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 #include <net/codel_impl.h>
  28 #include <net/codel_qdisc.h>
  29
  30 /*      Fair Queue CoDel.
  31  *
  32  * Principles :
  33  * Packets are classified (internal classifier or external) on flows.
  34  * This is a Stochastic model (as we use a hash, several flows
  35  *                             might be hashed on same slot)
  36  * Each flow has a CoDel managed queue.
  37  * Flows are linked onto two (Round Robin) lists,
  38  * so that new flows have priority on old ones.
  39  *
  40  * For a given flow, packets are not reordered (CoDel uses a FIFO)
  41  * head drops only.
  42  * ECN capability is on by default.
  43  * Low memory footprint (64 bytes per flow)
  44  */
  45
  46 struct fq_codel_flow {
  47         struct sk_buff    *head;
  48         struct sk_buff    *tail;
  49         struct list_head  flowchain;
  50         int               deficit;
  51         u32               dropped; /* number of drops (or ECN marks) on this flow */
  52         struct codel_vars cvars;
  53 }; /* please try to keep this structure <= 64 bytes */
  54
  55 struct fq_codel_sched_data {
  56         struct tcf_proto __rcu *filter_list; /* optional external classifier */
  57         struct fq_codel_flow *flows;    /* Flows table [flows_cnt] */
  58         u32             *backlogs;      /* backlog table [flows_cnt] */
  59         u32             flows_cnt;      /* number of flows */
  60         u32             perturbation;   /* hash perturbation */
  61         u32             quantum;        /* psched_mtu(qdisc_dev(sch)); */
  62         u32             drop_batch_size;
  63         u32             memory_limit;
  64         struct codel_params cparams;
  65         struct codel_stats cstats;
  66         u32             memory_usage;
  67         u32             drop_overmemory;
  68         u32             drop_overlimit;
  69         u32             new_flow_count;
  70
  71         struct list_head new_flows;     /* list of new flows */
  72         struct list_head old_flows;     /* list of old flows */
  73 };
  74
  75 static unsigned int fq_codel_hash(const struct fq_codel_sched_data *q,
  76                                   struct sk_buff *skb)
  77 {
  78         u32 hash = skb_get_hash_perturb(skb, q->perturbation);
  79
  80         return reciprocal_scale(hash, q->flows_cnt);
  81 }
  82
  83 static unsigned int fq_codel_classify(struct sk_buff *skb, struct Qdisc *sch,
  84                                       int *qerr)
  85 {
  86         struct fq_codel_sched_data *q = qdisc_priv(sch);
  87         struct tcf_proto *filter;
  88         struct tcf_result res;
  89         int result;
  90
  91         if (TC_H_MAJ(skb->priority) == sch->handle &&
  92             TC_H_MIN(skb->priority) > 0 &&
  93             TC_H_MIN(skb->priority) <= q->flows_cnt)
  94                 return TC_H_MIN(skb->priority);
  95
  96         filter = rcu_dereference_bh(q->filter_list);
  97         if (!filter)
  98                 return fq_codel_hash(q, skb) + 1;
  99
 100         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
 101         result = tc_classify(skb, filter, &res, false);
 102         if (result >= 0) {
 103 #ifdef CONFIG_NET_CLS_ACT
 104                 switch (result) {
 105                 case TC_ACT_STOLEN:
 106                 case TC_ACT_QUEUED:
 107                         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
 108                 case TC_ACT_SHOT:
 109                         return 0;
 110                 }
 111 #endif
 112                 if (TC_H_MIN(res.classid) <= q->flows_cnt)
 113                         return TC_H_MIN(res.classid);
 114         }
 115         return 0;
 116 }
 117
 118 /* helper functions : might be changed when/if skb use a standard list_head */
 119
 120 /* remove one skb from head of slot queue */
 121 static inline struct sk_buff *dequeue_head(struct fq_codel_flow *flow)
 122 {
 123         struct sk_buff *skb = flow->head;
 124
 125         flow->head = skb->next;
 126         skb->next = NULL;
 127         return skb;
 128 }
 129
 130 /* add skb to flow queue (tail add) */
 131 static inline void flow_queue_add(struct fq_codel_flow *flow,
 132                                   struct sk_buff *skb)
 133 {
 134         if (flow->head == NULL)
 135                 flow->head = skb;
 136         else
 137                 flow->tail->next = skb;
 138         flow->tail = skb;
 139         skb->next = NULL;
 140 }
 141
 142 static unsigned int fq_codel_drop(struct Qdisc *sch, unsigned int max_packets,
 143                                   struct sk_buff **to_free)
 144 {
 145         struct fq_codel_sched_data *q = qdisc_priv(sch);
 146         struct sk_buff *skb;
 147         unsigned int maxbacklog = 0, idx = 0, i, len;
 148         struct fq_codel_flow *flow;
 149         unsigned int threshold;
 150         unsigned int mem = 0;
 151
 152         /* Queue is full! Find the fat flow and drop packet(s) from it.
