--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-only
+/* Flow Queue PIE discipline
+ *
+ * Copyright (C) 2019 Mohit P. Tahiliani <tahiliani@nitk.edu.in>
+ * Copyright (C) 2019 Sachin D. Patil <sdp.sachin@gmail.com>
+ * Copyright (C) 2019 V. Saicharan <vsaicharan1998@gmail.com>
+ * Copyright (C) 2019 Mohit Bhasi <mohitbhasi1998@gmail.com>
+ * Copyright (C) 2019 Leslie Monis <lesliemonis@gmail.com>
+ * Copyright (C) 2019 Gautam Ramakrishnan <gautamramk@gmail.com>
+ */
+
+#include <linux/jhash.h>
+#include <linux/sizes.h>
+#include <linux/vmalloc.h>
+#include <net/pkt_cls.h>
+#include <net/pie.h>
+
+/* Flow Queue PIE
+ *
+ * Principles:
+ * - Packets are classified on flows.
+ * - This is a Stochastic model (as we use a hash, several flows might
+ * be hashed to the same slot)
+ * - Each flow has a PIE managed queue.
+ * - Flows are linked onto two (Round Robin) lists,
+ * so that new flows have priority on old ones.
+ * - For a given flow, packets are not reordered.
+ * - Drops during enqueue only.
+ * - ECN capability is off by default.
+ * - ECN threshold (if ECN is enabled) is at 10% by default.
+ * - Uses timestamps to calculate queue delay by default.
+ */
+
+/**
+ * struct fq_pie_flow - contains data for each flow
+ * @vars: pie vars associated with the flow
+ * @deficit: number of remaining byte credits
+ * @backlog: size of data in the flow
+ * @qlen: number of packets in the flow
+ * @flowchain: flowchain for the flow
+ * @head: first packet in the flow
+ * @tail: last packet in the flow
+ */
+struct fq_pie_flow {
+ struct pie_vars vars;
+ s32 deficit;
+ u32 backlog;
+ u32 qlen;
+ struct list_head flowchain;
+ struct sk_buff *head;
+ struct sk_buff *tail;
+};
+
+struct fq_pie_sched_data {
+ struct tcf_proto __rcu *filter_list; /* optional external classifier */
+ struct tcf_block *block;
+ struct fq_pie_flow *flows;
+ struct Qdisc *sch;
+ struct list_head old_flows;
+ struct list_head new_flows;
+ struct pie_params p_params;
+ u32 ecn_prob;
+ u32 flows_cnt;
+ u32 quantum;
+ u32 memory_limit;
+ u32 new_flow_count;
+ u32 memory_usage;
+ u32 overmemory;
+ struct pie_stats stats;
+ struct timer_list adapt_timer;
+};
+
+static unsigned int fq_pie_hash(const struct fq_pie_sched_data *q,
+ struct sk_buff *skb)
+{
+ return reciprocal_scale(skb_get_hash(skb), q->flows_cnt);
+}
+
+static unsigned int fq_pie_classify(struct sk_buff *skb, struct Qdisc *sch,
+ int *qerr)
+{
+ struct fq_pie_sched_data *q = qdisc_priv(sch);
+ struct tcf_proto *filter;
+ struct tcf_result res;
+ int result;
+
+ if (TC_H_MAJ(skb->priority) == sch->handle &&
+ TC_H_MIN(skb->priority) > 0 &&
+ TC_H_MIN(skb->priority) <= q->flows_cnt)
+ return TC_H_MIN(skb->priority);
+
+ filter = rcu_dereference_bh(q->filter_list);
+ if (!filter)
+ return fq_pie_hash(q, skb) + 1;
+
+ *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
+ result = tcf_classify(skb, filter, &res, false);
+ if (result >= 0) {
+#ifdef CONFIG_NET_CLS_ACT
+ switch (result) {
+ case TC_ACT_STOLEN:
+ case TC_ACT_QUEUED:
