root/net/sched/sch_fq_codel.c

DEFINITIONS

1. fq_codel_hash
2. fq_codel_classify
3. dequeue_head
4. flow_queue_add
5. fq_codel_drop
6. fq_codel_enqueue
7. dequeue_func
8. drop_func
9. fq_codel_dequeue
10. fq_codel_flow_purge
11. fq_codel_reset
12. fq_codel_change
13. fq_codel_destroy
14. fq_codel_init
15. fq_codel_dump
16. fq_codel_dump_stats
17. fq_codel_leaf
18. fq_codel_find
19. fq_codel_bind
20. fq_codel_unbind
21. fq_codel_tcf_block
22. fq_codel_dump_class
23. fq_codel_dump_class_stats
24. fq_codel_walk
25. fq_codel_module_init
26. fq_codel_module_exit

   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 uninitialized_var(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         int err;
 374 
 375         if (!opt)
 376                 return -EINVAL;
 377 
 378         err = nla_parse_nested_deprecated(tb, TCA_FQ_CODEL_MAX, opt,
 379                                           fq_codel_policy, NULL);
 380         if (err < 0)
 381                 return err;
 382         if (tb[TCA_FQ_CODEL_FLOWS]) {
 383                 if (q->flows)
 384                         return -EINVAL;
 385                 q->flows_cnt = nla_get_u32(tb[TCA_FQ_CODEL_FLOWS]);
 386                 if (!q->flows_cnt ||
 387                     q->flows_cnt > 65536)
 388                         return -EINVAL;
 389         }
 390         sch_tree_lock(sch);
 391 
 392         if (tb[TCA_FQ_CODEL_TARGET]) {
 393                 u64 target = nla_get_u32(tb[TCA_FQ_CODEL_TARGET]);
 394 
 395                 q->cparams.target = (target * NSEC_PER_USEC) >> CODEL_SHIFT;
 396         }
 397 
 398         if (tb[TCA_FQ_CODEL_CE_THRESHOLD]) {
 399                 u64 val = nla_get_u32(tb[TCA_FQ_CODEL_CE_THRESHOLD]);
 400 
 401                 q->cparams.ce_threshold = (val * NSEC_PER_USEC) >> CODEL_SHIFT;
 402         }
 403 
 404         if (tb[TCA_FQ_CODEL_INTERVAL]) {
 405                 u64 interval = nla_get_u32(tb[TCA_FQ_CODEL_INTERVAL]);
 406 
 407                 q->cparams.interval = (interval * NSEC_PER_USEC) >> CODEL_SHIFT;
 408         }
 409 
 410         if (tb[TCA_FQ_CODEL_LIMIT])
 411                 sch->limit = nla_get_u32(tb[TCA_FQ_CODEL_LIMIT]);
 412 
 413         if (tb[TCA_FQ_CODEL_ECN])
 414                 q->cparams.ecn = !!nla_get_u32(tb[TCA_FQ_CODEL_ECN]);
 415 
 416         if (tb[TCA_FQ_CODEL_QUANTUM])
 417                 q->quantum = max(256U, nla_get_u32(tb[TCA_FQ_CODEL_QUANTUM]));
 418 
 419         if (tb[TCA_FQ_CODEL_DROP_BATCH_SIZE])
 420                 q->drop_batch_size = max(1U, nla_get_u32(tb[TCA_FQ_CODEL_DROP_BATCH_SIZE]));
 421 
 422         if (tb[TCA_FQ_CODEL_MEMORY_LIMIT])
 423                 q->memory_limit = min(1U << 31, nla_get_u32(tb[TCA_FQ_CODEL_MEMORY_LIMIT]));
 424 
 425         while (sch->q.qlen > sch->limit ||
 426                q->memory_usage > q->memory_limit) {
 427                 struct sk_buff *skb = fq_codel_dequeue(sch);
 428 
 429                 q->cstats.drop_len += qdisc_pkt_len(skb);
 430                 rtnl_kfree_skbs(skb, skb);
 431                 q->cstats.drop_count++;
 432         }
 433         qdisc_tree_reduce_backlog(sch, q->cstats.drop_count, q->cstats.drop_len);
 434         q->cstats.drop_count = 0;
 435         q->cstats.drop_len = 0;
 436 
 437         sch_tree_unlock(sch);
 438         return 0;
 439 }
 440 
 441 static void fq_codel_destroy(struct Qdisc *sch)
 442 {
 443         struct fq_codel_sched_data *q = qdisc_priv(sch);
 444 
 445         tcf_block_put(q->block);
 446         kvfree(q->backlogs);
 447         kvfree(q->flows);
 448 }
 449 
 450 static int fq_codel_init(struct Qdisc *sch, struct nlattr *opt,
