[linux-block.git] / net / sched / sch_cbs.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * net/sched/sch_cbs.c	Credit Based Shaper
 *
 * 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/netevent.h>
#include <net/netlink.h>
#include <net/sch_generic.h>
#include <net/pkt_sched.h>

static LIST_HEAD(cbs_list);
static DEFINE_SPINLOCK(cbs_list_lock);

#define BYTES_PER_KBIT (1000LL / 8)

struct cbs_sched_data {
	bool offload;
	int queue;
	atomic64_t 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 **to_free);
	struct sk_buff *(*dequeue)(struct Qdisc *sch);
	struct Qdisc *qdisc;
	struct list_head cbs_list;
};

static int cbs_child_enqueue(struct sk_buff *skb, struct Qdisc *sch,
			     struct Qdisc *child,
			     struct sk_buff **to_free)
{
	unsigned int len = qdisc_pkt_len(skb);
	int err;

	err = child->ops->enqueue(skb, child, to_free);
	if (err != NET_XMIT_SUCCESS)
		return err;

	sch->qstats.backlog += len;
	sch->q.qlen++;

	return NET_XMIT_SUCCESS;
}

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
		 * no enqueued packets and q->credits is positive.
		 */
		q->credits = 0;
		q->last = ktime_get_ns();
	}

	return cbs_child_enqueue(skb, sch, qdisc, to_free);
}

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, to_free);
}

/* 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_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;
	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 = cbs_child_dequeue(sch, qdisc);
	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,
				   atomic64_read(&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)
{
	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)
{
	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,
			      struct netlink_ext_ack *extack)
{
	const struct net_device_ops *ops = dev->netdev_ops;
	struct tc_cbs_qopt_offload cbs = { };
	int err;

	if (!ops->ndo_setup_tc) {
		NL_SET_ERR_MSG(extack, "Specified device does not support cbs offload");
		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) {
		NL_SET_ERR_MSG(extack, "Specified device failed to setup cbs hardware offload");
		return err;
	}

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

	return 0;
}

static void cbs_set_port_rate(struct net_device *dev, struct cbs_sched_data *q)
{
	struct ethtool_link_ksettings ecmd;
	int speed = SPEED_10;
	int port_rate;
	int err;

	err = __ethtool_get_link_ksettings(dev, &ecmd);
	if (err < 0)
		goto skip;

	if (ecmd.base.speed && ecmd.base.speed != SPEED_UNKNOWN)
		speed = ecmd.base.speed;

skip:
	port_rate = speed * 1000 * BYTES_PER_KBIT;

	atomic64_set(&q->port_rate, port_rate);
	netdev_dbg(dev, "cbs: set %s's port_rate to: %lld, linkspeed: %d\n",
		   dev->name, (long long)atomic64_read(&q->port_rate),
		   ecmd.base.speed);
}

static int cbs_dev_notifier(struct notifier_block *nb, unsigned long event,
			    void *ptr)
{
	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
	struct cbs_sched_data *q;
	struct net_device *qdev;
	bool found = false;

	ASSERT_RTNL();

	if (event != NETDEV_UP && event != NETDEV_CHANGE)
		return NOTIFY_DONE;

	spin_lock(&cbs_list_lock);
	list_for_each_entry(q, &cbs_list, cbs_list) {
		qdev = qdisc_dev(q->qdisc);
		if (qdev == dev) {
			found = true;
			break;
		}
	}
	spin_unlock(&cbs_list_lock);

	if (found)
		cbs_set_port_rate(dev, q);

	return NOTIFY_DONE;
}

static int cbs_change(struct Qdisc *sch, struct nlattr *opt,
		      struct netlink_ext_ack *extack)
{
	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_deprecated(tb, TCA_CBS_MAX, opt, cbs_policy,
					  extack);
	if (err < 0)
		return err;

	if (!tb[TCA_CBS_PARMS]) {
		NL_SET_ERR_MSG(extack, "Missing CBS parameter which are mandatory");
		return -EINVAL;
	}

	qopt = nla_data(tb[TCA_CBS_PARMS]);

	if (!qopt->offload) {
		cbs_set_port_rate(dev, q);
		cbs_disable_offload(dev, q);
	} else {
		err = cbs_enable_offload(dev, q, qopt, extack);
		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 netlink_ext_ack *extack)
{
	struct cbs_sched_data *q = qdisc_priv(sch);
	struct net_device *dev = qdisc_dev(sch);

	if (!opt) {
		NL_SET_ERR_MSG(extack, "Missing CBS qdisc options  which are mandatory");
		return -EINVAL;
	}

	q->qdisc = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
				     sch->handle, extack);
	if (!q->qdisc)
		return -ENOMEM;

	spin_lock(&cbs_list_lock);
	list_add(&q->cbs_list, &cbs_list);
	spin_unlock(&cbs_list_lock);

	qdisc_hash_add(q->qdisc, false);