 153          * This might sound expensive, but with 1024 flows, we scan
 154          * 4KB of memory, and we dont need to handle a complex tree
 155          * in fast path (packet queue/enqueue) with many cache misses.
 156          * In stress mode, we'll try to drop 64 packets from the flow,
 157          * amortizing this linear lookup to one cache line per drop.
 158          */
 159         for (i = 0; i < q->flows_cnt; i++) {
 160                 if (q->backlogs[i] > maxbacklog) {
 161                         maxbacklog = q->backlogs[i];
 162                         idx = i;
 163                 }
 164         }
 165
 166         /* Our goal is to drop half of this fat flow backlog */
 167         threshold = maxbacklog >> 1;
 168
 169         flow = &q->flows[idx];
 170         len = 0;
 171         i = 0;
 172         do {
 173                 skb = dequeue_head(flow);
 174                 len += qdisc_pkt_len(skb);
 175                 mem += get_codel_cb(skb)->mem_usage;
 176                 __qdisc_drop(skb, to_free);
 177         } while (++i < max_packets && len < threshold);
 178
 179         flow->dropped += i;
 180         q->backlogs[idx] -= len;
 181         q->memory_usage -= mem;
 182         sch->qstats.drops += i;
 183         sch->qstats.backlog -= len;
 184         sch->q.qlen -= i;
 185         return idx;
 186 }
 187
 188 static int fq_codel_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 189                             struct sk_buff **to_free)
 190 {
 191         struct fq_codel_sched_data *q = qdisc_priv(sch);
 192         unsigned int idx, prev_backlog, prev_qlen;
 193         struct fq_codel_flow *flow;
 194         int uninitialized_var(ret);
 195         unsigned int pkt_len;
 196         bool memory_limited;
 197
 198         idx = fq_codel_classify(skb, sch, &ret);
 199         if (idx == 0) {
 200                 if (ret & __NET_XMIT_BYPASS)
 201                         qdisc_qstats_drop(sch);
 202                 __qdisc_drop(skb, to_free);
 203                 return ret;
 204         }
 205         idx--;
 206
 207         codel_set_enqueue_time(skb);
 208         flow = &q->flows[idx];
 209         flow_queue_add(flow, skb);
 210         q->backlogs[idx] += qdisc_pkt_len(skb);
 211         qdisc_qstats_backlog_inc(sch, skb);
 212
 213         if (list_empty(&flow->flowchain)) {
 214                 list_add_tail(&flow->flowchain, &q->new_flows);
 215                 q->new_flow_count++;
 216                 flow->deficit = q->quantum;
 217                 flow->dropped = 0;
 218         }
 219         get_codel_cb(skb)->mem_usage = skb->truesize;
 220         q->memory_usage += get_codel_cb(skb)->mem_usage;
 221         memory_limited = q->memory_usage > q->memory_limit;
 222         if (++sch->q.qlen <= sch->limit && !memory_limited)
 223                 return NET_XMIT_SUCCESS;
 224
 225         prev_backlog = sch->qstats.backlog;
 226         prev_qlen = sch->q.qlen;
 227
 228         /* save this packet length as it might be dropped by fq_codel_drop() */
 229         pkt_len = qdisc_pkt_len(skb);
 230         /* fq_codel_drop() is quite expensive, as it performs a linear search
 231          * in q->backlogs[] to find a fat flow.
 232          * So instead of dropping a single packet, drop half of its backlog
 233          * with a 64 packets limit to not add a too big cpu spike here.
 234          */
 235         ret = fq_codel_drop(sch, q->drop_batch_size, to_free);
 236
 237         prev_qlen -= sch->q.qlen;
 238         prev_backlog -= sch->qstats.backlog;
 239         q->drop_overlimit += prev_qlen;
 240         if (memory_limited)
 241                 q->drop_overmemory += prev_qlen;
 242
 243         /* As we dropped packet(s), better let upper stack know this.