+ case TC_ACT_TRAP:
+ *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
+ /* fall through */
+ case TC_ACT_SHOT:
+ return 0;
+ }
+#endif
+ if (TC_H_MIN(res.classid) <= q->flows_cnt)
+ return TC_H_MIN(res.classid);
+ }
+ return 0;
+}
+
+/* add skb to flow queue (tail add) */
+static inline void flow_queue_add(struct fq_pie_flow *flow,
+ struct sk_buff *skb)
+{
+ if (!flow->head)
+ flow->head = skb;
+ else
+ flow->tail->next = skb;
+ flow->tail = skb;
+ skb->next = NULL;
+}
+
+static int fq_pie_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch,
+ struct sk_buff **to_free)
+{
+ struct fq_pie_sched_data *q = qdisc_priv(sch);
+ struct fq_pie_flow *sel_flow;
+ int uninitialized_var(ret);
+ u8 memory_limited = false;
+ u8 enqueue = false;
+ u32 pkt_len;
+ u32 idx;
+
+ /* Classifies packet into corresponding flow */
+ idx = fq_pie_classify(skb, sch, &ret);
+ sel_flow = &q->flows[idx];
+
+ /* Checks whether adding a new packet would exceed memory limit */
+ get_pie_cb(skb)->mem_usage = skb->truesize;
+ memory_limited = q->memory_usage > q->memory_limit + skb->truesize;
+
+ /* Checks if the qdisc is full */
+ if (unlikely(qdisc_qlen(sch) >= sch->limit)) {
+ q->stats.overlimit++;
+ goto out;
+ } else if (unlikely(memory_limited)) {
+ q->overmemory++;
+ }
+
+ if (!pie_drop_early(sch, &q->p_params, &sel_flow->vars,
+ sel_flow->backlog, skb->len)) {
+ enqueue = true;
+ } else if (q->p_params.ecn &&
+ sel_flow->vars.prob <= (MAX_PROB / 100) * q->ecn_prob &&
+ INET_ECN_set_ce(skb)) {
+ /* If packet is ecn capable, mark it if drop probability
+ * is lower than the parameter ecn_prob, else drop it.
+ */
+ q->stats.ecn_mark++;
+ enqueue = true;
+ }
+ if (enqueue) {
+ /* Set enqueue time only when dq_rate_estimator is disabled. */
+ if (!q->p_params.dq_rate_estimator)
+ pie_set_enqueue_time(skb);
+
+ pkt_len = qdisc_pkt_len(skb);
+ q->stats.packets_in++;
+ q->memory_usage += skb->truesize;
+ sch->qstats.backlog += pkt_len;
+ sch->q.qlen++;
+ flow_queue_add(sel_flow, skb);
+ if (list_empty(&sel_flow->flowchain)) {
+ list_add_tail(&sel_flow->flowchain, &q->new_flows);
+ q->new_flow_count++;
+ sel_flow->deficit = q->quantum;
+ sel_flow->qlen = 0;
+ sel_flow->backlog = 0;
+ }
+ sel_flow->qlen++;
+ sel_flow->backlog += pkt_len;
+ return NET_XMIT_SUCCESS;
+ }
+out:
+ q->stats.dropped++;
+ sel_flow->vars.accu_prob = 0;
+ sel_flow->vars.accu_prob_overflows = 0;
+ __qdisc_drop(skb, to_free);
+ qdisc_qstats_drop(sch);
+ return NET_XMIT_CN;
+}
+
+static const struct nla_policy fq_pie_policy[TCA_FQ_PIE_MAX + 1] = {
+ [TCA_FQ_PIE_LIMIT] = {.type = NLA_U32},
+ [TCA_FQ_PIE_FLOWS] = {.type = NLA_U32},
+ [TCA_FQ_PIE_TARGET] = {.type = NLA_U32},
+ [TCA_FQ_PIE_TUPDATE] = {.type = NLA_U32},
+ [TCA_FQ_PIE_ALPHA] = {.type = NLA_U32},
+ [TCA_FQ_PIE_BETA] = {.type = NLA_U32},
+ [TCA_FQ_PIE_QUANTUM] = {.type = NLA_U32},
+ [TCA_FQ_PIE_MEMORY_LIMIT] = {.type = NLA_U32},
+ [TCA_FQ_PIE_ECN_PROB] = {.type = NLA_U32},
+ [TCA_FQ_PIE_ECN] = {.type = NLA_U32},
+ [TCA_FQ_PIE_BYTEMODE] = {.type = NLA_U32},
