = opt->hicredit;
 	cbs.locredit = opt->locredit;
 	cbs.idleslope = opt->idleslope;
 	cbs.sendslope = opt->sendslope;

 	err = ops->ndo_setup_tc(dev, TC_SETUP_QDISC_CBS, &cbs);
 	if (err < 0)
 		return err;

 	q->enqueue = cbs_enqueue_offload;
 	q->dequeue = cbs_dequeue_offload;

 	return 0;
 }

 static int cbs_change(struct Qdisc *sch, struct nlattr *opt)
 {
 	struct cbs_sched_data *q = qdisc_priv(sch);
 	struct net_device *dev = qdisc_dev(sch);
 	struct nlattr *tb[TCA_CBS_MAX + 1];
 	struct tc_cbs_qopt *qopt;
 	int err;

 	err = nla_parse_nested(tb, TCA_CBS_MAX, opt, cbs_policy, NULL);
 	if (err < 0)
 		return err;

 	if (!tb[TCA_CBS_PARMS])
 		return -EINVAL;

 	qopt = nla_data(tb[TCA_CBS_PARMS]);

 	if (!qopt->offload) {
 		struct ethtool_link_ksettings ecmd;
 		s64 link_speed;

 		if (!__ethtool_get_link_ksettings(dev, &ecmd))
 			link_speed = ecmd.base.speed;
 		else
 			link_speed = SPEED_1000;

 		q->port_rate = link_speed * 1000 * BYTES_PER_KBIT;

 		cbs_disable_offload(dev, q);
 	} else {
 		err = cbs_enable_offload(dev, q, qopt);
 		if (err < 0)
 			return err;
 	}

 	/* Everything went OK, save the parameters used. */
 	q->hicredit = qopt->hicredit;
 	q->locredit = qopt->locredit;
 	q->idleslope = qopt->idleslope * BYTES_PER_KBIT;
 	q->sendslope = qopt->sendslope * BYTES_PER_KBIT;
 	q->offload = qopt->offload;

 	return 0;
 }

 static int cbs_init(struct Qdisc *sch, struct nlattr *opt)
 {
 	struct cbs_sched_data *q = qdisc_priv(sch);
 	struct net_device *dev = qdisc_dev(sch);

 	if (!opt)
 		return -EINVAL;

 	q->queue = sch->dev_queue - netdev_get_tx_queue(dev, 0);

 	q->enqueue = cbs_enqueue_soft;
 	q->dequeue = cbs_dequeue_soft;

 	qdisc_watchdog_init(&q->watchdog, sch);

 	return cbs_change(sch, opt);
 }

 static void cbs_destroy(struct Qdisc *sch)
 {
 	struct cbs_sched_data *q = qdisc_priv(sch);
 	struct net_device *dev = qdisc_dev(sch);

 	qdisc_watchdog_cancel(&q->watchdog);

 	cbs_disable_offload(dev, q);
 }

 static int cbs_dump(struct Qdisc *sch, struct sk_buff *skb)
 {
 	struct cbs_sched_data *q = qdisc_priv(sch);
 	struct tc_cbs_qopt opt = { };
 	struct nlattr *nest;

 	nest = nla_nest_start(skb, TCA_OPTIONS);
 	if (!nest)
 		goto nla_put_failure;

 	opt.hicredit = q->hicredit;
 	opt.locredit = q->locredit;
 	opt.sendslope = div64_s64(q->sendslope, BYTES_PER_KBIT);
 	opt.idleslope = div64_s64(q->idleslope, BYTES_PER_KBIT);
 	opt.offload = q->offload;

