1 files changed, 515 insertions, 0 deletions

diff --git a/net/sched/sch_choke.c b/net/sched/sch_choke.c
new file mode 100644
index 000000000..3ac3e5c80
--- /dev/null
+++ b/net/sched/sch_choke.c
@@ -0,0 +1,515 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * net/sched/sch_choke.c	CHOKE scheduler
+ *
+ * Copyright (c) 2011 Stephen Hemminger <shemminger@vyatta.com>
+ * Copyright (c) 2011 Eric Dumazet <eric.dumazet@gmail.com>
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/skbuff.h>
+#include <linux/vmalloc.h>
+#include <net/pkt_sched.h>
+#include <net/pkt_cls.h>
+#include <net/inet_ecn.h>
+#include <net/red.h>
+#include <net/flow_dissector.h>
+
+/*
+   CHOKe stateless AQM for fair bandwidth allocation
+   =================================================
+
+   CHOKe (CHOose and Keep for responsive flows, CHOose and Kill for
+   unresponsive flows) is a variant of RED that penalizes misbehaving flows but
+   maintains no flow state. The difference from RED is an additional step
+   during the enqueuing process. If average queue size is over the
+   low threshold (qmin), a packet is chosen at random from the queue.
+   If both the new and chosen packet are from the same flow, both
+   are dropped. Unlike RED, CHOKe is not really a "classful" qdisc because it
+   needs to access packets in queue randomly. It has a minimal class
+   interface to allow overriding the builtin flow classifier with
+   filters.
+
+   Source:
+   R. Pan, B. Prabhakar, and K. Psounis, "CHOKe, A Stateless
+   Active Queue Management Scheme for Approximating Fair Bandwidth Allocation",
+   IEEE INFOCOM, 2000.
+
+   A. Tang, J. Wang, S. Low, "Understanding CHOKe: Throughput and Spatial
+   Characteristics", IEEE/ACM Transactions on Networking, 2004
+
+ */
+
+/* Upper bound on size of sk_buff table (packets) */
+#define CHOKE_MAX_QUEUE	(128*1024 - 1)
+
+struct choke_sched_data {
+/* Parameters */
+	u32		 limit;
+	unsigned char	 flags;
+
+	struct red_parms parms;
+
+/* Variables */
+	struct red_vars  vars;
+	struct {
+		u32	prob_drop;	/* Early probability drops */
+		u32	prob_mark;	/* Early probability marks */
+		u32	forced_drop;	/* Forced drops, qavg > max_thresh */
+		u32	forced_mark;	/* Forced marks, qavg > max_thresh */
+		u32	pdrop;          /* Drops due to queue limits */
+		u32	matched;	/* Drops to flow match */
+	} stats;
+
+	unsigned int	 head;
+	unsigned int	 tail;
+
+	unsigned int	 tab_mask; /* size - 1 */
+
+	struct sk_buff **tab;
+};
+
+/* number of elements in queue including holes */
+static unsigned int choke_len(const struct choke_sched_data *q)
+{
+	return (q->tail - q->head) & q->tab_mask;
+}
+
+/* Is ECN parameter configured */
+static int use_ecn(const struct choke_sched_data *q)
+{
+	return q->flags & TC_RED_ECN;
+}
+
+/* Should packets over max just be dropped (versus marked) */
+static int use_harddrop(const struct choke_sched_data *q)
+{
+	return q->flags & TC_RED_HARDDROP;
+}
+
+/* Move head pointer forward to skip over holes */
+static void choke_zap_head_holes(struct choke_sched_data *q)
+{
+	do {
+		q->head = (q->head + 1) & q->tab_mask;
+		if (q->head == q->tail)
+			break;
+	} while (q->tab[q->head] == NULL);
+}
+
+/* Move tail pointer backwards to reuse holes */
+static void choke_zap_tail_holes(struct choke_sched_data *q)
+{
+	do {
+		q->tail = (q->tail - 1) & q->tab_mask;
+		if (q->head == q->tail)
+			break;
+	} while (q->tab[q->tail] == NULL);
+}
+
+/* Drop packet from queue array by creating a "hole" */
+static void choke_drop_by_idx(struct Qdisc *sch, unsigned int idx,
+			      struct sk_buff **to_free)
+{
+	struct choke_sched_data *q = qdisc_priv(sch);
+	struct sk_buff *skb = q->tab[idx];
+
+	q->tab[idx] = NULL;
+
+	if (idx == q->head)
+		choke_zap_head_holes(q);
+	if (idx == q->tail)
+		choke_zap_tail_holes(q);
+
+	qdisc_qstats_backlog_dec(sch, skb);
+	qdisc_tree_reduce_backlog(sch, 1, qdisc_pkt_len(skb));
+	qdisc_drop(skb, sch, to_free);
+	--sch->q.qlen;
+}
+
+struct choke_skb_cb {
+	u8			keys_valid;
+	struct			flow_keys_digest keys;
+};
+
+static inline struct choke_skb_cb *choke_skb_cb(const struct sk_buff *skb)
+{
+	qdisc_cb_private_validate(skb, sizeof(struct choke_skb_cb));
+	return (struct choke_skb_cb *)qdisc_skb_cb(skb)->data;
+}
+
+/*
+ * Compare flow of two packets
+ *  Returns true only if source and destination address and port match.