	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, extack);
}

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

	/* Nothing to do if we couldn't create the underlying qdisc */
	if (!q->qdisc)
		return;

	qdisc_watchdog_cancel(&q->watchdog);
	cbs_disable_offload(dev, q);

	spin_lock(&cbs_list_lock);
	list_del(&q->cbs_list);
	spin_unlock(&cbs_list_lock);

	qdisc_put(q->qdisc);
}

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_noflag(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 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,
	.peek		=	qdisc_peek_dequeued,
	.init		=	cbs_init,
	.reset		=	qdisc_reset_queue,
	.destroy	=	cbs_destroy,
	.change		=	cbs_change,
	.dump		=	cbs_dump,
	.owner		=	THIS_MODULE,
};

static struct notifier_block cbs_device_notifier = {
	.notifier_call = cbs_dev_notifier,
};

static int __init cbs_module_init(void)
{
	int err;

	err = register_netdevice_notifier(&cbs_device_notifier);
	if (err)
		return err;

	err = register_qdisc(&cbs_qdisc_ops);
	if (err)
		unregister_netdevice_notifier(&cbs_device_notifier);

	return err;
}

static void __exit cbs_module_exit(void)
{
	unregister_qdisc(&cbs_qdisc_ops);
	unregister_netdevice_notifier(&cbs_device_notifier);
}
module_init(cbs_module_init)
module_exit(cbs_module_exit)
MODULE_LICENSE("GPL");
Commit	Line	Data
2874c5fd	1	// SPDX-License-Identifier: GPL-2.0-or-later
585d763a VCG	2	/*
	3	* net/sched/sch_cbs.c Credit Based Shaper
	4	*
585d763a	5	* Authors: Vinicius Costa Gomes <vinicius.gomes@intel.com>
585d763a VCG	6	*/
	7
	8	/* Credit Based Shaper (CBS)
	9	* =========================
	10	*
	11	* This is a simple rate-limiting shaper aimed at TSN applications on
	12	* systems with known traffic workloads.
	13	*
	14	* Its algorithm is defined by the IEEE 802.1Q-2014 Specification,
	15	* Section 8.6.8.2, and explained in more detail in the Annex L of the
	16	* same specification.
	17	*
	18	* There are four tunables to be considered:
	19	*
	20	* 'idleslope': Idleslope is the rate of credits that is
	21	* accumulated (in kilobits per second) when there is at least
	22	* one packet waiting for transmission. Packets are transmitted
	23	* when the current value of credits is equal or greater than
	24	* zero. When there is no packet to be transmitted the amount of
	25	* credits is set to zero. This is the main tunable of the CBS
	26	* algorithm.
	27	*
	28	* 'sendslope':
	29	* Sendslope is the rate of credits that is depleted (it should be a
	30	* negative number of kilobits per second) when a transmission is
	31	* ocurring. It can be calculated as follows, (IEEE 802.1Q-2014 Section
	32	* 8.6.8.2 item g):
	33	*
	34	* sendslope = idleslope - port_transmit_rate
	35	*
	36	* 'hicredit': Hicredit defines the maximum amount of credits (in
	37	* bytes) that can be accumulated. Hicredit depends on the
	38	* characteristics of interfering traffic,
	39	* 'max_interference_size' is the maximum size of any burst of
	40	* traffic that can delay the transmission of a frame that is
	41	* available for transmission for this traffic class, (IEEE
	42	* 802.1Q-2014 Annex L, Equation L-3):
