net/sched/sch_fq_codel.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Fair Queue CoDel discipline
   4  *
   5  *  Copyright (C) 2012,2015 Eric Dumazet <edumazet@google.com>
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/types.h>
  10 #include <linux/kernel.h>
  11 #include <linux/jiffies.h>
  12 #include <linux/string.h>
  13 #include <linux/in.h>
  14 #include <linux/errno.h>
  15 #include <linux/init.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/jhash.h>
  18 #include <linux/slab.h>
  19 #include <linux/vmalloc.h>
  20 #include <net/netlink.h>
  21 #include <net/pkt_sched.h>
  22 #include <net/pkt_cls.h>
  23 #include <net/codel.h>
  24 #include <net/codel_impl.h>
  25 #include <net/codel_qdisc.h>
  26
  27 /*      Fair Queue CoDel.
  28  *
  29  * Principles :
  30  * Packets are classified (internal classifier or external) on flows.
  31  * This is a Stochastic model (as we use a hash, several flows
  32  *                             might be hashed on same slot)
  33  * Each flow has a CoDel managed queue.
  34  * Flows are linked onto two (Round Robin) lists,
  35  * so that new flows have priority on old ones.
  36  *
  37  * For a given flow, packets are not reordered (CoDel uses a FIFO)
  38  * head drops only.
  39  * ECN capability is on by default.
  40  * Low memory footprint (64 bytes per flow)
  41  */
  42
  43 struct fq_codel_flow {
  44         struct sk_buff    *head;
  45         struct sk_buff    *tail;
  46         struct list_head  flowchain;
  47         int               deficit;
  48         struct codel_vars cvars;
  49 }; /* please try to keep this structure <= 64 bytes */
  50
  51 struct fq_codel_sched_data {
  52         struct tcf_proto __rcu *filter_list; /* optional external classifier */
  53         struct tcf_block *block;
  54         struct fq_codel_flow *flows;    /* Flows table [flows_cnt] */
  55         u32             *backlogs;      /* backlog table [flows_cnt] */
  56         u32             flows_cnt;      /* number of flows */
  57         u32             quantum;        /* psched_mtu(qdisc_dev(sch)); */
  58         u32             drop_batch_size;
  59         u32             memory_limit;
  60         struct codel_params cparams;
  61         struct codel_stats cstats;
  62         u32             memory_usage;
  63         u32             drop_overmemory;
  64         u32             drop_overlimit;
  65         u32             new_flow_count;
  66
  67         struct list_head new_flows;     /* list of new flows */
  68         struct list_head old_flows;     /* list of old flows */
  69 };
  70
  71 static unsigned int fq_codel_hash(const struct fq_codel_sched_data *q,
  72                                   struct sk_buff *skb)
  73 {
  74         return reciprocal_scale(skb_get_hash(skb), q->flows_cnt);
  75 }
  76
  77 static unsigned int fq_codel_classify(struct sk_buff *skb, struct Qdisc *sch,
  78                                       int *qerr)
  79 {
  80         struct fq_codel_sched_data *q = qdisc_priv(sch);
  81         struct tcf_proto *filter;
  82         struct tcf_result res;
  83         int result;
  84
  85         if (TC_H_MAJ(skb->priority) == sch->handle &&
  86             TC_H_MIN(skb->priority) > 0 &&
  87             TC_H_MIN(skb->priority) <= q->flows_cnt)
  88                 return TC_H_MIN(skb->priority);
  89
  90         filter = rcu_dereference_bh(q->filter_list);
  91         if (!filter)
  92                 return fq_codel_hash(q, skb) + 1;
  93
  94         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
  95         result = tcf_classify(skb, filter, &res, false);
  96         if (result >= 0) {
  97 #ifdef CONFIG_NET_CLS_ACT
  98                 switch (result) {
  99                 case TC_ACT_STOLEN:
 100                 case TC_ACT_QUEUED:
 101                 case TC_ACT_TRAP:
 102                         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
 103                         /* fall through */
 104                 case TC_ACT_SHOT:
 105                         return 0;
 106                 }
 107 #endif
 108                 if (TC_H_MIN(res.classid) <= q->flows_cnt)
 109                         return TC_H_MIN(res.classid);
 110         }
 111         return 0;
 112 }
 113
 114 /* helper functions : might be changed when/if skb use a standard list_head */
 115
 116 /* remove one skb from head of slot queue */