+ *          false for special cases
+ */
+static bool choke_match_flow(struct sk_buff *skb1,
+			     struct sk_buff *skb2)
+{
+	struct flow_keys temp;
+
+	if (skb1->protocol != skb2->protocol)
+		return false;
+
+	if (!choke_skb_cb(skb1)->keys_valid) {
+		choke_skb_cb(skb1)->keys_valid = 1;
+		skb_flow_dissect_flow_keys(skb1, &temp, 0);
+		make_flow_keys_digest(&choke_skb_cb(skb1)->keys, &temp);
+	}
+
+	if (!choke_skb_cb(skb2)->keys_valid) {
+		choke_skb_cb(skb2)->keys_valid = 1;
+		skb_flow_dissect_flow_keys(skb2, &temp, 0);
+		make_flow_keys_digest(&choke_skb_cb(skb2)->keys, &temp);
+	}
+
+	return !memcmp(&choke_skb_cb(skb1)->keys,
+		       &choke_skb_cb(skb2)->keys,
+		       sizeof(choke_skb_cb(skb1)->keys));
+}
+
+/*
+ * Select a packet at random from queue
+ * HACK: since queue can have holes from previous deletion; retry several
+ *   times to find a random skb but then just give up and return the head
+ * Will return NULL if queue is empty (q->head == q->tail)
+ */
+static struct sk_buff *choke_peek_random(const struct choke_sched_data *q,
+					 unsigned int *pidx)
+{
+	struct sk_buff *skb;
+	int retrys = 3;
+
+	do {
+		*pidx = (q->head + prandom_u32_max(choke_len(q))) & q->tab_mask;
+		skb = q->tab[*pidx];
+		if (skb)
+			return skb;
+	} while (--retrys > 0);
+
+	return q->tab[*pidx = q->head];
+}
+
+/*
+ * Compare new packet with random packet in queue
+ * returns true if matched and sets *pidx
+ */
+static bool choke_match_random(const struct choke_sched_data *q,
+			       struct sk_buff *nskb,
+			       unsigned int *pidx)
+{
+	struct sk_buff *oskb;
+
+	if (q->head == q->tail)
+		return false;
+
+	oskb = choke_peek_random(q, pidx);
+	return choke_match_flow(oskb, nskb);
+}
+
+static int choke_enqueue(struct sk_buff *skb, struct Qdisc *sch,
+			 struct sk_buff **to_free)
+{
+	struct choke_sched_data *q = qdisc_priv(sch);
+	const struct red_parms *p = &q->parms;
+
+	choke_skb_cb(skb)->keys_valid = 0;
+	/* Compute average queue usage (see RED) */
+	q->vars.qavg = red_calc_qavg(p, &q->vars, sch->q.qlen);
+	if (red_is_idling(&q->vars))
+		red_end_of_idle_period(&q->vars);
+
+	/* Is queue small? */
+	if (q->vars.qavg <= p->qth_min)
+		q->vars.qcount = -1;
+	else {
+		unsigned int idx;
+
+		/* Draw a packet at random from queue and compare flow */
+		if (choke_match_random(q, skb, &idx)) {
+			q->stats.matched++;
+			choke_drop_by_idx(sch, idx, to_free);
+			goto congestion_drop;
+		}
+
+		/* Queue is large, always mark/drop */
+		if (q->vars.qavg > p->qth_max) {
+			q->vars.qcount = -1;
+
+			qdisc_qstats_overlimit(sch);
+			if (use_harddrop(q) || !use_ecn(q) ||
+			    !INET_ECN_set_ce(skb)) {
+				q->stats.forced_drop++;
+				goto congestion_drop;
+			}
+
+			q->stats.forced_mark++;
+		} else if (++q->vars.qcount) {
+			if (red_mark_probability(p, &q->vars, q->vars.qavg)) {
+				q->vars.qcount = 0;
+				q->vars.qR = red_random(p);
+
+				qdisc_qstats_overlimit(sch);
+				if (!use_ecn(q) || !INET_ECN_set_ce(skb)) {
+					q->stats.prob_drop++;