	43	*
	44	* hicredit = max_interference_size * (idleslope / port_transmit_rate)
	45	*
	46	* 'locredit': Locredit is the minimum amount of credits that can
	47	* be reached. It is a function of the traffic flowing through
	48	* this qdisc (IEEE 802.1Q-2014 Annex L, Equation L-2):
	49	*
	50	* locredit = max_frame_size * (sendslope / port_transmit_rate)
	51	*/
	52
	53	#include <linux/module.h>
	54	#include <linux/types.h>
	55	#include <linux/kernel.h>
	56	#include <linux/string.h>
	57	#include <linux/errno.h>
	58	#include <linux/skbuff.h>
e0a7683d	59	#include <net/netevent.h>
585d763a VCG	60	#include <net/netlink.h>
	61	#include <net/sch_generic.h>
	62	#include <net/pkt_sched.h>
	63
e0a7683d LD	64	static LIST_HEAD(cbs_list);
	65	static DEFINE_SPINLOCK(cbs_list_lock);
	66
585d763a VCG	67	#define BYTES_PER_KBIT (1000LL / 8)
	68
	69	struct cbs_sched_data {
3d0bd028 VCG	70	bool offload;
3d0bd028 VCG	71	int queue;
e0a7683d	72	atomic64_t port_rate; /* in bytes/s */
585d763a VCG	73	s64 last; /* timestamp in ns */
	74	s64 credits; /* in bytes */
	75	s32 locredit; /* in bytes */
	76	s32 hicredit; /* in bytes */
	77	s64 sendslope; /* in bytes/s */
	78	s64 idleslope; /* in bytes/s */
	79	struct qdisc_watchdog watchdog;
990e35ec VCG	80	int (enqueue)(struct sk_buff skb, struct Qdisc *sch,
990e35ec VCG	81	struct sk_buff **to_free);
585d763a	82	struct sk_buff (dequeue)(struct Qdisc *sch);
990e35ec	83	struct Qdisc *qdisc;
e0a7683d	84	struct list_head cbs_list;
585d763a VCG	85	};
585d763a VCG	86
990e35ec VCG	87	static int cbs_child_enqueue(struct sk_buff skb, struct Qdisc sch,
	88	struct Qdisc *child,
	89	struct sk_buff **to_free)
3d0bd028	90	{
f6bab199	91	unsigned int len = qdisc_pkt_len(skb);
990e35ec VCG	92	int err;
	93
	94	err = child->ops->enqueue(skb, child, to_free);
	95	if (err != NET_XMIT_SUCCESS)
	96	return err;
	97
f6bab199	98	sch->qstats.backlog += len;
990e35ec VCG	99	sch->q.qlen++;
	100
	101	return NET_XMIT_SUCCESS;
3d0bd028 VCG	102	}
3d0bd028 VCG	103
990e35ec VCG	104	static int cbs_enqueue_offload(struct sk_buff skb, struct Qdisc sch,
990e35ec VCG	105	struct sk_buff **to_free)
585d763a VCG	106	{
585d763a VCG	107	struct cbs_sched_data *q = qdisc_priv(sch);
990e35ec VCG	108	struct Qdisc *qdisc = q->qdisc;
	109
	110	return cbs_child_enqueue(skb, sch, qdisc, to_free);
	111	}
	112
	113	static int cbs_enqueue_soft(struct sk_buff skb, struct Qdisc sch,
	114	struct sk_buff **to_free)
	115	{
	116	struct cbs_sched_data *q = qdisc_priv(sch);
	117	struct Qdisc *qdisc = q->qdisc;
585d763a VCG	118
	119	if (sch->q.qlen == 0 && q->credits > 0) {
	120	/* We need to stop accumulating credits when there's
	121	* no enqueued packets and q->credits is positive.
	122	*/
	123	q->credits = 0;
	124	q->last = ktime_get_ns();
	125	}
	126
990e35ec	127	return cbs_child_enqueue(skb, sch, qdisc, to_free);
585d763a VCG	128	}
	129
	130	static int cbs_enqueue(struct sk_buff skb, struct Qdisc sch,
	131	struct sk_buff **to_free)
	132	{
	133	struct cbs_sched_data *q = qdisc_priv(sch);
	134
990e35ec	135	return q->enqueue(skb, sch, to_free);
585d763a VCG	136	}
	137
	138	/* timediff is in ns, slope is in bytes/s */
