net/sched/sch_generic.c

   1 /*
   2  * net/sched/sch_generic.c      Generic packet scheduler routines.
   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  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  10  *              Jamal Hadi Salim, <hadi@cyberus.ca> 990601
  11  *              - Ingress support
  12  */
  13
  14 #include <linux/bitops.h>
  15 #include <linux/module.h>
  16 #include <linux/types.h>
  17 #include <linux/kernel.h>
  18 #include <linux/sched.h>
  19 #include <linux/string.h>
  20 #include <linux/errno.h>
  21 #include <linux/netdevice.h>
  22 #include <linux/skbuff.h>
  23 #include <linux/rtnetlink.h>
  24 #include <linux/init.h>
  25 #include <linux/rcupdate.h>
  26 #include <linux/list.h>
  27 #include <linux/slab.h>
  28 #include <linux/if_vlan.h>
  29 #include <net/sch_generic.h>
  30 #include <net/pkt_sched.h>
  31 #include <net/dst.h>
  32
  33 /* Qdisc to use by default */
  34 const struct Qdisc_ops *default_qdisc_ops = &pfifo_fast_ops;
  35 EXPORT_SYMBOL(default_qdisc_ops);
  36
  37 /* Main transmission queue. */
  38
  39 /* Modifications to data participating in scheduling must be protected with
  40  * qdisc_lock(qdisc) spinlock.
  41  *
  42  * The idea is the following:
  43  * - enqueue, dequeue are serialized via qdisc root lock
  44  * - ingress filtering is also serialized via qdisc root lock
  45  * - updates to tree and tree walking are only done under the rtnl mutex.
  46  */
  47
  48 static inline int dev_requeue_skb(struct sk_buff *skb, struct Qdisc *q)
  49 {
  50         q->gso_skb = skb;
  51         q->qstats.requeues++;
  52         qdisc_qstats_backlog_inc(q, skb);
  53         q->q.qlen++;    /* it's still part of the queue */
  54         __netif_schedule(q);
  55
  56         return 0;
  57 }
  58
  59 static void try_bulk_dequeue_skb(struct Qdisc *q,
  60                                  struct sk_buff *skb,
  61                                  const struct netdev_queue *txq,
  62                                  int *packets)
  63 {
  64         int bytelimit = qdisc_avail_bulklimit(txq) - skb->len;
  65
  66         while (bytelimit > 0) {
  67                 struct sk_buff *nskb = q->dequeue(q);
  68
  69                 if (!nskb)
  70                         break;
  71
  72                 bytelimit -= nskb->len; /* covers GSO len */
  73                 skb->next = nskb;
  74                 skb = nskb;
  75                 (*packets)++; /* GSO counts as one pkt */
  76         }
  77         skb->next = NULL;
  78 }
  79
  80 /* This variant of try_bulk_dequeue_skb() makes sure
  81  * all skbs in the chain are for the same txq
  82  */
  83 static void try_bulk_dequeue_skb_slow(struct Qdisc *q,
  84                                       struct sk_buff *skb,
  85                                       int *packets)
  86 {
  87         int mapping = skb_get_queue_mapping(skb);
  88         struct sk_buff *nskb;
  89         int cnt = 0;
  90
  91         do {
  92                 nskb = q->dequeue(q);
  93                 if (!nskb)
  94                         break;
  95                 if (unlikely(skb_get_queue_mapping(nskb) != mapping)) {
  96                         q->skb_bad_txq = nskb;
  97                         qdisc_qstats_backlog_inc(q, nskb);
  98                         q->q.qlen++;
  99                         break;
 100                 }
 101                 skb->next = nskb;
 102                 skb = nskb;
 103         } while (++cnt < 8);
 104         (*packets) += cnt;
 105         skb->next = NULL;
 106 }
 107
 108 /* Note that dequeue_skb can possibly return a SKB list (via skb->next).
 109  * A requeued skb (via q->gso_skb) can also be a SKB list.
