net/sched/sch_fq_codel.c

   1 /*
   2  * Fair Queue CoDel discipline
   3  *
   4  *      This program is free software; you can redistribute it and/or
   5  *      modify it under the terms of the GNU General Public License
   6  *      as published by the Free Software Foundation; either version
   7  *      2 of the License, or (at your option) any later version.
   8  *
   9  *  Copyright (C) 2012,2015 Eric Dumazet <edumazet@google.com>
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/types.h>
  14 #include <linux/kernel.h>
  15 #include <linux/jiffies.h>
  16 #include <linux/string.h>
  17 #include <linux/in.h>
  18 #include <linux/errno.h>
  19 #include <linux/init.h>
  20 #include <linux/skbuff.h>
  21 #include <linux/jhash.h>
  22 #include <linux/slab.h>
  23 #include <linux/vmalloc.h>
  24 #include <net/netlink.h>
  25 #include <net/pkt_sched.h>
  26 #include <net/codel.h>
  27
  28 /*      Fair Queue CoDel.
  29  *
  30  * Principles :
  31  * Packets are classified (internal classifier or external) on flows.
  32  * This is a Stochastic model (as we use a hash, several flows
  33  *                             might be hashed on same slot)
  34  * Each flow has a CoDel managed queue.
  35  * Flows are linked onto two (Round Robin) lists,
  36  * so that new flows have priority on old ones.
  37  *
  38  * For a given flow, packets are not reordered (CoDel uses a FIFO)
  39  * head drops only.
  40  * ECN capability is on by default.
  41  * Low memory footprint (64 bytes per flow)
  42  */
  43
  44 struct fq_codel_flow {
  45         struct sk_buff    *head;
  46         struct sk_buff    *tail;
  47         struct list_head  flowchain;
  48         int               deficit;
  49         u32               dropped; /* number of drops (or ECN marks) on this flow */
  50         struct codel_vars cvars;
  51 }; /* please try to keep this structure <= 64 bytes */
  52
  53 struct fq_codel_sched_data {
  54         struct tcf_proto __rcu *filter_list; /* optional external classifier */
  55         struct fq_codel_flow *flows;    /* Flows table [flows_cnt] */
  56         u32             *backlogs;      /* backlog table [flows_cnt] */
  57         u32             flows_cnt;      /* number of flows */
  58         u32             perturbation;   /* hash perturbation */
  59         u32             quantum;        /* psched_mtu(qdisc_dev(sch)); */
  60         struct codel_params cparams;
  61         struct codel_stats cstats;
  62         u32             drop_overlimit;
  63         u32             new_flow_count;
  64
  65         struct list_head new_flows;     /* list of new flows */
  66         struct list_head old_flows;     /* list of old flows */
  67 };
  68
  69 static unsigned int fq_codel_hash(const struct fq_codel_sched_data *q,
  70                                   struct sk_buff *skb)
  71 {
  72         u32 hash = skb_get_hash_perturb(skb, q->perturbation);
  73
  74         return reciprocal_scale(hash, 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 = tc_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                         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
 102                 case TC_ACT_SHOT:
 103                         return 0;
 104                 }
 105 #endif
 106                 if (TC_H_MIN(res.classid) <= q->flows_cnt)
 107                         return TC_H_MIN(res.classid);
 108         }
 109         return 0;
 110 }
 111
 112 /* helper functions : might be changed when/if skb use a standard list_head */
 113
 114 /* remove one skb from head of slot queue */
 115 static inline struct sk_buff *dequeue_head(struct fq_codel_flow *flow)
 116 {
 117         struct sk_buff *skb = flow->head;
 118
 119         flow->head = skb->next;
 120         skb->next = NULL;
 121         return skb;
 122 }
 123
 124 /* add skb to flow queue (tail add) */
 125 static inline void flow_queue_add(struct fq_codel_flow *flow,
 126                                   struct sk_buff *skb)
 127 {
 128         if (flow->head == NULL)
 129                 flow->head = skb;
 130         else
 131                 flow->tail->next = skb;
 132         flow->tail = skb;
 133         skb->next = NULL;
 134 }
 135
 136 static unsigned int fq_codel_drop(struct Qdisc *sch)
 137 {
 138         struct fq_codel_sched_data *q = qdisc_priv(sch);
 139         struct sk_buff *skb;
 140         unsigned int maxbacklog = 0, idx = 0, i, len;
 141         struct fq_codel_flow *flow;
 142
 143         /* Queue is full! Find the fat flow and drop packet from it.