+ [TCA_FQ_PIE_DQ_RATE_ESTIMATOR] = {.type = NLA_U32},
+};
+
+static inline struct sk_buff *dequeue_head(struct fq_pie_flow *flow)
+{
+ struct sk_buff *skb = flow->head;
+
+ flow->head = skb->next;
+ skb->next = NULL;
+ return skb;
+}
+
+static struct sk_buff *fq_pie_qdisc_dequeue(struct Qdisc *sch)
+{
+ struct fq_pie_sched_data *q = qdisc_priv(sch);
+ struct sk_buff *skb = NULL;
+ struct fq_pie_flow *flow;
+ struct list_head *head;
+ u32 pkt_len;
+
+begin:
+ head = &q->new_flows;
+ if (list_empty(head)) {
+ head = &q->old_flows;
+ if (list_empty(head))
+ return NULL;
+ }
+
+ flow = list_first_entry(head, struct fq_pie_flow, flowchain);
+ /* Flow has exhausted all its credits */
+ if (flow->deficit <= 0) {
+ flow->deficit += q->quantum;
+ list_move_tail(&flow->flowchain, &q->old_flows);
+ goto begin;
+ }
+
+ if (flow->head) {
+ skb = dequeue_head(flow);
+ pkt_len = qdisc_pkt_len(skb);
+ sch->qstats.backlog -= pkt_len;
+ sch->q.qlen--;
+ qdisc_bstats_update(sch, skb);
+ }
+
+ if (!skb) {
+ /* force a pass through old_flows to prevent starvation */
+ if (head == &q->new_flows && !list_empty(&q->old_flows))
+ list_move_tail(&flow->flowchain, &q->old_flows);
+ else
+ list_del_init(&flow->flowchain);
+ goto begin;
+ }
+
+ flow->qlen--;
+ flow->deficit -= pkt_len;
+ flow->backlog -= pkt_len;
+ q->memory_usage -= get_pie_cb(skb)->mem_usage;
+ pie_process_dequeue(skb, &q->p_params, &flow->vars, flow->backlog);
+ return skb;
+}
+
+static int fq_pie_change(struct Qdisc *sch, struct nlattr *opt,
+ struct netlink_ext_ack *extack)
+{
+ struct fq_pie_sched_data *q = qdisc_priv(sch);
+ struct nlattr *tb[TCA_FQ_PIE_MAX + 1];
+ unsigned int len_dropped = 0;
+ unsigned int num_dropped = 0;
+ int err;
+
+ if (!opt)
+ return -EINVAL;
+
+ err = nla_parse_nested(tb, TCA_FQ_PIE_MAX, opt, fq_pie_policy, extack);
+ if (err < 0)
+ return err;
+
+ sch_tree_lock(sch);
+ if (tb[TCA_FQ_PIE_LIMIT]) {
+ u32 limit = nla_get_u32(tb[TCA_FQ_PIE_LIMIT]);
+
+ q->p_params.limit = limit;
+ sch->limit = limit;
+ }
+ if (tb[TCA_FQ_PIE_FLOWS]) {
+ if (q->flows) {
+ NL_SET_ERR_MSG_MOD(extack,
+ "Number of flows cannot be changed");
+ goto flow_error;
+ }
+ q->flows_cnt = nla_get_u32(tb[TCA_FQ_PIE_FLOWS]);
+ if (!q->flows_cnt || q->flows_cnt > 65536) {
+ NL_SET_ERR_MSG_MOD(extack,
+ "Number of flows must be < 65536");
+ goto flow_error;
+ }
+ }
+
+ /* convert from microseconds to pschedtime */
+ if (tb[TCA_FQ_PIE_TARGET]) {
+ /* target is in us */
+ u32 target = nla_get_u32(tb[TCA_FQ_PIE_TARGET]);
+
+ /* convert to pschedtime */
+ q->p_params.target =
+ PSCHED_NS2TICKS((u64)target * NSEC_PER_USEC);
+ }
+
+ /* tupdate is in jiffies */
+ if (tb[TCA_FQ_PIE_TUPDATE])
+ q->p_params.tupdate =
+ usecs_to_jiffies(nla_get_u32(tb[TCA_FQ_PIE_TUPDATE]));
+
+ if (tb[TCA_FQ_PIE_ALPHA])
+ q->p_params.alpha = nla_get_u32(tb[TCA_FQ_PIE_ALPHA]);
+
+ if (tb[TCA_FQ_PIE_BETA])
+ q->p_params.beta = nla_get_u32(tb[TCA_FQ_PIE_BETA]);
+
+ if (tb[TCA_FQ_PIE_QUANTUM])
+ q->quantum = nla_get_u32(tb[TCA_FQ_PIE_QUANTUM]);