 244          * If we dropped a packet for this flow, return NET_XMIT_CN,
 245          * but in this case, our parents wont increase their backlogs.
 246          */
 247         if (ret == idx) {
 248                 qdisc_tree_reduce_backlog(sch, prev_qlen - 1,
 249                                           prev_backlog - pkt_len);
 250                 return NET_XMIT_CN;
 251         }
 252         qdisc_tree_reduce_backlog(sch, prev_qlen, prev_backlog);
 253         return NET_XMIT_SUCCESS;
 254 }
 255
 256 /* This is the specific function called from codel_dequeue()
 257  * to dequeue a packet from queue. Note: backlog is handled in
 258  * codel, we dont need to reduce it here.
 259  */
 260 static struct sk_buff *dequeue_func(struct codel_vars *vars, void *ctx)
 261 {
 262         struct Qdisc *sch = ctx;
 263         struct fq_codel_sched_data *q = qdisc_priv(sch);
 264         struct fq_codel_flow *flow;
 265         struct sk_buff *skb = NULL;
 266
 267         flow = container_of(vars, struct fq_codel_flow, cvars);
 268         if (flow->head) {
 269                 skb = dequeue_head(flow);
 270                 q->backlogs[flow - q->flows] -= qdisc_pkt_len(skb);
 271                 q->memory_usage -= get_codel_cb(skb)->mem_usage;
 272                 sch->q.qlen--;
 273                 sch->qstats.backlog -= qdisc_pkt_len(skb);
 274         }
 275         return skb;
 276 }
 277
 278 static void drop_func(struct sk_buff *skb, void *ctx)
 279 {
 280         struct Qdisc *sch = ctx;
 281
 282         kfree_skb(skb);
 283         qdisc_qstats_drop(sch);
 284 }
 285
 286 static struct sk_buff *fq_codel_dequeue(struct Qdisc *sch)
 287 {
 288         struct fq_codel_sched_data *q = qdisc_priv(sch);
 289         struct sk_buff *skb;
 290         struct fq_codel_flow *flow;
 291         struct list_head *head;
 292         u32 prev_drop_count, prev_ecn_mark;
 293         unsigned int prev_backlog;
 294
 295 begin:
 296         head = &q->new_flows;
 297         if (list_empty(head)) {
 298                 head = &q->old_flows;
 299                 if (list_empty(head))
 300                         return NULL;
 301         }
 302         flow = list_first_entry(head, struct fq_codel_flow, flowchain);
 303
 304         if (flow->deficit <= 0) {
 305                 flow->deficit += q->quantum;
 306                 list_move_tail(&flow->flowchain, &q->old_flows);
 307                 goto begin;
 308         }
 309
 310         prev_drop_count = q->cstats.drop_count;
 311         prev_ecn_mark = q->cstats.ecn_mark;
 312         prev_backlog = sch->qstats.backlog;
 313
 314         skb = codel_dequeue(sch, &sch->qstats.backlog, &q->cparams,
 315                             &flow->cvars, &q->cstats, qdisc_pkt_len,
 316                             codel_get_enqueue_time, drop_func, dequeue_func);
 317
 318         flow->dropped += q->cstats.drop_count - prev_drop_count;
 319         flow->dropped += q->cstats.ecn_mark - prev_ecn_mark;
 320
 321         if (!skb) {
 322                 /* force a pass through old_flows to prevent starvation */
 323                 if ((head == &q->new_flows) && !list_empty(&q->old_flows))
 324                         list_move_tail(&flow->flowchain, &q->old_flows);
 325                 else
 326                         list_del_init(&flow->flowchain);
 327                 goto begin;
 328         }
 329         qdisc_bstats_update(sch, skb);
 330         flow->deficit -= qdisc_pkt_len(skb);
 331         /* We cant call qdisc_tree_reduce_backlog() if our qlen is 0,
 332          * or HTB crashes. Defer it for next round.