 144          * This might sound expensive, but with 1024 flows, we scan
 145          * 4KB of memory, and we dont need to handle a complex tree
 146          * in fast path (packet queue/enqueue) with many cache misses.
 147          */
 148         for (i = 0; i < q->flows_cnt; i++) {
 149                 if (q->backlogs[i] > maxbacklog) {
 150                         maxbacklog = q->backlogs[i];
 151                         idx = i;
 152                 }
 153         }
 154         flow = &q->flows[idx];
 155         skb = dequeue_head(flow);
 156         len = qdisc_pkt_len(skb);
 157         q->backlogs[idx] -= len;
 158         sch->q.qlen--;
 159         qdisc_qstats_drop(sch);
 160         qdisc_qstats_backlog_dec(sch, skb);
 161         kfree_skb(skb);
 162         flow->dropped++;
 163         return idx;
 164 }
 165
 166 static unsigned int fq_codel_qdisc_drop(struct Qdisc *sch)
 167 {
 168         unsigned int prev_backlog;
 169
 170         prev_backlog = sch->qstats.backlog;
 171         fq_codel_drop(sch);
 172         return prev_backlog - sch->qstats.backlog;
 173 }
 174
 175 static int fq_codel_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 176 {
 177         struct fq_codel_sched_data *q = qdisc_priv(sch);
 178         unsigned int idx, prev_backlog;
 179         struct fq_codel_flow *flow;
 180         int uninitialized_var(ret);
 181
 182         idx = fq_codel_classify(skb, sch, &ret);
 183         if (idx == 0) {
 184                 if (ret & __NET_XMIT_BYPASS)
 185                         qdisc_qstats_drop(sch);
 186                 kfree_skb(skb);
 187                 return ret;
 188         }
 189         idx--;
 190
 191         codel_set_enqueue_time(skb);
 192         flow = &q->flows[idx];
 193         flow_queue_add(flow, skb);
 194         q->backlogs[idx] += qdisc_pkt_len(skb);
 195         qdisc_qstats_backlog_inc(sch, skb);
 196
 197         if (list_empty(&flow->flowchain)) {
 198                 list_add_tail(&flow->flowchain, &q->new_flows);
 199                 q->new_flow_count++;
 200                 flow->deficit = q->quantum;
 201                 flow->dropped = 0;
 202         }
 203         if (++sch->q.qlen <= sch->limit)
 204                 return NET_XMIT_SUCCESS;
 205
 206         prev_backlog = sch->qstats.backlog;
 207         q->drop_overlimit++;
 208         /* Return Congestion Notification only if we dropped a packet
 209          * from this flow.
 210          */
 211         if (fq_codel_drop(sch) == idx)
 212                 return NET_XMIT_CN;
 213
 214         /* As we dropped a packet, better let upper stack know this */
 215         qdisc_tree_reduce_backlog(sch, 1, prev_backlog - sch->qstats.backlog);
 216         return NET_XMIT_SUCCESS;
 217 }
 218
 219 /* This is the specific function called from codel_dequeue()
 220  * to dequeue a packet from queue. Note: backlog is handled in
 221  * codel, we dont need to reduce it here.