 117 static inline struct sk_buff *dequeue_head(struct fq_codel_flow *flow)
 118 {
 119         struct sk_buff *skb = flow->head;
 120
 121         flow->head = skb->next;
 122         skb_mark_not_on_list(skb);
 123         return skb;
 124 }
 125
 126 /* add skb to flow queue (tail add) */
 127 static inline void flow_queue_add(struct fq_codel_flow *flow,
 128                                   struct sk_buff *skb)
 129 {
 130         if (flow->head == NULL)
 131                 flow->head = skb;
 132         else
 133                 flow->tail->next = skb;
 134         flow->tail = skb;
 135         skb->next = NULL;
 136 }
 137
 138 static unsigned int fq_codel_drop(struct Qdisc *sch, unsigned int max_packets,
 139                                   struct sk_buff **to_free)
 140 {
 141         struct fq_codel_sched_data *q = qdisc_priv(sch);
 142         struct sk_buff *skb;
 143         unsigned int maxbacklog = 0, idx = 0, i, len;
 144         struct fq_codel_flow *flow;
 145         unsigned int threshold;
 146         unsigned int mem = 0;
 147
 148         /* Queue is full! Find the fat flow and drop packet(s) from it.
 149          * This might sound expensive, but with 1024 flows, we scan
 150          * 4KB of memory, and we dont need to handle a complex tree
 151          * in fast path (packet queue/enqueue) with many cache misses.
 152          * In stress mode, we'll try to drop 64 packets from the flow,
 153          * amortizing this linear lookup to one cache line per drop.
 154          */
 155         for (i = 0; i < q->flows_cnt; i++) {
 156                 if (q->backlogs[i] > maxbacklog) {
 157                         maxbacklog = q->backlogs[i];
 158                         idx = i;
 159                 }
 160         }
 161
 162         /* Our goal is to drop half of this fat flow backlog */
 163         threshold = maxbacklog >> 1;
 164
 165         flow = &q->flows[idx];
 166         len = 0;
 167         i = 0;
 168         do {
 169                 skb = dequeue_head(flow);
 170                 len += qdisc_pkt_len(skb);
 171                 mem += get_codel_cb(skb)->mem_usage;
 172                 __qdisc_drop(skb, to_free);
 173         } while (++i < max_packets && len < threshold);
 174
 175         /* Tell codel to increase its signal strength also */
 176         flow->cvars.count += i;
 177         q->backlogs[idx] -= len;
 178         q->memory_usage -= mem;
 179         sch->qstats.drops += i;
 180         sch->qstats.backlog -= len;
 181         sch->q.qlen -= i;
 182         return idx;
 183 }
 184
 185 static int fq_codel_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 186                             struct sk_buff **to_free)
 187 {
 188         struct fq_codel_sched_data *q = qdisc_priv(sch);
 189         unsigned int idx, prev_backlog, prev_qlen;
 190         struct fq_codel_flow *flow;
 191         int ret;
 192         unsigned int pkt_len;
 193         bool memory_limited;
 194
 195         idx = fq_codel_classify(skb, sch, &ret);
 196         if (idx == 0) {
 197                 if (ret & __NET_XMIT_BYPASS)
 198                         qdisc_qstats_drop(sch);
 199                 __qdisc_drop(skb, to_free);
 200                 return ret;
 201         }
 202         idx--;
 203
 204         codel_set_enqueue_time(skb);
 205         flow = &q->flows[idx];
 206         flow_queue_add(flow, skb);
 207         q->backlogs[idx] += qdisc_pkt_len(skb);
 208         qdisc_qstats_backlog_inc(sch, skb);
 209
 210         if (list_empty(&flow->flowchain)) {
 211                 list_add_tail(&flow->flowchain, &q->new_flows);
 212                 q->new_flow_count++;
 213                 flow->deficit = q->quantum;
 214         }
 215         get_codel_cb(skb)->mem_usage = skb->truesize;
 216         q->memory_usage += get_codel_cb(skb)->mem_usage;
 217         memory_limited = q->memory_usage > q->memory_limit;
 218         if (++sch->q.qlen <= sch->limit && !memory_limited)
 219                 return NET_XMIT_SUCCESS;
 220
 221         prev_backlog = sch->qstats.backlog;
 222         prev_qlen = sch->q.qlen;
 223
 224         /* save this packet length as it might be dropped by fq_codel_drop() */
 225         pkt_len = qdisc_pkt_len(skb);
 226         /* fq_codel_drop() is quite expensive, as it performs a linear search
 227          * in q->backlogs[] to find a fat flow.
