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-rw-r--r--net/sched/sch_choke.c517
1 files changed, 517 insertions, 0 deletions
diff --git a/net/sched/sch_choke.c b/net/sched/sch_choke.c
new file mode 100644
index 000000000..25d2daaa8
--- /dev/null
+++ b/net/sched/sch_choke.c
@@ -0,0 +1,517 @@
+// 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 other; /* Drops due to drop() calls */
+ 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,
+ .other = q->stats.other,
+ .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");
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