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

 	return nla_nest_end(skb, nest);

 nla_put_failure:
 	nla_nest_cancel(skb, nest);
 	return -1;
 }

 static struct Qdisc_ops cbs_qdisc_ops __read_mostly = {
 	.id		=	"cbs",
 	.priv_size	=	sizeof(struct cbs_sched_data),
 	.enqueue	=	cbs_enqueue,
 	.dequeue	=	cbs_dequeue,
 	.peek		=	qdisc_peek_dequeued,
 	.init		=	cbs_init,
 	.reset		=	qdisc_reset_queue,
 	.destroy	=	cbs_destroy,
 	.change		=	cbs_change,
 	.dump		=	cbs_dump,
 	.owner		=	THIS_MODULE,
 };

 static int __init cbs_module_init(void)
 {
 	return register_qdisc(&cbs_qdisc_ops);
 }

 static void __exit cbs_module_exit(void)
 {
 	unregister_qdisc(&cbs_qdisc_ops);
 }
 module_init(cbs_module_init)
 module_exit(cbs_module_exit)
 MODULE_LICENSE("GPL");
	/*
	* net/sched/sch_cbs.c Credit Based Shaper
	*
	* 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: Vinicius Costa Gomes <vinicius.gomes@intel.com>
	*
	*/

	/* Credit Based Shaper (CBS)
	* =========================
	*
	* This is a simple rate-limiting shaper aimed at TSN applications on
	* systems with known traffic workloads.
	*
	* Its algorithm is defined by the IEEE 802.1Q-2014 Specification,
	* Section 8.6.8.2, and explained in more detail in the Annex L of the
	* same specification.
	*
	* There are four tunables to be considered:
	*
	* 'idleslope': Idleslope is the rate of credits that is
	* accumulated (in kilobits per second) when there is at least
	* one packet waiting for transmission. Packets are transmitted
	* when the current value of credits is equal or greater than
	* zero. When there is no packet to be transmitted the amount of
	* credits is set to zero. This is the main tunable of the CBS
	* algorithm.
	*
	* 'sendslope':
	* Sendslope is the rate of credits that is depleted (it should be a
	* negative number of kilobits per second) when a transmission is
	* ocurring. It can be calculated as follows, (IEEE 802.1Q-2014 Section
	* 8.6.8.2 item g):
	*
	* sendslope = idleslope - port_transmit_rate
	*
	* 'hicredit': Hicredit defines the maximum amount of credits (in
	* bytes) that can be accumulated. Hicredit depends on the
	* characteristics of interfering traffic,
	* 'max_interference_size' is the maximum size of any burst of
	* traffic that can delay the transmission of a frame that is
	* available for transmission for this traffic class, (IEEE
	* 802.1Q-2014 Annex L, Equation L-3):
	*
	* hicredit = max_interference_size * (idleslope / port_transmit_rate)
	*
	* 'locredit': Locredit is the minimum amount of credits that can
	* be reached. It is a function of the traffic flowing through
	* this qdisc (IEEE 802.1Q-2014 Annex L, Equation L-2):
	*
	* locredit = max_frame_size * (sendslope / port_transmit_rate)
	*/

	#include <linux/module.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/sch_generic.h>
	#include <net/pkt_sched.h>

	#define BYTES_PER_KBIT (1000LL / 8)

	struct cbs_sched_data {
	bool offload;
	int queue;
	s64 port_rate; /* in bytes/s */
	s64 last; /* timestamp in ns */
	s64 credits; /* in bytes */
	s32 locredit; /* in bytes */
	s32 hicredit; /* in bytes */
	s64 sendslope; /* in bytes/s */
	s64 idleslope; /* in bytes/s */
	struct qdisc_watchdog watchdog;
	int (enqueue)(struct sk_buff skb, struct Qdisc *sch);
	struct sk_buff (dequeue)(struct Qdisc *sch);
	};

	static int cbs_enqueue_offload(struct sk_buff skb, struct Qdisc sch)
	{
	return qdisc_enqueue_tail(skb, sch);
	}

	static int cbs_enqueue_soft(struct sk_buff skb, struct Qdisc sch)
	{
	struct cbs_sched_data *q = qdisc_priv(sch);

	if (sch->q.qlen == 0 && q->credits > 0) {
	/* We need to stop accumulating credits when there's
	* no enqueued packets and q->credits is positive.
	*/
	q->credits = 0;
	q->last = ktime_get_ns();
	}