 228          * So instead of dropping a single packet, drop half of its backlog
 229          * with a 64 packets limit to not add a too big cpu spike here.
 230          */
 231         ret = fq_codel_drop(sch, q->drop_batch_size, to_free);
 232
 233         prev_qlen -= sch->q.qlen;
 234         prev_backlog -= sch->qstats.backlog;
 235         q->drop_overlimit += prev_qlen;
 236         if (memory_limited)
 237                 q->drop_overmemory += prev_qlen;
 238
 239         /* As we dropped packet(s), better let upper stack know this.
 240          * If we dropped a packet for this flow, return NET_XMIT_CN,
 241          * but in this case, our parents wont increase their backlogs.
 242          */
 243         if (ret == idx) {
 244                 qdisc_tree_reduce_backlog(sch, prev_qlen - 1,
 245                                           prev_backlog - pkt_len);
 246                 return NET_XMIT_CN;
 247         }
 248         qdisc_tree_reduce_backlog(sch, prev_qlen, prev_backlog);
 249         return NET_XMIT_SUCCESS;
 250 }
 251
 252 /* This is the specific function called from codel_dequeue()
 253  * to dequeue a packet from queue. Note: backlog is handled in
 254  * codel, we dont need to reduce it here.
 255  */
 256 static struct sk_buff *dequeue_func(struct codel_vars *vars, void *ctx)
 257 {
 258         struct Qdisc *sch = ctx;
 259         struct fq_codel_sched_data *q = qdisc_priv(sch);
 260         struct fq_codel_flow *flow;
 261         struct sk_buff *skb = NULL;
 262
 263         flow = container_of(vars, struct fq_codel_flow, cvars);
 264         if (flow->head) {
 265                 skb = dequeue_head(flow);
 266                 q->backlogs[flow - q->flows] -= qdisc_pkt_len(skb);
 267                 q->memory_usage -= get_codel_cb(skb)->mem_usage;
 268                 sch->q.qlen--;
 269                 sch->qstats.backlog -= qdisc_pkt_len(skb);
 270         }
 271         return skb;
 272 }
 273
 274 static void drop_func(struct sk_buff *skb, void *ctx)
 275 {
 276         struct Qdisc *sch = ctx;
 277
 278         kfree_skb(skb);
 279         qdisc_qstats_drop(sch);
 280 }
 281
 282 static struct sk_buff *fq_codel_dequeue(struct Qdisc *sch)
 283 {
 284         struct fq_codel_sched_data *q = qdisc_priv(sch);
 285         struct sk_buff *skb;
 286         struct fq_codel_flow *flow;
 287         struct list_head *head;
 288
 289 begin:
 290         head = &q->new_flows;
 291         if (list_empty(head)) {
 292                 head = &q->old_flows;
 293                 if (list_empty(head))
 294                         return NULL;
 295         }
 296         flow = list_first_entry(head, struct fq_codel_flow, flowchain);
 297
 298         if (flow->deficit <= 0) {
 299                 flow->deficit += q->quantum;
 300                 list_move_tail(&flow->flowchain, &q->old_flows);
 301                 goto begin;
 302         }
 303
 304         skb = codel_dequeue(sch, &sch->qstats.backlog, &q->cparams,
 305                             &flow->cvars, &q->cstats, qdisc_pkt_len,
 306                             codel_get_enqueue_time, drop_func, dequeue_func);
 307
 308         if (!skb) {
 309                 /* force a pass through old_flows to prevent starvation */
