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