 333          */
 334         if (q->cstats.drop_count && sch->q.qlen) {
 335                 qdisc_tree_reduce_backlog(sch, q->cstats.drop_count,
 336                                           q->cstats.drop_len);
 337                 q->cstats.drop_count = 0;
 338                 q->cstats.drop_len = 0;
 339         }
 340         return skb;
 341 }
 342
 343 static void fq_codel_flow_purge(struct fq_codel_flow *flow)
 344 {
 345         rtnl_kfree_skbs(flow->head, flow->tail);
 346         flow->head = NULL;
 347 }
 348
 349 static void fq_codel_reset(struct Qdisc *sch)
 350 {
 351         struct fq_codel_sched_data *q = qdisc_priv(sch);
 352         int i;
 353
 354         INIT_LIST_HEAD(&q->new_flows);
 355         INIT_LIST_HEAD(&q->old_flows);
 356         for (i = 0; i < q->flows_cnt; i++) {
 357                 struct fq_codel_flow *flow = q->flows + i;
 358
 359                 fq_codel_flow_purge(flow);
 360                 INIT_LIST_HEAD(&flow->flowchain);
 361                 codel_vars_init(&flow->cvars);
 362         }
 363         memset(q->backlogs, 0, q->flows_cnt * sizeof(u32));
 364         sch->q.qlen = 0;
 365         sch->qstats.backlog = 0;
 366         q->memory_usage = 0;
 367 }
 368
 369 static const struct nla_policy fq_codel_policy[TCA_FQ_CODEL_MAX + 1] = {
 370         [TCA_FQ_CODEL_TARGET]   = { .type = NLA_U32 },
 371         [TCA_FQ_CODEL_LIMIT]    = { .type = NLA_U32 },
 372         [TCA_FQ_CODEL_INTERVAL] = { .type = NLA_U32 },
 373         [TCA_FQ_CODEL_ECN]      = { .type = NLA_U32 },
 374         [TCA_FQ_CODEL_FLOWS]    = { .type = NLA_U32 },
 375         [TCA_FQ_CODEL_QUANTUM]  = { .type = NLA_U32 },
 376         [TCA_FQ_CODEL_CE_THRESHOLD] = { .type = NLA_U32 },
 377         [TCA_FQ_CODEL_DROP_BATCH_SIZE] = { .type = NLA_U32 },
 378         [TCA_FQ_CODEL_MEMORY_LIMIT] = { .type = NLA_U32 },
 379 };
 380
 381 static int fq_codel_change(struct Qdisc *sch, struct nlattr *opt)
 382 {
 383         struct fq_codel_sched_data *q = qdisc_priv(sch);
 384         struct nlattr *tb[TCA_FQ_CODEL_MAX + 1];
 385         int err;
 386
 387         if (!opt)
 388                 return -EINVAL;
 389
 390         err = nla_parse_nested(tb, TCA_FQ_CODEL_MAX, opt, fq_codel_policy);
 391         if (err < 0)
 392                 return err;
 393         if (tb[TCA_FQ_CODEL_FLOWS]) {
 394                 if (q->flows)
 395                         return -EINVAL;
 396                 q->flows_cnt = nla_get_u32(tb[TCA_FQ_CODEL_FLOWS]);
 397                 if (!q->flows_cnt ||
 398                     q->flows_cnt > 65536)
 399                         return -EINVAL;
 400         }
 401         sch_tree_lock(sch);
 402
 403         if (tb[TCA_FQ_CODEL_TARGET]) {
 404                 u64 target = nla_get_u32(tb[TCA_FQ_CODEL_TARGET]);
 405
 406                 q->cparams.target = (target * NSEC_PER_USEC) >> CODEL_SHIFT;
 407         }
 408
 409         if (tb[TCA_FQ_CODEL_CE_THRESHOLD]) {
 410                 u64 val = nla_get_u32(tb[TCA_FQ_CODEL_CE_THRESHOLD]);
 411
 412                 q->cparams.ce_threshold = (val * NSEC_PER_USEC) >> CODEL_SHIFT;
 413         }
 414
 415         if (tb[TCA_FQ_CODEL_INTERVAL]) {
 416                 u64 interval = nla_get_u32(tb[TCA_FQ_CODEL_INTERVAL]);
 417
 418                 q->cparams.interval = (interval * NSEC_PER_USEC) >> CODEL_SHIFT;
 419         }
 420
 421         if (tb[TCA_FQ_CODEL_LIMIT])
 422                 sch->limit = nla_get_u32(tb[TCA_FQ_CODEL_LIMIT]);
 423
 424         if (tb[TCA_FQ_CODEL_ECN])
 425                 q->cparams.ecn = !!nla_get_u32(tb[TCA_FQ_CODEL_ECN]);
 426
 427         if (tb[TCA_FQ_CODEL_QUANTUM])
 428                 q->quantum = max(256U, nla_get_u32(tb[TCA_FQ_CODEL_QUANTUM]));
 429
 430         if (tb[TCA_FQ_CODEL_DROP_BATCH_SIZE])
 431                 q->drop_batch_size = min(1U, nla_get_u32(tb[TCA_FQ_CODEL_DROP_BATCH_SIZE]));
 432
 433         if (tb[TCA_FQ_CODEL_MEMORY_LIMIT])
 434                 q->memory_limit = min(1U << 31, nla_get_u32(tb[TCA_FQ_CODEL_MEMORY_LIMIT]));
 435
 436         while (sch->q.qlen > sch->limit ||