+					goto congestion_drop;
+				}
+
+				q->stats.prob_mark++;
+			}
+		} else
+			q->vars.qR = red_random(p);
+	}
+
+	/* Admit new packet */
+	if (sch->q.qlen < q->limit) {
+		q->tab[q->tail] = skb;
+		q->tail = (q->tail + 1) & q->tab_mask;
+		++sch->q.qlen;
+		qdisc_qstats_backlog_inc(sch, skb);
+		return NET_XMIT_SUCCESS;
+	}
+
+	q->stats.pdrop++;
+	return qdisc_drop(skb, sch, to_free);
+
+congestion_drop:
+	qdisc_drop(skb, sch, to_free);
+	return NET_XMIT_CN;
+}
+
+static struct sk_buff *choke_dequeue(struct Qdisc *sch)
+{
+	struct choke_sched_data *q = qdisc_priv(sch);
+	struct sk_buff *skb;
+
+	if (q->head == q->tail) {
+		if (!red_is_idling(&q->vars))
+			red_start_of_idle_period(&q->vars);
+		return NULL;
+	}
+
+	skb = q->tab[q->head];
+	q->tab[q->head] = NULL;
+	choke_zap_head_holes(q);
+	--sch->q.qlen;
+	qdisc_qstats_backlog_dec(sch, skb);
+	qdisc_bstats_update(sch, skb);
+
+	return skb;
+}
+
+static void choke_reset(struct Qdisc *sch)
+{
+	struct choke_sched_data *q = qdisc_priv(sch);
+
+	while (q->head != q->tail) {
+		struct sk_buff *skb = q->tab[q->head];
+
+		q->head = (q->head + 1) & q->tab_mask;
+		if (!skb)
+			continue;
+		rtnl_qdisc_drop(skb, sch);
+	}
+
+	if (q->tab)
+		memset(q->tab, 0, (q->tab_mask + 1) * sizeof(struct sk_buff *));
+	q->head = q->tail = 0;
+	red_restart(&q->vars);
+}
+
+static const struct nla_policy choke_policy[TCA_CHOKE_MAX + 1] = {
+	[TCA_CHOKE_PARMS]	= { .len = sizeof(struct tc_red_qopt) },
+	[TCA_CHOKE_STAB]	= { .len = RED_STAB_SIZE },
+	[TCA_CHOKE_MAX_P]	= { .type = NLA_U32 },
+};
+
+
+static void choke_free(void *addr)
+{
+	kvfree(addr);
+}
+
+static int choke_change(struct Qdisc *sch, struct nlattr *opt,
+			struct netlink_ext_ack *extack)
+{
+	struct choke_sched_data *q = qdisc_priv(sch);
+	struct nlattr *tb[TCA_CHOKE_MAX + 1];
+	const struct tc_red_qopt *ctl;
+	int err;
+	struct sk_buff **old = NULL;
+	unsigned int mask;
+	u32 max_P;
+	u8 *stab;
+
+	if (opt == NULL)
+		return -EINVAL;
+
+	err = nla_parse_nested_deprecated(tb, TCA_CHOKE_MAX, opt,
+					  choke_policy, NULL);
+	if (err < 0)
+		return err;
+
+	if (tb[TCA_CHOKE_PARMS] == NULL ||
+	    tb[TCA_CHOKE_STAB] == NULL)
+		return -EINVAL;
+
+	max_P = tb[TCA_CHOKE_MAX_P] ? nla_get_u32(tb[TCA_CHOKE_MAX_P]) : 0;
+
+	ctl = nla_data(tb[TCA_CHOKE_PARMS]);
+	stab = nla_data(tb[TCA_CHOKE_STAB]);
+	if (!red_check_params(ctl->qth_min, ctl->qth_max, ctl->Wlog, ctl->Scell_log, stab))
+		return -EINVAL;
+
+	if (ctl->limit > CHOKE_MAX_QUEUE)
+		return -EINVAL;
+
+	mask = roundup_pow_of_two(ctl->limit + 1) - 1;
+	if (mask != q->tab_mask) {
+		struct sk_buff **ntab;
+
+		ntab = kvcalloc(mask + 1, sizeof(struct sk_buff *), GFP_KERNEL);
+		if (!ntab)
+			return -ENOMEM;
+
+		sch_tree_lock(sch);
+		old = q->tab;
+		if (old) {
+			unsigned int oqlen = sch->q.qlen, tail = 0;
+			unsigned dropped = 0;
+
+			while (q->head != q->tail) {
+				struct sk_buff *skb = q->tab[q->head];
+
+				q->head = (q->head + 1) & q->tab_mask;
+				if (!skb)
+					continue;