	139	static s64 timediff_to_credits(s64 timediff, s64 slope)
	140	{
	141	return div64_s64(timediff * slope, NSEC_PER_SEC);
	142	}
	143
	144	static s64 delay_from_credits(s64 credits, s64 slope)
	145	{
	146	if (unlikely(slope == 0))
	147	return S64_MAX;
	148
	149	return div64_s64(-credits * NSEC_PER_SEC, slope);
	150	}
	151
	152	static s64 credits_from_len(unsigned int len, s64 slope, s64 port_rate)
	153	{
	154	if (unlikely(port_rate == 0))
	155	return S64_MAX;
	156
	157	return div64_s64(len * slope, port_rate);
	158	}
	159
990e35ec VCG	160	static struct sk_buff cbs_child_dequeue(struct Qdisc sch, struct Qdisc *child)
	161	{
	162	struct sk_buff *skb;
	163
	164	skb = child->ops->dequeue(child);
	165	if (!skb)
	166	return NULL;
	167
	168	qdisc_qstats_backlog_dec(sch, skb);
	169	qdisc_bstats_update(sch, skb);
	170	sch->q.qlen--;
	171
	172	return skb;
	173	}
	174
585d763a VCG	175	static struct sk_buff cbs_dequeue_soft(struct Qdisc sch)
	176	{
	177	struct cbs_sched_data *q = qdisc_priv(sch);
990e35ec	178	struct Qdisc *qdisc = q->qdisc;
585d763a VCG	179	s64 now = ktime_get_ns();
	180	struct sk_buff *skb;
	181	s64 credits;
	182	int len;
	183
	184	if (q->credits < 0) {
	185	credits = timediff_to_credits(now - q->last, q->idleslope);
	186
	187	credits = q->credits + credits;
	188	q->credits = min_t(s64, credits, q->hicredit);
	189
	190	if (q->credits < 0) {
	191	s64 delay;
	192
	193	delay = delay_from_credits(q->credits, q->idleslope);
	194	qdisc_watchdog_schedule_ns(&q->watchdog, now + delay);
	195
	196	q->last = now;
	197
	198	return NULL;
	199	}
	200	}
990e35ec	201	skb = cbs_child_dequeue(sch, qdisc);
585d763a VCG	202	if (!skb)
	203	return NULL;
	204
	205	len = qdisc_pkt_len(skb);
	206
	207	/* As sendslope is a negative number, this will decrease the
	208	* amount of q->credits.
	209	*/
e0a7683d LD	210	credits = credits_from_len(len, q->sendslope,
e0a7683d LD	211	atomic64_read(&q->port_rate));
585d763a VCG	212	credits += q->credits;
	213
	214	q->credits = max_t(s64, credits, q->locredit);
	215	q->last = now;
	216
	217	return skb;
	218	}
	219
3d0bd028 VCG	220	static struct sk_buff cbs_dequeue_offload(struct Qdisc sch)
3d0bd028 VCG	221	{
990e35ec VCG	222	struct cbs_sched_data *q = qdisc_priv(sch);
	223	struct Qdisc *qdisc = q->qdisc;
	224
	225	return cbs_child_dequeue(sch, qdisc);
3d0bd028 VCG	226	}
3d0bd028 VCG	227
585d763a VCG	228	static struct sk_buff cbs_dequeue(struct Qdisc sch)
	229	{
	230	struct cbs_sched_data *q = qdisc_priv(sch);
	231
	232	return q->dequeue(sch);
	233	}
	234
	235	static const struct nla_policy cbs_policy[TCA_CBS_MAX + 1] = {
	236	[TCA_CBS_PARMS] = { .len = sizeof(struct tc_cbs_qopt) },
	237	};
	238
3d0bd028 VCG	239	static void cbs_disable_offload(struct net_device *dev,
	240	struct cbs_sched_data *q)
	241	{
	242	struct tc_cbs_qopt_offload cbs = { };
	243	const struct net_device_ops *ops;
	244	int err;
	245
	246	if (!q->offload)
	247	return;
	248
	249	q->enqueue = cbs_enqueue_soft;
	250	q->dequeue = cbs_dequeue_soft;
	251
	252	ops = dev->netdev_ops;
	253	if (!ops->ndo_setup_tc)
	254	return;
	255
	256	cbs.queue = q->queue;