	return qdisc_enqueue_tail(skb, sch);
	}

	static int cbs_enqueue(struct sk_buff skb, struct Qdisc sch,
	struct sk_buff **to_free)
	{
	struct cbs_sched_data *q = qdisc_priv(sch);

	return q->enqueue(skb, sch);
	}

	/* timediff is in ns, slope is in bytes/s */
	static s64 timediff_to_credits(s64 timediff, s64 slope)
	{
	return div64_s64(timediff * slope, NSEC_PER_SEC);
	}

	static s64 delay_from_credits(s64 credits, s64 slope)
	{
	if (unlikely(slope == 0))
	return S64_MAX;

	return div64_s64(-credits * NSEC_PER_SEC, slope);
	}

	static s64 credits_from_len(unsigned int len, s64 slope, s64 port_rate)
	{
	if (unlikely(port_rate == 0))
	return S64_MAX;

	return div64_s64(len * slope, port_rate);
	}

	static struct sk_buff cbs_dequeue_soft(struct Qdisc sch)
	{
	struct cbs_sched_data *q = qdisc_priv(sch);
	s64 now = ktime_get_ns();
	struct sk_buff *skb;
	s64 credits;
	int len;

	if (q->credits < 0) {
	credits = timediff_to_credits(now - q->last, q->idleslope);

	credits = q->credits + credits;
	q->credits = min_t(s64, credits, q->hicredit);

	if (q->credits < 0) {
	s64 delay;

	delay = delay_from_credits(q->credits, q->idleslope);
	qdisc_watchdog_schedule_ns(&q->watchdog, now + delay);

	q->last = now;

	return NULL;
	}
	}

	skb = qdisc_dequeue_head(sch);
	if (!skb)
	return NULL;

	len = qdisc_pkt_len(skb);

	/* As sendslope is a negative number, this will decrease the
	* amount of q->credits.
	*/
	credits = credits_from_len(len, q->sendslope, q->port_rate);
	credits += q->credits;

	q->credits = max_t(s64, credits, q->locredit);
	q->last = now;

	return skb;
	}

	static struct sk_buff cbs_dequeue_offload(struct Qdisc sch)
	{
	return qdisc_dequeue_head(sch);
	}

	static struct sk_buff cbs_dequeue(struct Qdisc sch)
	{
	struct cbs_sched_data *q = qdisc_priv(sch);

	return q->dequeue(sch);
	}

	static const struct nla_policy cbs_policy[TCA_CBS_MAX + 1] = {
	[TCA_CBS_PARMS] = { .len = sizeof(struct tc_cbs_qopt) },
	};

	static void cbs_disable_offload(struct net_device *dev,
	struct cbs_sched_data *q)
	{
	struct tc_cbs_qopt_offload cbs = { };
	const struct net_device_ops *ops;
	int err;

	if (!q->offload)
	return;

	q->enqueue = cbs_enqueue_soft;
	q->dequeue = cbs_dequeue_soft;

	ops = dev->netdev_ops;
	if (!ops->ndo_setup_tc)
	return;

	cbs.queue = q->queue;
	cbs.enable = 0;

	err = ops->ndo_setup_tc(dev, TC_SETUP_QDISC_CBS, &cbs);
	if (err < 0)
	pr_warn("Couldn't disable CBS offload for queue %d\n",
	cbs.queue);
	}

	static int cbs_enable_offload(struct net_device dev, struct cbs_sched_data q,
	const struct tc_cbs_qopt *opt)
	{
	const struct net_device_ops *ops = dev->netdev_ops;
	struct tc_cbs_qopt_offload cbs = { };
	int err;

	if (!ops->ndo_setup_tc)
	return -EOPNOTSUPP;

	cbs.queue = q->queue;

	cbs.enable = 1;
	cbs.hicredit = opt->hicredit;
	cbs.locredit = opt->locredit;
	cbs.idleslope = opt->idleslope;
	cbs.sendslope = opt->sendslope;

	err = ops->ndo_setup_tc(dev, TC_SETUP_QDISC_CBS, &cbs);
	if (err < 0)
	return err;