 437                q->memory_usage > q->memory_limit) {
 438                 struct sk_buff *skb = fq_codel_dequeue(sch);
 439
 440                 q->cstats.drop_len += qdisc_pkt_len(skb);
 441                 rtnl_kfree_skbs(skb, skb);
 442                 q->cstats.drop_count++;
 443         }
 444         qdisc_tree_reduce_backlog(sch, q->cstats.drop_count, q->cstats.drop_len);
 445         q->cstats.drop_count = 0;
 446         q->cstats.drop_len = 0;
 447
 448         sch_tree_unlock(sch);
 449         return 0;
 450 }
 451
 452 static void *fq_codel_zalloc(size_t sz)
 453 {
 454         void *ptr = kzalloc(sz, GFP_KERNEL | __GFP_NOWARN);
 455
 456         if (!ptr)
 457                 ptr = vzalloc(sz);
 458         return ptr;
 459 }
 460
 461 static void fq_codel_free(void *addr)
 462 {
 463         kvfree(addr);
 464 }
 465
 466 static void fq_codel_destroy(struct Qdisc *sch)
 467 {
 468         struct fq_codel_sched_data *q = qdisc_priv(sch);
 469
 470         tcf_destroy_chain(&q->filter_list);
 471         fq_codel_free(q->backlogs);
 472         fq_codel_free(q->flows);
 473 }
 474
 475 static int fq_codel_init(struct Qdisc *sch, struct nlattr *opt)
 476 {
 477         struct fq_codel_sched_data *q = qdisc_priv(sch);
 478         int i;
 479
 480         sch->limit = 10*1024;
 481         q->flows_cnt = 1024;
 482         q->memory_limit = 32 << 20; /* 32 MBytes */
 483         q->drop_batch_size = 64;
 484         q->quantum = psched_mtu(qdisc_dev(sch));
 485         q->perturbation = prandom_u32();
 486         INIT_LIST_HEAD(&q->new_flows);
 487         INIT_LIST_HEAD(&q->old_flows);
 488         codel_params_init(&q->cparams);
 489         codel_stats_init(&q->cstats);
 490         q->cparams.ecn = true;
 491         q->cparams.mtu = psched_mtu(qdisc_dev(sch));
 492
 493         if (opt) {
 494                 int err = fq_codel_change(sch, opt);
 495                 if (err)
 496                         return err;
 497         }
 498
 499         if (!q->flows) {
 500                 q->flows = fq_codel_zalloc(q->flows_cnt *
 501                                            sizeof(struct fq_codel_flow));
 502                 if (!q->flows)
 503                         return -ENOMEM;
 504                 q->backlogs = fq_codel_zalloc(q->flows_cnt * sizeof(u32));
 505                 if (!q->backlogs) {
 506                         fq_codel_free(q->flows);
 507                         return -ENOMEM;
 508                 }
 509                 for (i = 0; i < q->flows_cnt; i++) {
 510                         struct fq_codel_flow *flow = q->flows + i;
 511
 512                         INIT_LIST_HEAD(&flow->flowchain);
 513                         codel_vars_init(&flow->cvars);
 514                 }
 515         }
 516         if (sch->limit >= 1)
 517                 sch->flags |= TCQ_F_CAN_BYPASS;
 518         else
 519                 sch->flags &= ~TCQ_F_CAN_BYPASS;
 520         return 0;
 521 }
 522
 523 static int fq_codel_dump(struct Qdisc *sch, struct sk_buff *skb)
 524 {
 525         struct fq_codel_sched_data *q = qdisc_priv(sch);
 526         struct nlattr *opts;
 527
 528         opts = nla_nest_start(skb, TCA_OPTIONS);
 529         if (opts == NULL)
 530                 goto nla_put_failure;
 531
 532         if (nla_put_u32(skb, TCA_FQ_CODEL_TARGET,
 533                         codel_time_to_us(q->cparams.target)) ||
 534             nla_put_u32(skb, TCA_FQ_CODEL_LIMIT,
 535                         sch->limit) ||
 536             nla_put_u32(skb, TCA_FQ_CODEL_INTERVAL,
 537                         codel_time_to_us(q->cparams.interval)) ||
 538             nla_put_u32(skb, TCA_FQ_CODEL_ECN,
 539                         q->cparams.ecn) ||
 540             nla_put_u32(skb, TCA_FQ_CODEL_QUANTUM,
 541                         q->quantum) ||
 542             nla_put_u32(skb, TCA_FQ_CODEL_DROP_BATCH_SIZE,
 543                         q->drop_batch_size) ||
 544             nla_put_u32(skb, TCA_FQ_CODEL_MEMORY_LIMIT,
 545                         q->memory_limit) ||