 110  */
 111 static struct sk_buff *dequeue_skb(struct Qdisc *q, bool *validate,
 112                                    int *packets)
 113 {
 114         struct sk_buff *skb = q->gso_skb;
 115         const struct netdev_queue *txq = q->dev_queue;
 116
 117         *packets = 1;
 118         if (unlikely(skb)) {
 119                 /* skb in gso_skb were already validated */
 120                 *validate = false;
 121                 /* check the reason of requeuing without tx lock first */
 122                 txq = skb_get_tx_queue(txq->dev, skb);
 123                 if (!netif_xmit_frozen_or_stopped(txq)) {
 124                         q->gso_skb = NULL;
 125                         qdisc_qstats_backlog_dec(q, skb);
 126                         q->q.qlen--;
 127                 } else
 128                         skb = NULL;
 129                 return skb;
 130         }
 131         *validate = true;
 132         skb = q->skb_bad_txq;
 133         if (unlikely(skb)) {
 134                 /* check the reason of requeuing without tx lock first */
 135                 txq = skb_get_tx_queue(txq->dev, skb);
 136                 if (!netif_xmit_frozen_or_stopped(txq)) {
 137                         q->skb_bad_txq = NULL;
 138                         qdisc_qstats_backlog_dec(q, skb);
 139                         q->q.qlen--;
 140                         goto bulk;
 141                 }
 142                 return NULL;
 143         }
 144         if (!(q->flags & TCQ_F_ONETXQUEUE) ||
 145             !netif_xmit_frozen_or_stopped(txq))
 146                 skb = q->dequeue(q);
 147         if (skb) {
 148 bulk:
 149                 if (qdisc_may_bulk(q))
 150                         try_bulk_dequeue_skb(q, skb, txq, packets);
 151                 else
 152                         try_bulk_dequeue_skb_slow(q, skb, packets);
 153         }
 154         return skb;
 155 }
 156
 157 /*
 158  * Transmit possibly several skbs, and handle the return status as
 159  * required. Owning running seqcount bit guarantees that
 160  * only one CPU can execute this function.
 161  *
 162  * Returns to the caller:
 163  *                              0  - queue is empty or throttled.
 164  *                              >0 - queue is not empty.
 165  */
 166 int sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
 167                     struct net_device *dev, struct netdev_queue *txq,
 168                     spinlock_t *root_lock, bool validate)
 169 {
 170         int ret = NETDEV_TX_BUSY;
 171
 172         /* And release qdisc */
 173         spin_unlock(root_lock);
 174
 175         /* Note that we validate skb (GSO, checksum, ...) outside of locks */
 176         if (validate)
 177                 skb = validate_xmit_skb_list(skb, dev);
 178
 179         if (likely(skb)) {
 180                 HARD_TX_LOCK(dev, txq, smp_processor_id());
 181                 if (!netif_xmit_frozen_or_stopped(txq))
 182                         skb = dev_hard_start_xmit(skb, dev, txq, &ret);
 183
 184                 HARD_TX_UNLOCK(dev, txq);
 185         } else {
 186                 spin_lock(root_lock);
 187                 return qdisc_qlen(q);
 188         }
 189         spin_lock(root_lock);
 190
 191         if (dev_xmit_complete(ret)) {
 192                 /* Driver sent out skb successfully or skb was consumed */
 193                 ret = qdisc_qlen(q);
 194         } else {
 195                 /* Driver returned NETDEV_TX_BUSY - requeue skb */
 196                 if (unlikely(ret != NETDEV_TX_BUSY))
 197                         net_warn_ratelimited("BUG %s code %d qlen %d\n",
 198                                              dev->name, ret, q->q.qlen);
 199
 200                 ret = dev_requeue_skb(skb, q);
 201         }
 202
 203         if (ret && netif_xmit_frozen_or_stopped(txq))
 204                 ret = 0;
 205
 206         return ret;
 207 }
 208
 209 /*
 210  * NOTE: Called under qdisc_lock(q) with locally disabled BH.