 310                 if ((head == &q->new_flows) && !list_empty(&q->old_flows))
 311                         list_move_tail(&flow->flowchain, &q->old_flows);
 312                 else
 313                         list_del_init(&flow->flowchain);
 314                 goto begin;
 315         }
 316         qdisc_bstats_update(sch, skb);
 317         flow->deficit -= qdisc_pkt_len(skb);
 318         /* We cant call qdisc_tree_reduce_backlog() if our qlen is 0,
 319          * or HTB crashes. Defer it for next round.
 320          */
 321         if (q->cstats.drop_count && sch->q.qlen) {
 322                 qdisc_tree_reduce_backlog(sch, q->cstats.drop_count,
 323                                           q->cstats.drop_len);
 324                 q->cstats.drop_count = 0;
 325                 q->cstats.drop_len = 0;
 326         }
 327         return skb;
 328 }
 329
 330 static void fq_codel_flow_purge(struct fq_codel_flow *flow)
 331 {
 332         rtnl_kfree_skbs(flow->head, flow->tail);
 333         flow->head = NULL;
 334 }
 335
 336 static void fq_codel_reset(struct Qdisc *sch)
 337 {
 338         struct fq_codel_sched_data *q = qdisc_priv(sch);
 339         int i;
 340
 341         INIT_LIST_HEAD(&q->new_flows);
 342         INIT_LIST_HEAD(&q->old_flows);
 343         for (i = 0; i < q->flows_cnt; i++) {
 344                 struct fq_codel_flow *flow = q->flows + i;
 345
 346                 fq_codel_flow_purge(flow);
 347                 INIT_LIST_HEAD(&flow->flowchain);
 348                 codel_vars_init(&flow->cvars);
 349         }
 350         memset(q->backlogs, 0, q->flows_cnt * sizeof(u32));
 351         sch->q.qlen = 0;
 352         sch->qstats.backlog = 0;
 353         q->memory_usage = 0;
 354 }
 355
 356 static const struct nla_policy fq_codel_policy[TCA_FQ_CODEL_MAX + 1] = {
 357         [TCA_FQ_CODEL_TARGET]   = { .type = NLA_U32 },
 358         [TCA_FQ_CODEL_LIMIT]    = { .type = NLA_U32 },
 359         [TCA_FQ_CODEL_INTERVAL] = { .type = NLA_U32 },
 360         [TCA_FQ_CODEL_ECN]      = { .type = NLA_U32 },
 361         [TCA_FQ_CODEL_FLOWS]    = { .type = NLA_U32 },
 362         [TCA_FQ_CODEL_QUANTUM]  = { .type = NLA_U32 },
 363         [TCA_FQ_CODEL_CE_THRESHOLD] = { .type = NLA_U32 },
 364         [TCA_FQ_CODEL_DROP_BATCH_SIZE] = { .type = NLA_U32 },
 365         [TCA_FQ_CODEL_MEMORY_LIMIT] = { .type = NLA_U32 },
 366 };
 367
 368 static int fq_codel_change(struct Qdisc *sch, struct nlattr *opt,
 369                            struct netlink_ext_ack *extack)
 370 {
 371         struct fq_codel_sched_data *q = qdisc_priv(sch);
 372         struct nlattr *tb[TCA_FQ_CODEL_MAX + 1];
 373         u32 quantum = 0;
 374         int err;
 375
 376         if (!opt)
 377                 return -EINVAL;
 378
 379         err = nla_parse_nested_deprecated(tb, TCA_FQ_CODEL_MAX, opt,
 380                                           fq_codel_policy, NULL);
 381         if (err < 0)
 382                 return err;
 383         if (tb[TCA_FQ_CODEL_FLOWS]) {
 384                 if (q->flows)
 385                         return -EINVAL;
 386                 q->flows_cnt = nla_get_u32(tb[TCA_FQ_CODEL_FLOWS]);
 387                 if (!q->flows_cnt ||
 388                     q->flows_cnt > 65536)
 389                         return -EINVAL;
 390         }