 451                          struct netlink_ext_ack *extack)
 452 {
 453         struct fq_codel_sched_data *q = qdisc_priv(sch);
 454         int i;
 455         int err;
 456 
 457         sch->limit = 10*1024;
 458         q->flows_cnt = 1024;
 459         q->memory_limit = 32 << 20; /* 32 MBytes */
 460         q->drop_batch_size = 64;
 461         q->quantum = psched_mtu(qdisc_dev(sch));
 462         INIT_LIST_HEAD(&q->new_flows);
 463         INIT_LIST_HEAD(&q->old_flows);
 464         codel_params_init(&q->cparams);
 465         codel_stats_init(&q->cstats);
 466         q->cparams.ecn = true;
 467         q->cparams.mtu = psched_mtu(qdisc_dev(sch));
 468 
 469         if (opt) {
 470                 err = fq_codel_change(sch, opt, extack);
 471                 if (err)
 472                         goto init_failure;
 473         }
 474 
 475         err = tcf_block_get(&q->block, &q->filter_list, sch, extack);
 476         if (err)
 477                 goto init_failure;
 478 
 479         if (!q->flows) {
 480                 q->flows = kvcalloc(q->flows_cnt,
 481                                     sizeof(struct fq_codel_flow),
 482                                     GFP_KERNEL);
 483                 if (!q->flows) {
 484                         err = -ENOMEM;
 485                         goto init_failure;
 486                 }
 487                 q->backlogs = kvcalloc(q->flows_cnt, sizeof(u32), GFP_KERNEL);
 488                 if (!q->backlogs) {
 489                         err = -ENOMEM;
 490                         goto alloc_failure;
 491                 }
 492                 for (i = 0; i < q->flows_cnt; i++) {
 493                         struct fq_codel_flow *flow = q->flows + i;
 494 
 495                         INIT_LIST_HEAD(&flow->flowchain);
 496                         codel_vars_init(&flow->cvars);
 497                 }
 498         }
 499         if (sch->limit >= 1)
 500                 sch->flags |= TCQ_F_CAN_BYPASS;
 501         else
 502                 sch->flags &= ~TCQ_F_CAN_BYPASS;
 503         return 0;
 504 
 505 alloc_failure:
 506         kvfree(q->flows);
 507         q->flows = NULL;
 508 init_failure:
 509         q->flows_cnt = 0;
 510         return err;
 511 }
 512 
 513 static int fq_codel_dump(struct Qdisc *sch, struct sk_buff *skb)
 514 {
 515         struct fq_codel_sched_data *q = qdisc_priv(sch);
 516         struct nlattr *opts;
 517 
 518         opts = nla_nest_start_noflag(skb, TCA_OPTIONS);
 519         if (opts == NULL)
 520                 goto nla_put_failure;
 521 
 522         if (nla_put_u32(skb, TCA_FQ_CODEL_TARGET,
 523                         codel_time_to_us(q->cparams.target)) ||
 524             nla_put_u32(skb, TCA_FQ_CODEL_LIMIT,
 525                         sch->limit) ||
 526             nla_put_u32(skb, TCA_FQ_CODEL_INTERVAL,
 527                         codel_time_to_us(q->cparams.interval)) ||
 528             nla_put_u32(skb, TCA_FQ_CODEL_ECN,
 529                         q->cparams.ecn) ||
 530             nla_put_u32(skb, TCA_FQ_CODEL_QUANTUM,
 531                         q->quantum) ||
 532             nla_put_u32(skb, TCA_FQ_CODEL_DROP_BATCH_SIZE,
 533                         q->drop_batch_size) ||
 534             nla_put_u32(skb, TCA_FQ_CODEL_MEMORY_LIMIT,
 535                         q->memory_limit) ||
 536             nla_put_u32(skb, TCA_FQ_CODEL_FLOWS,
 537                         q->flows_cnt))
 538                 goto nla_put_failure;
 539 
 540         if (q->cparams.ce_threshold != CODEL_DISABLED_THRESHOLD &&
 541             nla_put_u32(skb, TCA_FQ_CODEL_CE_THRESHOLD,
 542                         codel_time_to_us(q->cparams.ce_threshold)))