 211  *
 212  * running seqcount guarantees only one CPU can process
 213  * this qdisc at a time. qdisc_lock(q) serializes queue accesses for
 214  * this queue.
 215  *
 216  *  netif_tx_lock serializes accesses to device driver.
 217  *
 218  *  qdisc_lock(q) and netif_tx_lock are mutually exclusive,
 219  *  if one is grabbed, another must be free.
 220  *
 221  * Note, that this procedure can be called by a watchdog timer
 222  *
 223  * Returns to the caller:
 224  *                              0  - queue is empty or throttled.
 225  *                              >0 - queue is not empty.
 226  *
 227  */
 228 static inline int qdisc_restart(struct Qdisc *q, int *packets)
 229 {
 230         struct netdev_queue *txq;
 231         struct net_device *dev;
 232         spinlock_t *root_lock;
 233         struct sk_buff *skb;
 234         bool validate;
 235
 236         /* Dequeue packet */
 237         skb = dequeue_skb(q, &validate, packets);
 238         if (unlikely(!skb))
 239                 return 0;
 240
 241         root_lock = qdisc_lock(q);
 242         dev = qdisc_dev(q);
 243         txq = skb_get_tx_queue(dev, skb);
 244
 245         return sch_direct_xmit(skb, q, dev, txq, root_lock, validate);
 246 }
 247
 248 void __qdisc_run(struct Qdisc *q)
 249 {
 250         int quota = weight_p;
 251         int packets;
 252
 253         while (qdisc_restart(q, &packets)) {
 254                 /*
 255                  * Ordered by possible occurrence: Postpone processing if
 256                  * 1. we've exceeded packet quota
 257                  * 2. another process needs the CPU;
 258                  */
 259                 quota -= packets;
 260                 if (quota <= 0 || need_resched()) {
 261                         __netif_schedule(q);
 262                         break;
 263                 }
 264         }
 265
 266         qdisc_run_end(q);
 267 }
 268
 269 unsigned long dev_trans_start(struct net_device *dev)
 270 {
 271         unsigned long val, res;
 272         unsigned int i;
 273
 274         if (is_vlan_dev(dev))
 275                 dev = vlan_dev_real_dev(dev);
 276         res = netdev_get_tx_queue(dev, 0)->trans_start;
 277         for (i = 1; i < dev->num_tx_queues; i++) {
 278                 val = netdev_get_tx_queue(dev, i)->trans_start;
 279                 if (val && time_after(val, res))
 280                         res = val;
 281         }
 282
 283         return res;
 284 }
 285 EXPORT_SYMBOL(dev_trans_start);
 286
 287 static void dev_watchdog(unsigned long arg)
 288 {
 289         struct net_device *dev = (struct net_device *)arg;
 290
 291         netif_tx_lock(dev);
 292         if (!qdisc_tx_is_noop(dev)) {
 293                 if (netif_device_present(dev) &&
 294                     netif_running(dev) &&
 295                     netif_carrier_ok(dev)) {
 296                         int some_queue_timedout = 0;
 297                         unsigned int i;
 298                         unsigned long trans_start;
 299
 300                         for (i = 0; i < dev->num_tx_queues; i++) {
 301                                 struct netdev_queue *txq;
 302
 303                                 txq = netdev_get_tx_queue(dev, i);
 304                                 trans_start = txq->trans_start;
 305                                 if (netif_xmit_stopped(txq) &&
 306                                     time_after(jiffies, (trans_start +
 307                                                          dev->watchdog_timeo))) {
 308                                         some_queue_timedout = 1;
 309                                         txq->trans_timeout++;
 310                                         break;
 311                                 }
 312                         }
 313
 314                         if (some_queue_timedout) {
 315                                 WARN_ONCE(1, KERN_INFO "NETDEV WATCHDOG: %s (%s): transmit queue %u timed out\n",
 316                                        dev->name, netdev_drivername(dev), i);
 317                                 dev->netdev_ops->ndo_tx_timeout(dev);
 318                         }
 319                         if (!mod_timer(&dev->watchdog_timer,
 320                                        round_jiffies(jiffies +
 321                                                      dev->watchdog_timeo)))
 322                                 dev_hold(dev);
 323                 }
 324         }
 325         netif_tx_unlock(dev);
 326
 327         dev_put(dev);
 328 }
 329