	257	cbs.enable = 0;
	258
8521db4c	259	err = ops->ndo_setup_tc(dev, TC_SETUP_QDISC_CBS, &cbs);
3d0bd028 VCG	260	if (err < 0)
	261	pr_warn("Couldn't disable CBS offload for queue %d\n",
	262	cbs.queue);
	263	}
	264
	265	static int cbs_enable_offload(struct net_device dev, struct cbs_sched_data q,
710fb396 AA	266	const struct tc_cbs_qopt *opt,
710fb396 AA	267	struct netlink_ext_ack *extack)
3d0bd028 VCG	268	{
	269	const struct net_device_ops *ops = dev->netdev_ops;
	270	struct tc_cbs_qopt_offload cbs = { };
	271	int err;
	272
710fb396 AA	273	if (!ops->ndo_setup_tc) {
710fb396 AA	274	NL_SET_ERR_MSG(extack, "Specified device does not support cbs offload");
3d0bd028	275	return -EOPNOTSUPP;
710fb396	276	}
3d0bd028 VCG	277
	278	cbs.queue = q->queue;
	279
	280	cbs.enable = 1;
	281	cbs.hicredit = opt->hicredit;
	282	cbs.locredit = opt->locredit;
	283	cbs.idleslope = opt->idleslope;
	284	cbs.sendslope = opt->sendslope;
	285
8521db4c	286	err = ops->ndo_setup_tc(dev, TC_SETUP_QDISC_CBS, &cbs);
710fb396 AA	287	if (err < 0) {
710fb396 AA	288	NL_SET_ERR_MSG(extack, "Specified device failed to setup cbs hardware offload");
3d0bd028	289	return err;
710fb396	290	}
3d0bd028 VCG	291
	292	q->enqueue = cbs_enqueue_offload;
	293	q->dequeue = cbs_dequeue_offload;
	294
	295	return 0;
	296	}
	297
e0a7683d LD	298	static void cbs_set_port_rate(struct net_device dev, struct cbs_sched_data q)
	299	{
	300	struct ethtool_link_ksettings ecmd;
1c6c09a0	301	int speed = SPEED_10;
9367fa08	302	int port_rate;
1c6c09a0 VO	303	int err;
	304
	305	err = __ethtool_get_link_ksettings(dev, &ecmd);
	306	if (err < 0)
	307	goto skip;
	308
83c8c3cf	309	if (ecmd.base.speed && ecmd.base.speed != SPEED_UNKNOWN)
1c6c09a0	310	speed = ecmd.base.speed;
e0a7683d	311
1c6c09a0 VO	312	skip:
1c6c09a0 VO	313	port_rate = speed * 1000 * BYTES_PER_KBIT;
e0a7683d LD	314
	315	atomic64_set(&q->port_rate, port_rate);
	316	netdev_dbg(dev, "cbs: set %s's port_rate to: %lld, linkspeed: %d\n",
	317	dev->name, (long long)atomic64_read(&q->port_rate),
	318	ecmd.base.speed);
	319	}
	320
	321	static int cbs_dev_notifier(struct notifier_block *nb, unsigned long event,
	322	void *ptr)
	323	{
	324	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
	325	struct cbs_sched_data *q;
	326	struct net_device *qdev;
	327	bool found = false;
	328
	329	ASSERT_RTNL();
	330
	331	if (event != NETDEV_UP && event != NETDEV_CHANGE)
	332	return NOTIFY_DONE;
	333
	334	spin_lock(&cbs_list_lock);
	335	list_for_each_entry(q, &cbs_list, cbs_list) {
	336	qdev = qdisc_dev(q->qdisc);
	337	if (qdev == dev) {
	338	found = true;
	339	break;
	340	}
	341	}
	342	spin_unlock(&cbs_list_lock);
	343
	344	if (found)
	345	cbs_set_port_rate(dev, q);
	346
	347	return NOTIFY_DONE;
	348	}
	349
2030721c AA	350	static int cbs_change(struct Qdisc sch, struct nlattr opt,
2030721c AA	351	struct netlink_ext_ack *extack)
585d763a VCG	352	{
	353	struct cbs_sched_data *q = qdisc_priv(sch);
	354	struct net_device *dev = qdisc_dev(sch);
	355	struct nlattr *tb[TCA_CBS_MAX + 1];
585d763a	356	struct tc_cbs_qopt *qopt;
585d763a VCG	357	int err;
585d763a VCG	358