 222  */
 223 static struct sk_buff *dequeue_func(struct codel_vars *vars, void *ctx)
 224 {
 225         struct Qdisc *sch = ctx;
 226         struct fq_codel_sched_data *q = qdisc_priv(sch);
 227         struct fq_codel_flow *flow;
 228         struct sk_buff *skb = NULL;
 229
 230         flow = container_of(vars, struct fq_codel_flow, cvars);
 231         if (flow->head) {
 232                 skb = dequeue_head(flow);
 233                 q->backlogs[flow - q->flows] -= qdisc_pkt_len(skb);
 234                 sch->q.qlen--;
 235                 sch->qstats.backlog -= qdisc_pkt_len(skb);
 236         }
 237         return skb;
 238 }
 239
 240 static void drop_func(struct sk_buff *skb, void *ctx)
 241 {
 242         struct Qdisc *sch = ctx;
 243
 244         qdisc_drop(skb, sch);
 245 }
 246
 247 static struct sk_buff *fq_codel_dequeue(struct Qdisc *sch)
 248 {
 249         struct fq_codel_sched_data *q = qdisc_priv(sch);
 250         struct sk_buff *skb;
 251         struct fq_codel_flow *flow;
 252         struct list_head *head;
 253         u32 prev_drop_count, prev_ecn_mark;
 254         unsigned int prev_backlog;
 255
 256 begin:
 257         head = &q->new_flows;
 258         if (list_empty(head)) {
 259                 head = &q->old_flows;
 260                 if (list_empty(head))
 261                         return NULL;
 262         }
 263         flow = list_first_entry(head, struct fq_codel_flow, flowchain);
 264
 265         if (flow->deficit <= 0) {
 266                 flow->deficit += q->quantum;
 267                 list_move_tail(&flow->flowchain, &q->old_flows);
 268                 goto begin;
 269         }
 270
 271         prev_drop_count = q->cstats.drop_count;
 272         prev_ecn_mark = q->cstats.ecn_mark;
 273         prev_backlog = sch->qstats.backlog;
 274
 275         skb = codel_dequeue(sch, &sch->qstats.backlog, &q->cparams,
 276                             &flow->cvars, &q->cstats, qdisc_pkt_len,
 277                             codel_get_enqueue_time, drop_func, dequeue_func);
 278
 279         flow->dropped += q->cstats.drop_count - prev_drop_count;
 280         flow->dropped += q->cstats.ecn_mark - prev_ecn_mark;
 281
 282         if (!skb) {
 283                 /* force a pass through old_flows to prevent starvation */
 284                 if ((head == &q->new_flows) && !list_empty(&q->old_flows))
 285                         list_move_tail(&flow->flowchain, &q->old_flows);
 286                 else
 287                         list_del_init(&flow->flowchain);
 288                 goto begin;
 289         }
 290         qdisc_bstats_update(sch, skb);
 291         flow->deficit -= qdisc_pkt_len(skb);
 292         /* We cant call qdisc_tree_reduce_backlog() if our qlen is 0,
 293          * or HTB crashes. Defer it for next round.