 391         if (tb[TCA_FQ_CODEL_QUANTUM]) {
 392                 quantum = max(256U, nla_get_u32(tb[TCA_FQ_CODEL_QUANTUM]));
 393                 if (quantum > FQ_CODEL_QUANTUM_MAX) {
 394                         NL_SET_ERR_MSG(extack, "Invalid quantum");
 395                         return -EINVAL;
 396                 }
 397         }
 398         sch_tree_lock(sch);
 399
 400         if (tb[TCA_FQ_CODEL_TARGET]) {
 401                 u64 target = nla_get_u32(tb[TCA_FQ_CODEL_TARGET]);
 402
 403                 q->cparams.target = (target * NSEC_PER_USEC) >> CODEL_SHIFT;
 404         }
 405
 406         if (tb[TCA_FQ_CODEL_CE_THRESHOLD]) {
 407                 u64 val = nla_get_u32(tb[TCA_FQ_CODEL_CE_THRESHOLD]);
 408
 409                 q->cparams.ce_threshold = (val * NSEC_PER_USEC) >> CODEL_SHIFT;
 410         }
 411
 412         if (tb[TCA_FQ_CODEL_INTERVAL]) {
 413                 u64 interval = nla_get_u32(tb[TCA_FQ_CODEL_INTERVAL]);
 414
 415                 q->cparams.interval = (interval * NSEC_PER_USEC) >> CODEL_SHIFT;
 416         }
 417
 418         if (tb[TCA_FQ_CODEL_LIMIT])
 419                 sch->limit = nla_get_u32(tb[TCA_FQ_CODEL_LIMIT]);
 420
 421         if (tb[TCA_FQ_CODEL_ECN])
 422                 q->cparams.ecn = !!nla_get_u32(tb[TCA_FQ_CODEL_ECN]);
 423
 424         if (quantum)
 425                 q->quantum = quantum;
 426
 427         if (tb[TCA_FQ_CODEL_DROP_BATCH_SIZE])
 428                 q->drop_batch_size = max(1U, nla_get_u32(tb[TCA_FQ_CODEL_DROP_BATCH_SIZE]));
 429
 430         if (tb[TCA_FQ_CODEL_MEMORY_LIMIT])
 431                 q->memory_limit = min(1U << 31, nla_get_u32(tb[TCA_FQ_CODEL_MEMORY_LIMIT]));
 432
 433         while (sch->q.qlen > sch->limit ||
 434                q->memory_usage > q->memory_limit) {
 435                 struct sk_buff *skb = fq_codel_dequeue(sch);
 436
 437                 q->cstats.drop_len += qdisc_pkt_len(skb);
 438                 rtnl_kfree_skbs(skb, skb);
 439                 q->cstats.drop_count++;
 440         }
 441         qdisc_tree_reduce_backlog(sch, q->cstats.drop_count, q->cstats.drop_len);
 442         q->cstats.drop_count = 0;
 443         q->cstats.drop_len = 0;
 444
 445         sch_tree_unlock(sch);
 446         return 0;
 447 }
 448
 449 static void fq_codel_destroy(struct Qdisc *sch)
 450 {
 451         struct fq_codel_sched_data *q = qdisc_priv(sch);
 452
 453         tcf_block_put(q->block);
 454         kvfree(q->backlogs);
 455         kvfree(q->flows);
 456 }
 457
 458 static int fq_codel_init(struct Qdisc *sch, struct nlattr *opt,
 459                          struct netlink_ext_ack *extack)
 460 {
 461         struct fq_codel_sched_data *q = qdisc_priv(sch);
 462         int i;
 463         int err;
 464
 465         sch->limit = 10*1024;
 466         q->flows_cnt = 1024;
 467         q->memory_limit = 32 << 20; /* 32 MBytes */
 468         q->drop_batch_size = 64;
 469         q->quantum = psched_mtu(qdisc_dev(sch));
 470         INIT_LIST_HEAD(&q->new_flows);
 471         INIT_LIST_HEAD(&q->old_flows);
 472         codel_params_init(&q->cparams);
 473         codel_stats_init(&q->cstats);
 474         q->cparams.ecn = true;
 475         q->cparams.mtu = psched_mtu(qdisc_dev(sch));
 476
 477         if (opt) {
 478                 err = fq_codel_change(sch, opt, extack);