 546             nla_put_u32(skb, TCA_FQ_CODEL_FLOWS,
 547                         q->flows_cnt))
 548                 goto nla_put_failure;
 549
 550         if (q->cparams.ce_threshold != CODEL_DISABLED_THRESHOLD &&
 551             nla_put_u32(skb, TCA_FQ_CODEL_CE_THRESHOLD,
 552                         codel_time_to_us(q->cparams.ce_threshold)))
 553                 goto nla_put_failure;
 554
 555         return nla_nest_end(skb, opts);
 556
 557 nla_put_failure:
 558         return -1;
 559 }
 560
 561 static int fq_codel_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
 562 {
 563         struct fq_codel_sched_data *q = qdisc_priv(sch);
 564         struct tc_fq_codel_xstats st = {
 565                 .type                           = TCA_FQ_CODEL_XSTATS_QDISC,
 566         };
 567         struct list_head *pos;
 568
 569         st.qdisc_stats.maxpacket = q->cstats.maxpacket;
 570         st.qdisc_stats.drop_overlimit = q->drop_overlimit;
 571         st.qdisc_stats.ecn_mark = q->cstats.ecn_mark;
 572         st.qdisc_stats.new_flow_count = q->new_flow_count;
 573         st.qdisc_stats.ce_mark = q->cstats.ce_mark;
 574         st.qdisc_stats.memory_usage  = q->memory_usage;
 575         st.qdisc_stats.drop_overmemory = q->drop_overmemory;
 576
 577         sch_tree_lock(sch);
 578         list_for_each(pos, &q->new_flows)
 579                 st.qdisc_stats.new_flows_len++;
 580
 581         list_for_each(pos, &q->old_flows)
 582                 st.qdisc_stats.old_flows_len++;
 583         sch_tree_unlock(sch);
 584
 585         return gnet_stats_copy_app(d, &st, sizeof(st));
 586 }
 587
 588 static struct Qdisc *fq_codel_leaf(struct Qdisc *sch, unsigned long arg)
 589 {
 590         return NULL;
 591 }
 592
 593 static unsigned long fq_codel_get(struct Qdisc *sch, u32 classid)
 594 {
 595         return 0;
 596 }
 597
 598 static unsigned long fq_codel_bind(struct Qdisc *sch, unsigned long parent,
 599                               u32 classid)
 600 {
 601         /* we cannot bypass queue discipline anymore */
 602         sch->flags &= ~TCQ_F_CAN_BYPASS;
 603         return 0;
 604 }
 605
 606 static void fq_codel_put(struct Qdisc *q, unsigned long cl)
 607 {
 608 }
 609
 610 static struct tcf_proto __rcu **fq_codel_find_tcf(struct Qdisc *sch,
 611                                                   unsigned long cl)
 612 {
 613         struct fq_codel_sched_data *q = qdisc_priv(sch);
 614
 615         if (cl)
 616                 return NULL;
 617         return &q->filter_list;
 618 }
 619
 620 static int fq_codel_dump_class(struct Qdisc *sch, unsigned long cl,
 621                           struct sk_buff *skb, struct tcmsg *tcm)
 622 {
 623         tcm->tcm_handle |= TC_H_MIN(cl);
 624         return 0;
 625 }
 626
 627 static int fq_codel_dump_class_stats(struct Qdisc *sch, unsigned long cl,
 628                                      struct gnet_dump *d)
 629 {
 630         struct fq_codel_sched_data *q = qdisc_priv(sch);
 631         u32 idx = cl - 1;
 632         struct gnet_stats_queue qs = { 0 };
 633         struct tc_fq_codel_xstats xstats;
 634
 635         if (idx < q->flows_cnt) {
 636                 const struct fq_codel_flow *flow = &q->flows[idx];
 637                 const struct sk_buff *skb;
 638
 639                 memset(&xstats, 0, sizeof(xstats));
 640                 xstats.type = TCA_FQ_CODEL_XSTATS_CLASS;
 641                 xstats.class_stats.deficit = flow->deficit;
 642                 xstats.class_stats.ldelay =
 643                         codel_time_to_us(flow->cvars.ldelay);
 644                 xstats.class_stats.count = flow->cvars.count;
 645                 xstats.class_stats.lastcount = flow->cvars.lastcount;
 646                 xstats.class_stats.dropping = flow->cvars.dropping;
 647                 if (flow->cvars.dropping) {
 648                         codel_tdiff_t delta = flow->cvars.drop_next -
 649                                               codel_get_time();
 650
 651                         xstats.class_stats.drop_next = (delta >= 0) ?