	q->enqueue = cbs_enqueue_offload;
	q->dequeue = cbs_dequeue_offload;

	return 0;
	}

	static int cbs_change(struct Qdisc sch, struct nlattr opt)
	{
	struct cbs_sched_data *q = qdisc_priv(sch);
	struct net_device *dev = qdisc_dev(sch);
	struct nlattr *tb[TCA_CBS_MAX + 1];
	struct tc_cbs_qopt *qopt;
	int err;

	err = nla_parse_nested(tb, TCA_CBS_MAX, opt, cbs_policy, NULL);
	if (err < 0)
	return err;

	if (!tb[TCA_CBS_PARMS])
	return -EINVAL;

	qopt = nla_data(tb[TCA_CBS_PARMS]);

	if (!qopt->offload) {
	struct ethtool_link_ksettings ecmd;
	s64 link_speed;

	if (!__ethtool_get_link_ksettings(dev, &ecmd))
	link_speed = ecmd.base.speed;
	else
	link_speed = SPEED_1000;

	q->port_rate = link_speed * 1000 * BYTES_PER_KBIT;

	cbs_disable_offload(dev, q);
	} else {
	err = cbs_enable_offload(dev, q, qopt);
	if (err < 0)
	return err;
	}

	/* Everything went OK, save the parameters used. */
	q->hicredit = qopt->hicredit;
	q->locredit = qopt->locredit;
	q->idleslope = qopt->idleslope * BYTES_PER_KBIT;
	q->sendslope = qopt->sendslope * BYTES_PER_KBIT;
	q->offload = qopt->offload;

	return 0;
	}

	static int cbs_init(struct Qdisc sch, struct nlattr opt)
	{
	struct cbs_sched_data *q = qdisc_priv(sch);
	struct net_device *dev = qdisc_dev(sch);

	if (!opt)
	return -EINVAL;

	q->queue = sch->dev_queue - netdev_get_tx_queue(dev, 0);

	q->enqueue = cbs_enqueue_soft;
	q->dequeue = cbs_dequeue_soft;

	qdisc_watchdog_init(&q->watchdog, sch);

	return cbs_change(sch, opt);
	}

	static void cbs_destroy(struct Qdisc *sch)
	{
	struct cbs_sched_data *q = qdisc_priv(sch);
	struct net_device *dev = qdisc_dev(sch);

	qdisc_watchdog_cancel(&q->watchdog);

	cbs_disable_offload(dev, q);
	}

	static int cbs_dump(struct Qdisc sch, struct sk_buff skb)
	{
	struct cbs_sched_data *q = qdisc_priv(sch);
	struct tc_cbs_qopt opt = { };
	struct nlattr *nest;

	nest = nla_nest_start(skb, TCA_OPTIONS);
	if (!nest)
	goto nla_put_failure;

	opt.hicredit = q->hicredit;
	opt.locredit = q->locredit;
	opt.sendslope = div64_s64(q->sendslope, BYTES_PER_KBIT);
	opt.idleslope = div64_s64(q->idleslope, BYTES_PER_KBIT);
	opt.offload = q->offload;

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

	return nla_nest_end(skb, nest);

	nla_put_failure:
	nla_nest_cancel(skb, nest);
	return -1;
	}

	static struct Qdisc_ops cbs_qdisc_ops __read_mostly = {
	.id = "cbs",
	.priv_size = sizeof(struct cbs_sched_data),
	.enqueue = cbs_enqueue,
	.dequeue = cbs_dequeue,
	.peek = qdisc_peek_dequeued,
	.init = cbs_init,
	.reset = qdisc_reset_queue,
	.destroy = cbs_destroy,
	.change = cbs_change,
	.dump = cbs_dump,
	.owner = THIS_MODULE,
	};

	static int __init cbs_module_init(void)
	{
	return register_qdisc(&cbs_qdisc_ops);
	}

	static void __exit cbs_module_exit(void)
	{
	unregister_qdisc(&cbs_qdisc_ops);
	}
	module_init(cbs_module_init)
	module_exit(cbs_module_exit)
	MODULE_LICENSE("GPL");