 294          */
 295         if (q->cstats.drop_count && sch->q.qlen) {
 296                 qdisc_tree_reduce_backlog(sch, q->cstats.drop_count,
 297                                           q->cstats.drop_len);
 298                 q->cstats.drop_count = 0;
 299                 q->cstats.drop_len = 0;
 300         }
 301         return skb;
 302 }
 303
 304 static void fq_codel_reset(struct Qdisc *sch)
 305 {
 306         struct fq_codel_sched_data *q = qdisc_priv(sch);
 307         int i;
 308
 309         INIT_LIST_HEAD(&q->new_flows);
 310         INIT_LIST_HEAD(&q->old_flows);
 311         for (i = 0; i < q->flows_cnt; i++) {
 312                 struct fq_codel_flow *flow = q->flows + i;
 313
 314                 while (flow->head) {
 315                         struct sk_buff *skb = dequeue_head(flow);
 316
 317                         qdisc_qstats_backlog_dec(sch, skb);
 318                         kfree_skb(skb);
 319                 }
 320
 321                 INIT_LIST_HEAD(&flow->flowchain);
 322                 codel_vars_init(&flow->cvars);
 323         }
 324         memset(q->backlogs, 0, q->flows_cnt * sizeof(u32));
 325         sch->q.qlen = 0;
 326 }
 327
 328 static const struct nla_policy fq_codel_policy[TCA_FQ_CODEL_MAX + 1] = {
 329         [TCA_FQ_CODEL_TARGET]   = { .type = NLA_U32 },
 330         [TCA_FQ_CODEL_LIMIT]    = { .type = NLA_U32 },
 331         [TCA_FQ_CODEL_INTERVAL] = { .type = NLA_U32 },
 332         [TCA_FQ_CODEL_ECN]      = { .type = NLA_U32 },
 333         [TCA_FQ_CODEL_FLOWS]    = { .type = NLA_U32 },
 334         [TCA_FQ_CODEL_QUANTUM]  = { .type = NLA_U32 },
 335         [TCA_FQ_CODEL_CE_THRESHOLD] = { .type = NLA_U32 },
 336 };
 337
 338 static int fq_codel_change(struct Qdisc *sch, struct nlattr *opt)
 339 {
 340         struct fq_codel_sched_data *q = qdisc_priv(sch);
 341         struct nlattr *tb[TCA_FQ_CODEL_MAX + 1];
 342         int err;
 343
 344         if (!opt)
 345                 return -EINVAL;
 346
 347         err = nla_parse_nested(tb, TCA_FQ_CODEL_MAX, opt, fq_codel_policy);
 348         if (err < 0)
 349                 return err;
 350         if (tb[TCA_FQ_CODEL_FLOWS]) {
 351                 if (q->flows)
 352                         return -EINVAL;
 353                 q->flows_cnt = nla_get_u32(tb[TCA_FQ_CODEL_FLOWS]);
 354                 if (!q->flows_cnt ||
 355                     q->flows_cnt > 65536)
 356                         return -EINVAL;
 357         }
 358         sch_tree_lock(sch);
 359
 360         if (tb[TCA_FQ_CODEL_TARGET]) {
 361                 u64 target = nla_get_u32(tb[TCA_FQ_CODEL_TARGET]);
 362
 363                 q->cparams.target = (target * NSEC_PER_USEC) >> CODEL_SHIFT;
 364         }
 365
 366         if (tb[TCA_FQ_CODEL_CE_THRESHOLD]) {
 367                 u64 val = nla_get_u32(tb[TCA_FQ_CODEL_CE_THRESHOLD]);
 368
 369                 q->cparams.ce_threshold = (val * NSEC_PER_USEC) >> CODEL_SHIFT;
 370         }
 371
 372         if (tb[TCA_FQ_CODEL_INTERVAL]) {
 373                 u64 interval = nla_get_u32(tb[TCA_FQ_CODEL_INTERVAL]);
 374
 375                 q->cparams.interval = (interval * NSEC_PER_USEC) >> CODEL_SHIFT;
 376         }
 377
 378         if (tb[TCA_FQ_CODEL_LIMIT])
 379                 sch->limit = nla_get_u32(tb[TCA_FQ_CODEL_LIMIT]);
 380
 381         if (tb[TCA_FQ_CODEL_ECN])
 382                 q->cparams.ecn = !!nla_get_u32(tb[TCA_FQ_CODEL_ECN]);
 383
 384         if (tb[TCA_FQ_CODEL_QUANTUM])
 385                 q->quantum = max(256U, nla_get_u32(tb[TCA_FQ_CODEL_QUANTUM]));
 386
 387         while (sch->q.qlen > sch->limit) {
 388                 struct sk_buff *skb = fq_codel_dequeue(sch);
 389
 390                 q->cstats.drop_len += qdisc_pkt_len(skb);
