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-rw-r--r--net/sched/sch_cbs.c576
1 files changed, 576 insertions, 0 deletions
diff --git a/net/sched/sch_cbs.c b/net/sched/sch_cbs.c
new file mode 100644
index 0000000000..cac870eb78
--- /dev/null
+++ b/net/sched/sch_cbs.c
@@ -0,0 +1,576 @@
+// 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/ethtool.h>
+#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;
+
+ /* The previous packet is still being sent */
+ if (now < q->last) {
+ qdisc_watchdog_schedule_ns(&q->watchdog, q->last);
+ return NULL;
+ }
+ 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);
+ /* Estimate of the transmission of the last byte of the packet in ns */
+ if (unlikely(atomic64_read(&q->port_rate) == 0))
+ q->last = now;
+ else
+ q->last = now + div64_s64(len * NSEC_PER_SEC,
+ atomic64_read(&q->port_rate));
+
+ 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) {
+ tc_qdisc_stats_dump(sch, 1, walker);
+ }
+}
+
+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");
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-04 23:59:38 +0000