 330 void __netdev_watchdog_up(struct net_device *dev)
 331 {
 332         if (dev->netdev_ops->ndo_tx_timeout) {
 333                 if (dev->watchdog_timeo <= 0)
 334                         dev->watchdog_timeo = 5*HZ;
 335                 if (!mod_timer(&dev->watchdog_timer,
 336                                round_jiffies(jiffies + dev->watchdog_timeo)))
 337                         dev_hold(dev);
 338         }
 339 }
 340
 341 static void dev_watchdog_up(struct net_device *dev)
 342 {
 343         __netdev_watchdog_up(dev);
 344 }
 345
 346 static void dev_watchdog_down(struct net_device *dev)
 347 {
 348         netif_tx_lock_bh(dev);
 349         if (del_timer(&dev->watchdog_timer))
 350                 dev_put(dev);
 351         netif_tx_unlock_bh(dev);
 352 }
 353
 354 /**
 355  *      netif_carrier_on - set carrier
 356  *      @dev: network device
 357  *
 358  * Device has detected that carrier.
 359  */
 360 void netif_carrier_on(struct net_device *dev)
 361 {
 362         if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
 363                 if (dev->reg_state == NETREG_UNINITIALIZED)
 364                         return;
 365                 atomic_inc(&dev->carrier_changes);
 366                 linkwatch_fire_event(dev);
 367                 if (netif_running(dev))
 368                         __netdev_watchdog_up(dev);
 369         }
 370 }
 371 EXPORT_SYMBOL(netif_carrier_on);
 372
 373 /**
 374  *      netif_carrier_off - clear carrier
 375  *      @dev: network device
 376  *
 377  * Device has detected loss of carrier.
 378  */
 379 void netif_carrier_off(struct net_device *dev)
 380 {
 381         if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
 382                 if (dev->reg_state == NETREG_UNINITIALIZED)
 383                         return;
 384                 atomic_inc(&dev->carrier_changes);
 385                 linkwatch_fire_event(dev);
 386         }
 387 }
 388 EXPORT_SYMBOL(netif_carrier_off);
 389
 390 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
 391    under all circumstances. It is difficult to invent anything faster or
 392    cheaper.
 393  */
 394
 395 static int noop_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
 396                         struct sk_buff **to_free)
 397 {
 398         __qdisc_drop(skb, to_free);
 399         return NET_XMIT_CN;
 400 }
 401
 402 static struct sk_buff *noop_dequeue(struct Qdisc *qdisc)
 403 {
 404         return NULL;
 405 }
 406
 407 struct Qdisc_ops noop_qdisc_ops __read_mostly = {
 408         .id             =       "noop",
 409         .priv_size      =       0,
 410         .enqueue        =       noop_enqueue,
 411         .dequeue        =       noop_dequeue,
 412         .peek           =       noop_dequeue,
 413         .owner          =       THIS_MODULE,
 414 };
 415
 416 static struct netdev_queue noop_netdev_queue = {
 417         .qdisc          =       &noop_qdisc,
 418         .qdisc_sleeping =       &noop_qdisc,
 419 };
 420
 421 struct Qdisc noop_qdisc = {
 422         .enqueue        =       noop_enqueue,
 423         .dequeue        =       noop_dequeue,
 424         .flags          =       TCQ_F_BUILTIN,
 425         .ops            =       &noop_qdisc_ops,
 426         .q.lock         =       __SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
 427         .dev_queue      =       &noop_netdev_queue,
 428         .running        =       SEQCNT_ZERO(noop_qdisc.running),
 429         .busylock       =       __SPIN_LOCK_UNLOCKED(noop_qdisc.busylock),
 430 };
 431 EXPORT_SYMBOL(noop_qdisc);
 432
 433 static int noqueue_init(struct Qdisc *qdisc, struct nlattr *opt)
 434 {
 435         /* register_qdisc() assigns a default of noop_enqueue if unset,
 436          * but __dev_queue_xmit() treats noqueue only as such
 437          * if this is NULL - so clear it here. */
 438         qdisc->enqueue = NULL;
 439         return 0;
 440 }
 441
 442 struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
 443         .id             =       "noqueue",
 444         .priv_size      =       0,
 445         .init           =       noqueue_init,
 446         .enqueue        =       noop_enqueue,
 447         .dequeue        =       noop_dequeue,
 448         .peek           =       noop_dequeue,
 449         .owner          =       THIS_MODULE,
 450 };
 451
 452 static const u8 prio2band[TC_PRIO_MAX + 1] = {
 453         1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1
 454 };
 455
 456 /* 3-band FIFO queue: old style, but should be a bit faster than
 457    generic prio+fifo combination.