+
+ if (tb[TCA_FQ_PIE_MEMORY_LIMIT])
+ q->memory_limit = nla_get_u32(tb[TCA_FQ_PIE_MEMORY_LIMIT]);
+
+ if (tb[TCA_FQ_PIE_ECN_PROB])
+ q->ecn_prob = nla_get_u32(tb[TCA_FQ_PIE_ECN_PROB]);
+
+ if (tb[TCA_FQ_PIE_ECN])
+ q->p_params.ecn = nla_get_u32(tb[TCA_FQ_PIE_ECN]);
+
+ if (tb[TCA_FQ_PIE_BYTEMODE])
+ q->p_params.bytemode = nla_get_u32(tb[TCA_FQ_PIE_BYTEMODE]);
+
+ if (tb[TCA_FQ_PIE_DQ_RATE_ESTIMATOR])
+ q->p_params.dq_rate_estimator =
+ nla_get_u32(tb[TCA_FQ_PIE_DQ_RATE_ESTIMATOR]);
+
+ /* Drop excess packets if new limit is lower */
+ while (sch->q.qlen > sch->limit) {
+ struct sk_buff *skb = fq_pie_qdisc_dequeue(sch);
+
+ kfree_skb(skb);
+ len_dropped += qdisc_pkt_len(skb);
+ num_dropped += 1;
+ }
+ qdisc_tree_reduce_backlog(sch, num_dropped, len_dropped);
+
+ sch_tree_unlock(sch);
+ return 0;
+
+flow_error:
+ sch_tree_unlock(sch);
+ return -EINVAL;
+}
+
+static void fq_pie_timer(struct timer_list *t)
+{
+ struct fq_pie_sched_data *q = from_timer(q, t, adapt_timer);
+ struct Qdisc *sch = q->sch;
+ spinlock_t *root_lock; /* to lock qdisc for probability calculations */
+ u16 idx;
+
+ root_lock = qdisc_lock(qdisc_root_sleeping(sch));
+ spin_lock(root_lock);
+
+ for (idx = 0; idx < q->flows_cnt; idx++)
+ pie_calculate_probability(&q->p_params, &q->flows[idx].vars,
+ q->flows[idx].backlog);
+
+ /* reset the timer to fire after 'tupdate' jiffies. */
+ if (q->p_params.tupdate)
+ mod_timer(&q->adapt_timer, jiffies + q->p_params.tupdate);
+
+ spin_unlock(root_lock);
+}
+
+static int fq_pie_init(struct Qdisc *sch, struct nlattr *opt,
+ struct netlink_ext_ack *extack)
+{
+ struct fq_pie_sched_data *q = qdisc_priv(sch);
+ int err;
+ u16 idx;
+
+ pie_params_init(&q->p_params);
+ sch->limit = 10 * 1024;
+ q->p_params.limit = sch->limit;
+ q->quantum = psched_mtu(qdisc_dev(sch));
+ q->sch = sch;
+ q->ecn_prob = 10;
+ q->flows_cnt = 1024;
+ q->memory_limit = SZ_32M;
+
+ INIT_LIST_HEAD(&q->new_flows);
+ INIT_LIST_HEAD(&q->old_flows);
+
+ if (opt) {
+ err = fq_pie_change(sch, opt, extack);
+
+ if (err)
+ return err;
+ }
+
+ err = tcf_block_get(&q->block, &q->filter_list, sch, extack);
+ if (err)
+ goto init_failure;
+
+ q->flows = kvcalloc(q->flows_cnt, sizeof(struct fq_pie_flow),
+ GFP_KERNEL);
+ if (!q->flows) {
+ err = -ENOMEM;
+ goto init_failure;
+ }
+ for (idx = 0; idx < q->flows_cnt; idx++) {
+ struct fq_pie_flow *flow = q->flows + idx;
+
+ INIT_LIST_HEAD(&flow->flowchain);
+ pie_vars_init(&flow->vars);
+ }
+
+ timer_setup(&q->adapt_timer, fq_pie_timer, 0);
+ mod_timer(&q->adapt_timer, jiffies + HZ / 2);
+
+ return 0;
+
+init_failure:
+ q->flows_cnt = 0;
+
+ return err;
+}
+
+static int fq_pie_dump(struct Qdisc *sch, struct sk_buff *skb)
+{
+ struct fq_pie_sched_data *q = qdisc_priv(sch);
+ struct nlattr *opts;
+
+ opts = nla_nest_start(skb, TCA_OPTIONS);
+ if (!opts)
+ return -EMSGSIZE;
+
+ /* convert target from pschedtime to us */
+ if (nla_put_u32(skb, TCA_FQ_PIE_LIMIT, sch->limit) ||
+ nla_put_u32(skb, TCA_FQ_PIE_FLOWS, q->flows_cnt) ||
+ nla_put_u32(skb, TCA_FQ_PIE_TARGET,