 543                 goto nla_put_failure;
 544 
 545         return nla_nest_end(skb, opts);
 546 
 547 nla_put_failure:
 548         return -1;
 549 }
 550 
 551 static int fq_codel_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
 552 {
 553         struct fq_codel_sched_data *q = qdisc_priv(sch);
 554         struct tc_fq_codel_xstats st = {
 555                 .type                           = TCA_FQ_CODEL_XSTATS_QDISC,
 556         };
 557         struct list_head *pos;
 558 
 559         st.qdisc_stats.maxpacket = q->cstats.maxpacket;
 560         st.qdisc_stats.drop_overlimit = q->drop_overlimit;
 561         st.qdisc_stats.ecn_mark = q->cstats.ecn_mark;
 562         st.qdisc_stats.new_flow_count = q->new_flow_count;
 563         st.qdisc_stats.ce_mark = q->cstats.ce_mark;
 564         st.qdisc_stats.memory_usage  = q->memory_usage;
 565         st.qdisc_stats.drop_overmemory = q->drop_overmemory;
 566 
 567         sch_tree_lock(sch);
 568         list_for_each(pos, &q->new_flows)
 569                 st.qdisc_stats.new_flows_len++;
 570 
 571         list_for_each(pos, &q->old_flows)
 572                 st.qdisc_stats.old_flows_len++;
 573         sch_tree_unlock(sch);
 574 
 575         return gnet_stats_copy_app(d, &st, sizeof(st));
 576 }
 577 
 578 static struct Qdisc *fq_codel_leaf(struct Qdisc *sch, unsigned long arg)
 579 {
 580         return NULL;
 581 }
 582 
 583 static unsigned long fq_codel_find(struct Qdisc *sch, u32 classid)
 584 {
 585         return 0;
 586 }
 587 
 588 static unsigned long fq_codel_bind(struct Qdisc *sch, unsigned long parent,
 589                               u32 classid)
 590 {
 591         return 0;
 592 }
 593 
 594 static void fq_codel_unbind(struct Qdisc *q, unsigned long cl)
 595 {
 596 }
 597 
 598 static struct tcf_block *fq_codel_tcf_block(struct Qdisc *sch, unsigned long cl,
 599                                             struct netlink_ext_ack *extack)
 600 {
 601         struct fq_codel_sched_data *q = qdisc_priv(sch);
 602 
 603         if (cl)
 604                 return NULL;
 605         return q->block;
 606 }
 607 
 608 static int fq_codel_dump_class(struct Qdisc *sch, unsigned long cl,
 609                           struct sk_buff *skb, struct tcmsg *tcm)
 610 {
 611         tcm->tcm_handle |= TC_H_MIN(cl);
 612         return 0;
 613 }
 614 
 615 static int fq_codel_dump_class_stats(struct Qdisc *sch, unsigned long cl,
 616                                      struct gnet_dump *d)
 617 {
 618         struct fq_codel_sched_data *q = qdisc_priv(sch);
 619         u32 idx = cl - 1;
 620         struct gnet_stats_queue qs = { 0 };
 621         struct tc_fq_codel_xstats xstats;
 622 
 623         if (idx < q->flows_cnt) {
 624                 const struct fq_codel_flow *flow = &q->flows[idx];
 625                 const struct sk_buff *skb;
 626 
 627                 memset(&xstats, 0, sizeof(xstats));
 628                 xstats.type = TCA_FQ_CODEL_XSTATS_CLASS;
 629                 xstats.class_stats.deficit = flow->deficit;
 630                 xstats.class_stats.ldelay =
 631                         codel_time_to_us(flow->cvars.ldelay);
 632                 xstats.class_stats.count = flow->cvars.count;
 633                 xstats.class_stats.lastcount = flow->cvars.lastcount;
 634                 xstats.class_stats.dropping = flow->cvars.dropping;
 635                 if (flow->cvars.dropping) {
 636                         codel_tdiff_t delta = flow->cvars.drop_next -
 637                                               codel_get_time();
 638 
 639                         xstats.class_stats.drop_next = (delta >= 0) ?