 458  */
 459
 460 #define PFIFO_FAST_BANDS 3
 461
 462 /*
 463  * Private data for a pfifo_fast scheduler containing:
 464  *      - queues for the three band
 465  *      - bitmap indicating which of the bands contain skbs
 466  */
 467 struct pfifo_fast_priv {
 468         u32 bitmap;
 469         struct qdisc_skb_head q[PFIFO_FAST_BANDS];
 470 };
 471
 472 /*
 473  * Convert a bitmap to the first band number where an skb is queued, where:
 474  *      bitmap=0 means there are no skbs on any band.
 475  *      bitmap=1 means there is an skb on band 0.
 476  *      bitmap=7 means there are skbs on all 3 bands, etc.
 477  */
 478 static const int bitmap2band[] = {-1, 0, 1, 0, 2, 0, 1, 0};
 479
 480 static inline struct qdisc_skb_head *band2list(struct pfifo_fast_priv *priv,
 481                                              int band)
 482 {
 483         return priv->q + band;
 484 }
 485
 486 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
 487                               struct sk_buff **to_free)
 488 {
 489         if (qdisc->q.qlen < qdisc_dev(qdisc)->tx_queue_len) {
 490                 int band = prio2band[skb->priority & TC_PRIO_MAX];
 491                 struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 492                 struct qdisc_skb_head *list = band2list(priv, band);
 493
 494                 priv->bitmap |= (1 << band);
 495                 qdisc->q.qlen++;
 496                 return __qdisc_enqueue_tail(skb, qdisc, list);
 497         }
 498
 499         return qdisc_drop(skb, qdisc, to_free);
 500 }
 501
 502 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc *qdisc)
 503 {
 504         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 505         int band = bitmap2band[priv->bitmap];
 506
 507         if (likely(band >= 0)) {
 508                 struct qdisc_skb_head *qh = band2list(priv, band);
 509                 struct sk_buff *skb = __qdisc_dequeue_head(qh);
 510
 511                 if (likely(skb != NULL)) {
 512                         qdisc_qstats_backlog_dec(qdisc, skb);
 513                         qdisc_bstats_update(qdisc, skb);
 514                 }
 515
 516                 qdisc->q.qlen--;
 517                 if (qh->qlen == 0)
 518                         priv->bitmap &= ~(1 << band);
 519
 520                 return skb;
 521         }
 522
 523         return NULL;
 524 }
 525
 526 static struct sk_buff *pfifo_fast_peek(struct Qdisc *qdisc)
 527 {
 528         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 529         int band = bitmap2band[priv->bitmap];
 530
 531         if (band >= 0) {
 532                 struct qdisc_skb_head *qh = band2list(priv, band);
 533
 534                 return qh->head;
 535         }
 536
 537         return NULL;
 538 }
 539
 540 static void pfifo_fast_reset(struct Qdisc *qdisc)
 541 {
 542         int prio;
 543         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 544
 545         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
 546                 __qdisc_reset_queue(band2list(priv, prio));
 547
 548         priv->bitmap = 0;
 549         qdisc->qstats.backlog = 0;
 550         qdisc->q.qlen = 0;
 551 }
 552
 553 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
 554 {
 555         struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
 556
 557         memcpy(&opt.priomap, prio2band, TC_PRIO_MAX + 1);
 558         if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
 559                 goto nla_put_failure;
 560         return skb->len;
 561