 479                 if (err)
 480                         goto init_failure;
 481         }
 482
 483         err = tcf_block_get(&q->block, &q->filter_list, sch, extack);
 484         if (err)
 485                 goto init_failure;
 486
 487         if (!q->flows) {
 488                 q->flows = kvcalloc(q->flows_cnt,
 489                                     sizeof(struct fq_codel_flow),
 490                                     GFP_KERNEL);
 491                 if (!q->flows) {
 492                         err = -ENOMEM;
 493                         goto init_failure;
 494                 }
 495                 q->backlogs = kvcalloc(q->flows_cnt, sizeof(u32), GFP_KERNEL);
 496                 if (!q->backlogs) {
 497                         err = -ENOMEM;
 498                         goto alloc_failure;
 499                 }
 500                 for (i = 0; i < q->flows_cnt; i++) {
 501                         struct fq_codel_flow *flow = q->flows + i;
 502
 503                         INIT_LIST_HEAD(&flow->flowchain);
 504                         codel_vars_init(&flow->cvars);
 505                 }
 506         }
 507         if (sch->limit >= 1)
 508                 sch->flags |= TCQ_F_CAN_BYPASS;
 509         else
 510                 sch->flags &= ~TCQ_F_CAN_BYPASS;
 511         return 0;
 512
 513 alloc_failure:
 514         kvfree(q->flows);
 515         q->flows = NULL;
 516 init_failure:
 517         q->flows_cnt = 0;
 518         return err;
 519 }
 520
 521 static int fq_codel_dump(struct Qdisc *sch, struct sk_buff *skb)
 522 {
 523         struct fq_codel_sched_data *q = qdisc_priv(sch);
 524         struct nlattr *opts;
 525
 526         opts = nla_nest_start_noflag(skb, TCA_OPTIONS);
 527         if (opts == NULL)
 528                 goto nla_put_failure;
 529
 530         if (nla_put_u32(skb, TCA_FQ_CODEL_TARGET,
 531                         codel_time_to_us(q->cparams.target)) ||
 532             nla_put_u32(skb, TCA_FQ_CODEL_LIMIT,
 533                         sch->limit) ||
 534             nla_put_u32(skb, TCA_FQ_CODEL_INTERVAL,
 535                         codel_time_to_us(q->cparams.interval)) ||
 536             nla_put_u32(skb, TCA_FQ_CODEL_ECN,
 537                         q->cparams.ecn) ||
 538             nla_put_u32(skb, TCA_FQ_CODEL_QUANTUM,
 539                         q->quantum) ||
 540             nla_put_u32(skb, TCA_FQ_CODEL_DROP_BATCH_SIZE,
 541                         q->drop_batch_size) ||
 542             nla_put_u32(skb, TCA_FQ_CODEL_MEMORY_LIMIT,
 543                         q->memory_limit) ||
 544             nla_put_u32(skb, TCA_FQ_CODEL_FLOWS,
 545                         q->flows_cnt))
 546                 goto nla_put_failure;
 547
 548         if (q->cparams.ce_threshold != CODEL_DISABLED_THRESHOLD &&
 549             nla_put_u32(skb, TCA_FQ_CODEL_CE_THRESHOLD,
 550                         codel_time_to_us(q->cparams.ce_threshold)))
 551                 goto nla_put_failure;
 552
 553         return nla_nest_end(skb, opts);
 554
 555 nla_put_failure:
 556         return -1;
 557 }
 558
 559 static int fq_codel_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
 560 {
 561         struct fq_codel_sched_data *q = qdisc_priv(sch);
 562         struct tc_fq_codel_xstats st = {