 640                                 codel_time_to_us(delta) :
 641                                 -codel_time_to_us(-delta);
 642                 }
 643                 if (flow->head) {
 644                         sch_tree_lock(sch);
 645                         skb = flow->head;
 646                         while (skb) {
 647                                 qs.qlen++;
 648                                 skb = skb->next;
 649                         }
 650                         sch_tree_unlock(sch);
 651                 }
 652                 qs.backlog = q->backlogs[idx];
 653                 qs.drops = 0;
 654         }
 655         if (gnet_stats_copy_queue(d, NULL, &qs, qs.qlen) < 0)
 656                 return -1;
 657         if (idx < q->flows_cnt)
 658                 return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
 659         return 0;
 660 }
 661 
 662 static void fq_codel_walk(struct Qdisc *sch, struct qdisc_walker *arg)
 663 {
 664         struct fq_codel_sched_data *q = qdisc_priv(sch);
 665         unsigned int i;
 666 
 667         if (arg->stop)
 668                 return;
 669 
 670         for (i = 0; i < q->flows_cnt; i++) {
 671                 if (list_empty(&q->flows[i].flowchain) ||
 672                     arg->count < arg->skip) {
 673                         arg->count++;
 674                         continue;
 675                 }
 676                 if (arg->fn(sch, i + 1, arg) < 0) {
 677                         arg->stop = 1;
 678                         break;
 679                 }
 680                 arg->count++;
 681         }
 682 }
 683 
 684 static const struct Qdisc_class_ops fq_codel_class_ops = {
 685         .leaf           =       fq_codel_leaf,
 686         .find           =       fq_codel_find,
 687         .tcf_block      =       fq_codel_tcf_block,
 688         .bind_tcf       =       fq_codel_bind,
 689         .unbind_tcf     =       fq_codel_unbind,
 690         .dump           =       fq_codel_dump_class,
 691         .dump_stats     =       fq_codel_dump_class_stats,
 692         .walk           =       fq_codel_walk,
 693 };
 694 
 695 static struct Qdisc_ops fq_codel_qdisc_ops __read_mostly = {
 696         .cl_ops         =       &fq_codel_class_ops,
 697         .id             =       "fq_codel",
 698         .priv_size      =       sizeof(struct fq_codel_sched_data),
 699         .enqueue        =       fq_codel_enqueue,
 700         .dequeue        =       fq_codel_dequeue,
 701         .peek           =       qdisc_peek_dequeued,
 702         .init           =       fq_codel_init,
 703         .reset          =       fq_codel_reset,
 704         .destroy        =       fq_codel_destroy,
 705         .change         =       fq_codel_change,
 706         .dump           =       fq_codel_dump,
 707         .dump_stats =   fq_codel_dump_stats,
 708         .owner          =       THIS_MODULE,
 709 };
 710 
 711 static int __init fq_codel_module_init(void)
 712 {
 713         return register_qdisc(&fq_codel_qdisc_ops);
 714 }
 715 
 716 static void __exit fq_codel_module_exit(void)
 717 {
 718         unregister_qdisc(&fq_codel_qdisc_ops);
 719 }
 720 
 721 module_init(fq_codel_module_init)
 722 module_exit(fq_codel_module_exit)
 723 MODULE_AUTHOR("Eric Dumazet");
 724 MODULE_LICENSE("GPL");