8cb08174 JB	359	err = nla_parse_nested_deprecated(tb, TCA_CBS_MAX, opt, cbs_policy,
8cb08174 JB	360	extack);
585d763a VCG	361	if (err < 0)
	362	return err;
	363
710fb396 AA	364	if (!tb[TCA_CBS_PARMS]) {
710fb396 AA	365	NL_SET_ERR_MSG(extack, "Missing CBS parameter which are mandatory");
585d763a	366	return -EINVAL;
710fb396	367	}
585d763a VCG	368
	369	qopt = nla_data(tb[TCA_CBS_PARMS]);
	370
3d0bd028	371	if (!qopt->offload) {
e0a7683d	372	cbs_set_port_rate(dev, q);
3d0bd028 VCG	373	cbs_disable_offload(dev, q);
3d0bd028 VCG	374	} else {
710fb396	375	err = cbs_enable_offload(dev, q, qopt, extack);
3d0bd028 VCG	376	if (err < 0)
	377	return err;
	378	}
585d763a	379
3d0bd028	380	/* Everything went OK, save the parameters used. */
585d763a VCG	381	q->hicredit = qopt->hicredit;
	382	q->locredit = qopt->locredit;
	383	q->idleslope = qopt->idleslope * BYTES_PER_KBIT;
	384	q->sendslope = qopt->sendslope * BYTES_PER_KBIT;
3d0bd028	385	q->offload = qopt->offload;
585d763a VCG	386
	387	return 0;
	388	}
	389
e63d7dfd AA	390	static int cbs_init(struct Qdisc sch, struct nlattr opt,
e63d7dfd AA	391	struct netlink_ext_ack *extack)
585d763a VCG	392	{
585d763a VCG	393	struct cbs_sched_data *q = qdisc_priv(sch);
3d0bd028	394	struct net_device *dev = qdisc_dev(sch);
585d763a	395
710fb396 AA	396	if (!opt) {
710fb396 AA	397	NL_SET_ERR_MSG(extack, "Missing CBS qdisc options which are mandatory");
585d763a	398	return -EINVAL;
710fb396	399	}
585d763a	400
990e35ec VCG	401	q->qdisc = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
	402	sch->handle, extack);
	403	if (!q->qdisc)
	404	return -ENOMEM;
	405
3e8b9bfa VCG	406	spin_lock(&cbs_list_lock);
	407	list_add(&q->cbs_list, &cbs_list);
	408	spin_unlock(&cbs_list_lock);
	409
990e35ec VCG	410	qdisc_hash_add(q->qdisc, false);
990e35ec VCG	411
3d0bd028 VCG	412	q->queue = sch->dev_queue - netdev_get_tx_queue(dev, 0);
	413
	414	q->enqueue = cbs_enqueue_soft;
	415	q->dequeue = cbs_dequeue_soft;
	416
585d763a VCG	417	qdisc_watchdog_init(&q->watchdog, sch);
585d763a VCG	418
3e8b9bfa	419	return cbs_change(sch, opt, extack);
585d763a VCG	420	}
	421
	422	static void cbs_destroy(struct Qdisc *sch)
	423	{
	424	struct cbs_sched_data *q = qdisc_priv(sch);
3d0bd028	425	struct net_device *dev = qdisc_dev(sch);
585d763a	426
3e8b9bfa VCG	427	/* Nothing to do if we couldn't create the underlying qdisc */
	428	if (!q->qdisc)
	429	return;
3d0bd028	430
e0a7683d	431	qdisc_watchdog_cancel(&q->watchdog);
3d0bd028	432	cbs_disable_offload(dev, q);
990e35ec	433
3e8b9bfa VCG	434	spin_lock(&cbs_list_lock);
	435	list_del(&q->cbs_list);
	436	spin_unlock(&cbs_list_lock);
	437
	438	qdisc_put(q->qdisc);
585d763a VCG	439	}
	440
	441	static int cbs_dump(struct Qdisc sch, struct sk_buff skb)
	442	{
	443	struct cbs_sched_data *q = qdisc_priv(sch);
	444	struct tc_cbs_qopt opt = { };
	445	struct nlattr *nest;
	446
ae0be8de	447	nest = nla_nest_start_noflag(skb, TCA_OPTIONS);
585d763a VCG	448	if (!nest)
	449	goto nla_put_failure;
	450
	451	opt.hicredit = q->hicredit;
	452	opt.locredit = q->locredit;
	453	opt.sendslope = div64_s64(q->sendslope, BYTES_PER_KBIT);