 563                 .type                           = TCA_FQ_CODEL_XSTATS_QDISC,
 564         };
 565         struct list_head *pos;
 566
 567         st.qdisc_stats.maxpacket = q->cstats.maxpacket;
 568         st.qdisc_stats.drop_overlimit = q->drop_overlimit;
 569         st.qdisc_stats.ecn_mark = q->cstats.ecn_mark;
 570         st.qdisc_stats.new_flow_count = q->new_flow_count;
 571         st.qdisc_stats.ce_mark = q->cstats.ce_mark;
 572         st.qdisc_stats.memory_usage  = q->memory_usage;
 573         st.qdisc_stats.drop_overmemory = q->drop_overmemory;
 574
 575         sch_tree_lock(sch);
 576         list_for_each(pos, &q->new_flows)
 577                 st.qdisc_stats.new_flows_len++;
 578
 579         list_for_each(pos, &q->old_flows)
 580                 st.qdisc_stats.old_flows_len++;
 581         sch_tree_unlock(sch);
 582
 583         return gnet_stats_copy_app(d, &st, sizeof(st));
 584 }
 585
 586 static struct Qdisc *fq_codel_leaf(struct Qdisc *sch, unsigned long arg)
 587 {
 588         return NULL;
 589 }
 590
 591 static unsigned long fq_codel_find(struct Qdisc *sch, u32 classid)
 592 {
 593         return 0;
 594 }
 595
 596 static unsigned long fq_codel_bind(struct Qdisc *sch, unsigned long parent,
 597                               u32 classid)
 598 {
 599         return 0;
 600 }
 601
 602 static void fq_codel_unbind(struct Qdisc *q, unsigned long cl)
 603 {
 604 }
 605
 606 static struct tcf_block *fq_codel_tcf_block(struct Qdisc *sch, unsigned long cl,
 607                                             struct netlink_ext_ack *extack)
 608 {
 609         struct fq_codel_sched_data *q = qdisc_priv(sch);
 610
 611         if (cl)
 612                 return NULL;
 613         return q->block;
 614 }
 615
 616 static int fq_codel_dump_class(struct Qdisc *sch, unsigned long cl,
 617                           struct sk_buff *skb, struct tcmsg *tcm)
 618 {
 619         tcm->tcm_handle |= TC_H_MIN(cl);
 620         return 0;
 621 }
 622
 623 static int fq_codel_dump_class_stats(struct Qdisc *sch, unsigned long cl,
 624                                      struct gnet_dump *d)
 625 {
 626         struct fq_codel_sched_data *q = qdisc_priv(sch);
 627         u32 idx = cl - 1;
 628         struct gnet_stats_queue qs = { 0 };
 629         struct tc_fq_codel_xstats xstats;
 630
 631         if (idx < q->flows_cnt) {
 632                 const struct fq_codel_flow *flow = &q->flows[idx];
 633                 const struct sk_buff *skb;
 634
 635                 memset(&xstats, 0, sizeof(xstats));
 636                 xstats.type = TCA_FQ_CODEL_XSTATS_CLASS;
 637                 xstats.class_stats.deficit = flow->deficit;
 638                 xstats.class_stats.ldelay =
 639                         codel_time_to_us(flow->cvars.ldelay);
 640                 xstats.class_stats.count = flow->cvars.count;
 641                 xstats.class_stats.lastcount = flow->cvars.lastcount;
 642                 xstats.class_stats.dropping = flow->cvars.dropping;
 643                 if (flow->cvars.dropping) {
 644                         codel_tdiff_t delta = flow->cvars.drop_next -
 645                                               codel_get_time();
 646
 647                         xstats.class_stats.drop_next = (delta >= 0) ?