 391                 kfree_skb(skb);
 392                 q->cstats.drop_count++;
 393         }
 394         qdisc_tree_reduce_backlog(sch, q->cstats.drop_count, q->cstats.drop_len);
 395         q->cstats.drop_count = 0;
 396         q->cstats.drop_len = 0;
 397
 398         sch_tree_unlock(sch);
 399         return 0;
 400 }
 401
 402 static void *fq_codel_zalloc(size_t sz)
 403 {
 404         void *ptr = kzalloc(sz, GFP_KERNEL | __GFP_NOWARN);
 405
 406         if (!ptr)
 407                 ptr = vzalloc(sz);
 408         return ptr;
 409 }
 410
 411 static void fq_codel_free(void *addr)
 412 {
 413         kvfree(addr);
 414 }
 415
 416 static void fq_codel_destroy(struct Qdisc *sch)
 417 {
 418         struct fq_codel_sched_data *q = qdisc_priv(sch);
 419
 420         tcf_destroy_chain(&q->filter_list);
 421         fq_codel_free(q->backlogs);
 422         fq_codel_free(q->flows);
 423 }
 424
 425 static int fq_codel_init(struct Qdisc *sch, struct nlattr *opt)
 426 {
 427         struct fq_codel_sched_data *q = qdisc_priv(sch);
 428         int i;
 429
 430         sch->limit = 10*1024;
 431         q->flows_cnt = 1024;
 432         q->quantum = psched_mtu(qdisc_dev(sch));
 433         q->perturbation = prandom_u32();
 434         INIT_LIST_HEAD(&q->new_flows);
 435         INIT_LIST_HEAD(&q->old_flows);
 436         codel_params_init(&q->cparams);
 437         codel_stats_init(&q->cstats);
 438         q->cparams.ecn = true;
 439         q->cparams.mtu = psched_mtu(qdisc_dev(sch));
 440
 441         if (opt) {
 442                 int err = fq_codel_change(sch, opt);
 443                 if (err)
 444                         return err;
 445         }
 446
 447         if (!q->flows) {
 448                 q->flows = fq_codel_zalloc(q->flows_cnt *
 449                                            sizeof(struct fq_codel_flow));
 450                 if (!q->flows)
 451                         return -ENOMEM;
 452                 q->backlogs = fq_codel_zalloc(q->flows_cnt * sizeof(u32));
 453                 if (!q->backlogs) {
 454                         fq_codel_free(q->flows);
 455                         return -ENOMEM;
 456                 }
 457                 for (i = 0; i < q->flows_cnt; i++) {
 458                         struct fq_codel_flow *flow = q->flows + i;
 459
 460                         INIT_LIST_HEAD(&flow->flowchain);
 461                         codel_vars_init(&flow->cvars);
 462                 }
 463         }
 464         if (sch->limit >= 1)
 465                 sch->flags |= TCQ_F_CAN_BYPASS;
 466         else
 467                 sch->flags &= ~TCQ_F_CAN_BYPASS;
 468         return 0;
 469 }
 470
 471 static int fq_codel_dump(struct Qdisc *sch, struct sk_buff *skb)
 472 {
 473         struct fq_codel_sched_data *q = qdisc_priv(sch);
 474         struct nlattr *opts;
 475
 476         opts = nla_nest_start(skb, TCA_OPTIONS);
 477         if (opts == NULL)
 478                 goto nla_put_failure;
 479
 480         if (nla_put_u32(skb, TCA_FQ_CODEL_TARGET,
 481                         codel_time_to_us(q->cparams.target)) ||
 482             nla_put_u32(skb, TCA_FQ_CODEL_LIMIT,
 483                         sch->limit) ||
 484             nla_put_u32(skb, TCA_FQ_CODEL_INTERVAL,
 485                         codel_time_to_us(q->cparams.interval)) ||
 486             nla_put_u32(skb, TCA_FQ_CODEL_ECN,
 487                         q->cparams.ecn) ||
 488             nla_put_u32(skb, TCA_FQ_CODEL_QUANTUM,
 489                         q->quantum) ||
 490             nla_put_u32(skb, TCA_FQ_CODEL_FLOWS,
 491                         q->flows_cnt))
 492                 goto nla_put_failure;
 493