 562 nla_put_failure:
 563         return -1;
 564 }
 565
 566 static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt)
 567 {
 568         int prio;
 569         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 570
 571         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
 572                 qdisc_skb_head_init(band2list(priv, prio));
 573
 574         /* Can by-pass the queue discipline */
 575         qdisc->flags |= TCQ_F_CAN_BYPASS;
 576         return 0;
 577 }
 578
 579 struct Qdisc_ops pfifo_fast_ops __read_mostly = {
 580         .id             =       "pfifo_fast",
 581         .priv_size      =       sizeof(struct pfifo_fast_priv),
 582         .enqueue        =       pfifo_fast_enqueue,
 583         .dequeue        =       pfifo_fast_dequeue,
 584         .peek           =       pfifo_fast_peek,
 585         .init           =       pfifo_fast_init,
 586         .reset          =       pfifo_fast_reset,
 587         .dump           =       pfifo_fast_dump,
 588         .owner          =       THIS_MODULE,
 589 };
 590 EXPORT_SYMBOL(pfifo_fast_ops);
 591
 592 static struct lock_class_key qdisc_tx_busylock;
 593 static struct lock_class_key qdisc_running_key;
 594
 595 struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
 596                           const struct Qdisc_ops *ops)
 597 {
 598         void *p;
 599         struct Qdisc *sch;
 600         unsigned int size = QDISC_ALIGN(sizeof(*sch)) + ops->priv_size;
 601         int err = -ENOBUFS;
 602         struct net_device *dev = dev_queue->dev;
 603
 604         p = kzalloc_node(size, GFP_KERNEL,
 605                          netdev_queue_numa_node_read(dev_queue));
 606
 607         if (!p)
 608                 goto errout;
 609         sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
 610         /* if we got non aligned memory, ask more and do alignment ourself */
 611         if (sch != p) {
 612                 kfree(p);
 613                 p = kzalloc_node(size + QDISC_ALIGNTO - 1, GFP_KERNEL,
 614                                  netdev_queue_numa_node_read(dev_queue));
 615                 if (!p)
 616                         goto errout;
 617                 sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
 618                 sch->padded = (char *) sch - (char *) p;
 619         }
 620         qdisc_skb_head_init(&sch->q);
 621         spin_lock_init(&sch->q.lock);
 622
 623         spin_lock_init(&sch->busylock);
 624         lockdep_set_class(&sch->busylock,
 625                           dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
 626
 627         seqcount_init(&sch->running);
 628         lockdep_set_class(&sch->running,
 629                           dev->qdisc_running_key ?: &qdisc_running_key);
 630
 631         sch->ops = ops;
 632         sch->enqueue = ops->enqueue;
 633         sch->dequeue = ops->dequeue;
 634         sch->dev_queue = dev_queue;
 635         dev_hold(dev);
 636         atomic_set(&sch->refcnt, 1);
 637
 638         return sch;
 639 errout:
 640         return ERR_PTR(err);
 641 }
 642
 643 struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
 644                                 const struct Qdisc_ops *ops,
 645                                 unsigned int parentid)
 646 {
 647         struct Qdisc *sch;
 648
 649         if (!try_module_get(ops->owner))
 650                 return NULL;
 651
 652         sch = qdisc_alloc(dev_queue, ops);
 653         if (IS_ERR(sch)) {
 654                 module_put(ops->owner);
 655                 return NULL;