 652                                 codel_time_to_us(delta) :
 653                                 -codel_time_to_us(-delta);
 654                 }
 655                 if (flow->head) {
 656                         sch_tree_lock(sch);
 657                         skb = flow->head;
 658                         while (skb) {
 659                                 qs.qlen++;
 660                                 skb = skb->next;
 661                         }
 662                         sch_tree_unlock(sch);
 663                 }
 664                 qs.backlog = q->backlogs[idx];
 665                 qs.drops = flow->dropped;
 666         }
 667         if (gnet_stats_copy_queue(d, NULL, &qs, qs.qlen) < 0)
 668                 return -1;
 669         if (idx < q->flows_cnt)
 670                 return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
 671         return 0;
 672 }
 673
 674 static void fq_codel_walk(struct Qdisc *sch, struct qdisc_walker *arg)
 675 {
 676         struct fq_codel_sched_data *q = qdisc_priv(sch);
 677         unsigned int i;
 678
 679         if (arg->stop)
 680                 return;
 681
 682         for (i = 0; i < q->flows_cnt; i++) {
 683                 if (list_empty(&q->flows[i].flowchain) ||
 684                     arg->count < arg->skip) {
 685                         arg->count++;
 686                         continue;
 687                 }
 688                 if (arg->fn(sch, i + 1, arg) < 0) {
 689                         arg->stop = 1;
 690                         break;
 691                 }
 692                 arg->count++;
 693         }
 694 }
 695
 696 static const struct Qdisc_class_ops fq_codel_class_ops = {
 697         .leaf           =       fq_codel_leaf,
 698         .get            =       fq_codel_get,
 699         .put            =       fq_codel_put,
 700         .tcf_chain      =       fq_codel_find_tcf,
 701         .bind_tcf       =       fq_codel_bind,
 702         .unbind_tcf     =       fq_codel_put,
 703         .dump           =       fq_codel_dump_class,
 704         .dump_stats     =       fq_codel_dump_class_stats,
 705         .walk           =       fq_codel_walk,
 706 };
 707
 708 static struct Qdisc_ops fq_codel_qdisc_ops __read_mostly = {
 709         .cl_ops         =       &fq_codel_class_ops,
 710         .id             =       "fq_codel",
 711         .priv_size      =       sizeof(struct fq_codel_sched_data),
 712         .enqueue        =       fq_codel_enqueue,
 713         .dequeue        =       fq_codel_dequeue,
 714         .peek           =       qdisc_peek_dequeued,
 715         .init           =       fq_codel_init,
 716         .reset          =       fq_codel_reset,
 717         .destroy        =       fq_codel_destroy,
 718         .change         =       fq_codel_change,
 719         .dump           =       fq_codel_dump,
 720         .dump_stats =   fq_codel_dump_stats,
 721         .owner          =       THIS_MODULE,
 722 };
 723
 724 static int __init fq_codel_module_init(void)
 725 {
 726         return register_qdisc(&fq_codel_qdisc_ops);
 727 }
 728
 729 static void __exit fq_codel_module_exit(void)
 730 {
 731         unregister_qdisc(&fq_codel_qdisc_ops);
 732 }
 733
 734 module_init(fq_codel_module_init)
 735 module_exit(fq_codel_module_exit)
 736 MODULE_AUTHOR("Eric Dumazet");
 737 MODULE_LICENSE("GPL");