 494         if (q->cparams.ce_threshold != CODEL_DISABLED_THRESHOLD &&
 495             nla_put_u32(skb, TCA_FQ_CODEL_CE_THRESHOLD,
 496                         codel_time_to_us(q->cparams.ce_threshold)))
 497                 goto nla_put_failure;
 498
 499         return nla_nest_end(skb, opts);
 500
 501 nla_put_failure:
 502         return -1;
 503 }
 504
 505 static int fq_codel_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
 506 {
 507         struct fq_codel_sched_data *q = qdisc_priv(sch);
 508         struct tc_fq_codel_xstats st = {
 509                 .type                           = TCA_FQ_CODEL_XSTATS_QDISC,
 510         };
 511         struct list_head *pos;
 512
 513         st.qdisc_stats.maxpacket = q->cstats.maxpacket;
 514         st.qdisc_stats.drop_overlimit = q->drop_overlimit;
 515         st.qdisc_stats.ecn_mark = q->cstats.ecn_mark;
 516         st.qdisc_stats.new_flow_count = q->new_flow_count;
 517         st.qdisc_stats.ce_mark = q->cstats.ce_mark;
 518
 519         list_for_each(pos, &q->new_flows)
 520                 st.qdisc_stats.new_flows_len++;
 521
 522         list_for_each(pos, &q->old_flows)
 523                 st.qdisc_stats.old_flows_len++;
 524
 525         return gnet_stats_copy_app(d, &st, sizeof(st));
 526 }
 527
 528 static struct Qdisc *fq_codel_leaf(struct Qdisc *sch, unsigned long arg)
 529 {
 530         return NULL;
 531 }
 532
 533 static unsigned long fq_codel_get(struct Qdisc *sch, u32 classid)
 534 {
 535         return 0;
 536 }
 537
 538 static unsigned long fq_codel_bind(struct Qdisc *sch, unsigned long parent,
 539                               u32 classid)
 540 {
 541         /* we cannot bypass queue discipline anymore */
 542         sch->flags &= ~TCQ_F_CAN_BYPASS;
 543         return 0;
 544 }
 545
 546 static void fq_codel_put(struct Qdisc *q, unsigned long cl)
 547 {
 548 }
 549
 550 static struct tcf_proto __rcu **fq_codel_find_tcf(struct Qdisc *sch,
 551                                                   unsigned long cl)
 552 {
 553         struct fq_codel_sched_data *q = qdisc_priv(sch);
 554
 555         if (cl)
 556                 return NULL;
 557         return &q->filter_list;
 558 }
 559
 560 static int fq_codel_dump_class(struct Qdisc *sch, unsigned long cl,
 561                           struct sk_buff *skb, struct tcmsg *tcm)
 562 {
 563         tcm->tcm_handle |= TC_H_MIN(cl);
 564         return 0;
 565 }
 566
 567 static int fq_codel_dump_class_stats(struct Qdisc *sch, unsigned long cl,
 568                                      struct gnet_dump *d)
 569 {
 570         struct fq_codel_sched_data *q = qdisc_priv(sch);
 571         u32 idx = cl - 1;
 572         struct gnet_stats_queue qs = { 0 };
 573         struct tc_fq_codel_xstats xstats;
 574
 575         if (idx < q->flows_cnt) {
 576                 const struct fq_codel_flow *flow = &q->flows[idx];
 577                 const struct sk_buff *skb = flow->head;
 578
 579                 memset(&xstats, 0, sizeof(xstats));
 580                 xstats.type = TCA_FQ_CODEL_XSTATS_CLASS;
 581                 xstats.class_stats.deficit = flow->deficit;
 582                 xstats.class_stats.ldelay =
 583                         codel_time_to_us(flow->cvars.ldelay);
 584                 xstats.class_stats.count = flow->cvars.count;
 585                 xstats.class_stats.lastcount = flow->cvars.lastcount;
 586                 xstats.class_stats.dropping = flow->cvars.dropping;
 587                 if (flow->cvars.dropping) {
 588                         codel_tdiff_t delta = flow->cvars.drop_next -
 589                                               codel_get_time();
 590
 591                         xstats.class_stats.drop_next = (delta >= 0) ?