+				if (tail < mask) {
+					ntab[tail++] = skb;
+					continue;
+				}
+				dropped += qdisc_pkt_len(skb);
+				qdisc_qstats_backlog_dec(sch, skb);
+				--sch->q.qlen;
+				rtnl_qdisc_drop(skb, sch);
+			}
+			qdisc_tree_reduce_backlog(sch, oqlen - sch->q.qlen, dropped);
+			q->head = 0;
+			q->tail = tail;
+		}
+
+		q->tab_mask = mask;
+		q->tab = ntab;
+	} else
+		sch_tree_lock(sch);
+
+	q->flags = ctl->flags;
+	q->limit = ctl->limit;
+
+	red_set_parms(&q->parms, ctl->qth_min, ctl->qth_max, ctl->Wlog,
+		      ctl->Plog, ctl->Scell_log,
+		      stab,
+		      max_P);
+	red_set_vars(&q->vars);
+
+	if (q->head == q->tail)
+		red_end_of_idle_period(&q->vars);
+
+	sch_tree_unlock(sch);
+	choke_free(old);
+	return 0;
+}
+
+static int choke_init(struct Qdisc *sch, struct nlattr *opt,
+		      struct netlink_ext_ack *extack)
+{
+	return choke_change(sch, opt, extack);
+}
+
+static int choke_dump(struct Qdisc *sch, struct sk_buff *skb)
+{
+	struct choke_sched_data *q = qdisc_priv(sch);
+	struct nlattr *opts = NULL;
+	struct tc_red_qopt opt = {
+		.limit		= q->limit,
+		.flags		= q->flags,
+		.qth_min	= q->parms.qth_min >> q->parms.Wlog,
+		.qth_max	= q->parms.qth_max >> q->parms.Wlog,
+		.Wlog		= q->parms.Wlog,
+		.Plog		= q->parms.Plog,
+		.Scell_log	= q->parms.Scell_log,
+	};
+
+	opts = nla_nest_start_noflag(skb, TCA_OPTIONS);
+	if (opts == NULL)
+		goto nla_put_failure;
+
+	if (nla_put(skb, TCA_CHOKE_PARMS, sizeof(opt), &opt) ||
+	    nla_put_u32(skb, TCA_CHOKE_MAX_P, q->parms.max_P))
+		goto nla_put_failure;
+	return nla_nest_end(skb, opts);
+
+nla_put_failure:
+	nla_nest_cancel(skb, opts);
+	return -EMSGSIZE;
+}
+
+static int choke_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
+{
+	struct choke_sched_data *q = qdisc_priv(sch);
+	struct tc_choke_xstats st = {
+		.early	= q->stats.prob_drop + q->stats.forced_drop,
+		.marked	= q->stats.prob_mark + q->stats.forced_mark,
+		.pdrop	= q->stats.pdrop,
+		.matched = q->stats.matched,
+	};
+
+	return gnet_stats_copy_app(d, &st, sizeof(st));
+}
+
+static void choke_destroy(struct Qdisc *sch)
+{
+	struct choke_sched_data *q = qdisc_priv(sch);
+
+	choke_free(q->tab);
+}
+
+static struct sk_buff *choke_peek_head(struct Qdisc *sch)
+{
+	struct choke_sched_data *q = qdisc_priv(sch);
+
+	return (q->head != q->tail) ? q->tab[q->head] : NULL;
+}
+
+static struct Qdisc_ops choke_qdisc_ops __read_mostly = {
+	.id		=	"choke",
+	.priv_size	=	sizeof(struct choke_sched_data),
+
+	.enqueue	=	choke_enqueue,
+	.dequeue	=	choke_dequeue,
+	.peek		=	choke_peek_head,
+	.init		=	choke_init,
+	.destroy	=	choke_destroy,
+	.reset		=	choke_reset,
+	.change		=	choke_change,
+	.dump		=	choke_dump,
+	.dump_stats	=	choke_dump_stats,
+	.owner		=	THIS_MODULE,
+};
+
+static int __init choke_module_init(void)
+{
+	return register_qdisc(&choke_qdisc_ops);
+}
+
+static void __exit choke_module_exit(void)
+{
+	unregister_qdisc(&choke_qdisc_ops);
+}
+
+module_init(choke_module_init)
+module_exit(choke_module_exit)
+
+MODULE_LICENSE("GPL");