 648                                 codel_time_to_us(delta) :
 649                                 -codel_time_to_us(-delta);
 650                 }
 651                 if (flow->head) {
 652                         sch_tree_lock(sch);
 653                         skb = flow->head;
 654                         while (skb) {
 655                                 qs.qlen++;
 656                                 skb = skb->next;
 657                         }
 658                         sch_tree_unlock(sch);
 659                 }
 660                 qs.backlog = q->backlogs[idx];
 661                 qs.drops = 0;
 662         }
 663         if (gnet_stats_copy_queue(d, NULL, &qs, qs.qlen) < 0)
 664                 return -1;
 665         if (idx < q->flows_cnt)
 666                 return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
 667         return 0;
 668 }
 669
 670 static void fq_codel_walk(struct Qdisc *sch, struct qdisc_walker *arg)
 671 {
 672         struct fq_codel_sched_data *q = qdisc_priv(sch);
 673         unsigned int i;
 674
 675         if (arg->stop)
 676                 return;
 677
 678         for (i = 0; i < q->flows_cnt; i++) {
 679                 if (list_empty(&q->flows[i].flowchain) ||
 680                     arg->count < arg->skip) {
 681                         arg->count++;
 682                         continue;
 683                 }
 684                 if (arg->fn(sch, i + 1, arg) < 0) {
 685                         arg->stop = 1;
 686                         break;
 687                 }
 688                 arg->count++;
 689         }
 690 }
 691
 692 static const struct Qdisc_class_ops fq_codel_class_ops = {
 693         .leaf           =       fq_codel_leaf,
 694         .find           =       fq_codel_find,
 695         .tcf_block      =       fq_codel_tcf_block,
 696         .bind_tcf       =       fq_codel_bind,
 697         .unbind_tcf     =       fq_codel_unbind,
 698         .dump           =       fq_codel_dump_class,
 699         .dump_stats     =       fq_codel_dump_class_stats,
 700         .walk           =       fq_codel_walk,
 701 };
 702
 703 static struct Qdisc_ops fq_codel_qdisc_ops __read_mostly = {
 704         .cl_ops         =       &fq_codel_class_ops,
 705         .id             =       "fq_codel",
 706         .priv_size      =       sizeof(struct fq_codel_sched_data),
 707         .enqueue        =       fq_codel_enqueue,
 708         .dequeue        =       fq_codel_dequeue,
 709         .peek           =       qdisc_peek_dequeued,
 710         .init           =       fq_codel_init,
 711         .reset          =       fq_codel_reset,
 712         .destroy        =       fq_codel_destroy,
 713         .change         =       fq_codel_change,
 714         .dump           =       fq_codel_dump,
 715         .dump_stats =   fq_codel_dump_stats,
 716         .owner          =       THIS_MODULE,
 717 };
 718
 719 static int __init fq_codel_module_init(void)
 720 {
 721         return register_qdisc(&fq_codel_qdisc_ops);
 722 }
 723
 724 static void __exit fq_codel_module_exit(void)
 725 {
 726         unregister_qdisc(&fq_codel_qdisc_ops);
 727 }
 728
 729 module_init(fq_codel_module_init)
 730 module_exit(fq_codel_module_exit)
 731 MODULE_AUTHOR("Eric Dumazet");
 732 MODULE_LICENSE("GPL");