+ ((u32)PSCHED_TICKS2NS(q->p_params.target)) /
+ NSEC_PER_USEC) ||
+ nla_put_u32(skb, TCA_FQ_PIE_TUPDATE,
+ jiffies_to_usecs(q->p_params.tupdate)) ||
+ nla_put_u32(skb, TCA_FQ_PIE_ALPHA, q->p_params.alpha) ||
+ nla_put_u32(skb, TCA_FQ_PIE_BETA, q->p_params.beta) ||
+ nla_put_u32(skb, TCA_FQ_PIE_QUANTUM, q->quantum) ||
+ nla_put_u32(skb, TCA_FQ_PIE_MEMORY_LIMIT, q->memory_limit) ||
+ nla_put_u32(skb, TCA_FQ_PIE_ECN_PROB, q->ecn_prob) ||
+ nla_put_u32(skb, TCA_FQ_PIE_ECN, q->p_params.ecn) ||
+ nla_put_u32(skb, TCA_FQ_PIE_BYTEMODE, q->p_params.bytemode) ||
+ nla_put_u32(skb, TCA_FQ_PIE_DQ_RATE_ESTIMATOR,
+ q->p_params.dq_rate_estimator))
+ goto nla_put_failure;
+
+ return nla_nest_end(skb, opts);
+
+nla_put_failure:
+ nla_nest_cancel(skb, opts);
+ return -EMSGSIZE;
+}
+
+static int fq_pie_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
+{
+ struct fq_pie_sched_data *q = qdisc_priv(sch);
+ struct tc_fq_pie_xstats st = {
+ .packets_in = q->stats.packets_in,
+ .overlimit = q->stats.overlimit,
+ .overmemory = q->overmemory,
+ .dropped = q->stats.dropped,
+ .ecn_mark = q->stats.ecn_mark,
+ .new_flow_count = q->new_flow_count,
+ .memory_usage = q->memory_usage,
+ };
+ struct list_head *pos;
+
+ sch_tree_lock(sch);
+ list_for_each(pos, &q->new_flows)
+ st.new_flows_len++;
+
+ list_for_each(pos, &q->old_flows)
+ st.old_flows_len++;
+ sch_tree_unlock(sch);
+
+ return gnet_stats_copy_app(d, &st, sizeof(st));
+}
+
+static void fq_pie_reset(struct Qdisc *sch)
+{
+ struct fq_pie_sched_data *q = qdisc_priv(sch);
+ u16 idx;
+
+ INIT_LIST_HEAD(&q->new_flows);
+ INIT_LIST_HEAD(&q->old_flows);
+ for (idx = 0; idx < q->flows_cnt; idx++) {
+ struct fq_pie_flow *flow = q->flows + idx;
+
+ /* Removes all packets from flow */
+ rtnl_kfree_skbs(flow->head, flow->tail);
+ flow->head = NULL;
+
+ INIT_LIST_HEAD(&flow->flowchain);
+ pie_vars_init(&flow->vars);
+ }
+
+ sch->q.qlen = 0;
+ sch->qstats.backlog = 0;
+}
+
+static void fq_pie_destroy(struct Qdisc *sch)
+{
+ struct fq_pie_sched_data *q = qdisc_priv(sch);
+
+ tcf_block_put(q->block);
+ del_timer_sync(&q->adapt_timer);
+ kvfree(q->flows);
+}
+
+static struct Qdisc_ops fq_pie_qdisc_ops __read_mostly = {
+ .id = "fq_pie",
+ .priv_size = sizeof(struct fq_pie_sched_data),
+ .enqueue = fq_pie_qdisc_enqueue,
+ .dequeue = fq_pie_qdisc_dequeue,
+ .peek = qdisc_peek_dequeued,
+ .init = fq_pie_init,
+ .destroy = fq_pie_destroy,
+ .reset = fq_pie_reset,
+ .change = fq_pie_change,
+ .dump = fq_pie_dump,
+ .dump_stats = fq_pie_dump_stats,
+ .owner = THIS_MODULE,
+};
+
+static int __init fq_pie_module_init(void)
+{
+ return register_qdisc(&fq_pie_qdisc_ops);
+}
+
+static void __exit fq_pie_module_exit(void)
+{
+ unregister_qdisc(&fq_pie_qdisc_ops);
+}
+
+module_init(fq_pie_module_init);
+module_exit(fq_pie_module_exit);
+
+MODULE_DESCRIPTION("Flow Queue Proportional Integral controller Enhanced (FQ-PIE)");
+MODULE_AUTHOR("Mohit P. Tahiliani");
+MODULE_LICENSE("GPL");
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