 592                                 codel_time_to_us(delta) :
 593                                 -codel_time_to_us(-delta);
 594                 }
 595                 while (skb) {
 596                         qs.qlen++;
 597                         skb = skb->next;
 598                 }
 599                 qs.backlog = q->backlogs[idx];
 600                 qs.drops = flow->dropped;
 601         }
 602         if (gnet_stats_copy_queue(d, NULL, &qs, 0) < 0)
 603                 return -1;
 604         if (idx < q->flows_cnt)
 605                 return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
 606         return 0;
 607 }
 608
 609 static void fq_codel_walk(struct Qdisc *sch, struct qdisc_walker *arg)
 610 {
 611         struct fq_codel_sched_data *q = qdisc_priv(sch);
 612         unsigned int i;
 613
 614         if (arg->stop)
 615                 return;
 616
 617         for (i = 0; i < q->flows_cnt; i++) {
 618                 if (list_empty(&q->flows[i].flowchain) ||
 619                     arg->count < arg->skip) {
 620                         arg->count++;
 621                         continue;
 622                 }
 623                 if (arg->fn(sch, i + 1, arg) < 0) {
 624                         arg->stop = 1;
 625                         break;
 626                 }
 627                 arg->count++;
 628         }
 629 }
 630
 631 static const struct Qdisc_class_ops fq_codel_class_ops = {
 632         .leaf           =       fq_codel_leaf,
 633         .get            =       fq_codel_get,
 634         .put            =       fq_codel_put,
 635         .tcf_chain      =       fq_codel_find_tcf,
 636         .bind_tcf       =       fq_codel_bind,
 637         .unbind_tcf     =       fq_codel_put,
 638         .dump           =       fq_codel_dump_class,
 639         .dump_stats     =       fq_codel_dump_class_stats,
 640         .walk           =       fq_codel_walk,
 641 };
 642
 643 static struct Qdisc_ops fq_codel_qdisc_ops __read_mostly = {
 644         .cl_ops         =       &fq_codel_class_ops,
 645         .id             =       "fq_codel",
 646         .priv_size      =       sizeof(struct fq_codel_sched_data),
 647         .enqueue        =       fq_codel_enqueue,
 648         .dequeue        =       fq_codel_dequeue,
 649         .peek           =       qdisc_peek_dequeued,
 650         .drop           =       fq_codel_qdisc_drop,
 651         .init           =       fq_codel_init,
 652         .reset          =       fq_codel_reset,
 653         .destroy        =       fq_codel_destroy,
 654         .change         =       fq_codel_change,
 655         .dump           =       fq_codel_dump,
 656         .dump_stats =   fq_codel_dump_stats,
 657         .owner          =       THIS_MODULE,
 658 };
 659
 660 static int __init fq_codel_module_init(void)
 661 {
 662         return register_qdisc(&fq_codel_qdisc_ops);
 663 }
 664
 665 static void __exit fq_codel_module_exit(void)
 666 {
 667         unregister_qdisc(&fq_codel_qdisc_ops);
 668 }
 669
 670 module_init(fq_codel_module_init)
 671 module_exit(fq_codel_module_exit)
 672 MODULE_AUTHOR("Eric Dumazet");
 673 MODULE_LICENSE("GPL");