	454	opt.idleslope = div64_s64(q->idleslope, BYTES_PER_KBIT);
3d0bd028	455	opt.offload = q->offload;
585d763a VCG	456
	457	if (nla_put(skb, TCA_CBS_PARMS, sizeof(opt), &opt))
	458	goto nla_put_failure;
	459
	460	return nla_nest_end(skb, nest);
	461
	462	nla_put_failure:
	463	nla_nest_cancel(skb, nest);
	464	return -1;
	465	}
	466
990e35ec VCG	467	static int cbs_dump_class(struct Qdisc *sch, unsigned long cl,
	468	struct sk_buff skb, struct tcmsg tcm)
	469	{
	470	struct cbs_sched_data *q = qdisc_priv(sch);
	471
	472	if (cl != 1 \|\| !q->qdisc) /* only one class */
	473	return -ENOENT;
	474
	475	tcm->tcm_handle \|= TC_H_MIN(1);
	476	tcm->tcm_info = q->qdisc->handle;
	477
	478	return 0;
	479	}
	480
	481	static int cbs_graft(struct Qdisc sch, unsigned long arg, struct Qdisc new,
	482	struct Qdisc *old, struct netlink_ext_ack extack)
	483	{
	484	struct cbs_sched_data *q = qdisc_priv(sch);
	485
	486	if (!new) {
	487	new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
	488	sch->handle, NULL);
	489	if (!new)
	490	new = &noop_qdisc;
	491	}
	492
	493	*old = qdisc_replace(sch, new, &q->qdisc);
	494	return 0;
	495	}
	496
	497	static struct Qdisc cbs_leaf(struct Qdisc sch, unsigned long arg)
	498	{
	499	struct cbs_sched_data *q = qdisc_priv(sch);
	500
	501	return q->qdisc;
	502	}
	503
	504	static unsigned long cbs_find(struct Qdisc *sch, u32 classid)
	505	{
	506	return 1;
	507	}
	508
	509	static void cbs_walk(struct Qdisc sch, struct qdisc_walker walker)
	510	{
	511	if (!walker->stop) {
	512	if (walker->count >= walker->skip) {
	513	if (walker->fn(sch, 1, walker) < 0) {
	514	walker->stop = 1;
	515	return;
	516	}
	517	}
	518	walker->count++;
	519	}
	520	}
	521
	522	static const struct Qdisc_class_ops cbs_class_ops = {
	523	.graft = cbs_graft,
	524	.leaf = cbs_leaf,
	525	.find = cbs_find,
	526	.walk = cbs_walk,
	527	.dump = cbs_dump_class,
	528	};
	529
585d763a VCG	530	static struct Qdisc_ops cbs_qdisc_ops __read_mostly = {
585d763a VCG	531	.id = "cbs",
990e35ec	532	.cl_ops = &cbs_class_ops,
585d763a VCG	533	.priv_size = sizeof(struct cbs_sched_data),
	534	.enqueue = cbs_enqueue,
	535	.dequeue = cbs_dequeue,
	536	.peek = qdisc_peek_dequeued,
	537	.init = cbs_init,
	538	.reset = qdisc_reset_queue,
	539	.destroy = cbs_destroy,
	540	.change = cbs_change,
	541	.dump = cbs_dump,
	542	.owner = THIS_MODULE,
	543	};
	544
e0a7683d LD	545	static struct notifier_block cbs_device_notifier = {
	546	.notifier_call = cbs_dev_notifier,
	547	};
	548
585d763a VCG	549	static int __init cbs_module_init(void)
585d763a VCG	550	{
45d5cb13	551	int err;
e0a7683d	552
45d5cb13	553	err = register_netdevice_notifier(&cbs_device_notifier);
e0a7683d LD	554	if (err)
	555	return err;
	556
45d5cb13 Y	557	err = register_qdisc(&cbs_qdisc_ops);
	558	if (err)
	559	unregister_netdevice_notifier(&cbs_device_notifier);
	560
	561	return err;
585d763a VCG	562	}
	563
	564	static void __exit cbs_module_exit(void)
	565	{
	566	unregister_qdisc(&cbs_qdisc_ops);
e0a7683d	567	unregister_netdevice_notifier(&cbs_device_notifier);
585d763a VCG	568	}
	569	module_init(cbs_module_init)
	570	module_exit(cbs_module_exit)
	571	MODULE_LICENSE("GPL");