 656         }
 657         sch->parent = parentid;
 658
 659         if (!ops->init || ops->init(sch, NULL) == 0)
 660                 return sch;
 661
 662         qdisc_destroy(sch);
 663         return NULL;
 664 }
 665 EXPORT_SYMBOL(qdisc_create_dflt);
 666
 667 /* Under qdisc_lock(qdisc) and BH! */
 668
 669 void qdisc_reset(struct Qdisc *qdisc)
 670 {
 671         const struct Qdisc_ops *ops = qdisc->ops;
 672
 673         if (ops->reset)
 674                 ops->reset(qdisc);
 675
 676         kfree_skb(qdisc->skb_bad_txq);
 677         qdisc->skb_bad_txq = NULL;
 678
 679         if (qdisc->gso_skb) {
 680                 kfree_skb_list(qdisc->gso_skb);
 681                 qdisc->gso_skb = NULL;
 682         }
 683         qdisc->q.qlen = 0;
 684 }
 685 EXPORT_SYMBOL(qdisc_reset);
 686
 687 static void qdisc_rcu_free(struct rcu_head *head)
 688 {
 689         struct Qdisc *qdisc = container_of(head, struct Qdisc, rcu_head);
 690
 691         if (qdisc_is_percpu_stats(qdisc)) {
 692                 free_percpu(qdisc->cpu_bstats);
 693                 free_percpu(qdisc->cpu_qstats);
 694         }
 695
 696         kfree((char *) qdisc - qdisc->padded);
 697 }
 698
 699 void qdisc_destroy(struct Qdisc *qdisc)
 700 {
 701         const struct Qdisc_ops  *ops = qdisc->ops;
 702
 703         if (qdisc->flags & TCQ_F_BUILTIN ||
 704             !atomic_dec_and_test(&qdisc->refcnt))
 705                 return;
 706
 707 #ifdef CONFIG_NET_SCHED
 708         qdisc_hash_del(qdisc);
 709
 710         qdisc_put_stab(rtnl_dereference(qdisc->stab));
 711 #endif
 712         gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est);
 713         if (ops->reset)
 714                 ops->reset(qdisc);
 715         if (ops->destroy)
 716                 ops->destroy(qdisc);
 717
 718         module_put(ops->owner);
 719         dev_put(qdisc_dev(qdisc));
 720
 721         kfree_skb_list(qdisc->gso_skb);
 722         kfree_skb(qdisc->skb_bad_txq);
 723         /*
 724          * gen_estimator est_timer() might access qdisc->q.lock,
 725          * wait a RCU grace period before freeing qdisc.
 726          */
 727         call_rcu(&qdisc->rcu_head, qdisc_rcu_free);
 728 }
 729 EXPORT_SYMBOL(qdisc_destroy);
 730
 731 /* Attach toplevel qdisc to device queue. */
 732 struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
 733                               struct Qdisc *qdisc)
 734 {
 735         struct Qdisc *oqdisc = dev_queue->qdisc_sleeping;
 736         spinlock_t *root_lock;
 737
 738         root_lock = qdisc_lock(oqdisc);
 739         spin_lock_bh(root_lock);
 740
 741         /* Prune old scheduler */
 742         if (oqdisc && atomic_read(&oqdisc->refcnt) <= 1)
 743                 qdisc_reset(oqdisc);
 744
 745         /* ... and graft new one */
 746         if (qdisc == NULL)
 747                 qdisc = &noop_qdisc;
 748         dev_queue->qdisc_sleeping = qdisc;
 749         rcu_assign_pointer(dev_queue->qdisc, &noop_qdisc);
 750
 751         spin_unlock_bh(root_lock);
 752
 753         return oqdisc;
 754 }
 755 EXPORT_SYMBOL(dev_graft_qdisc);
 756
 757 static void attach_one_default_qdisc(struct net_device *dev,
 758                                      struct netdev_queue *dev_queue,
 759                                      void *_unused)
 760 {
 761         struct Qdisc *qdisc;
 762         const struct Qdisc_ops *ops = default_qdisc_ops;
 763
 764         if (dev->priv_flags & IFF_NO_QUEUE)
 765                 ops = &noqueue_qdisc_ops;
 766
 767         qdisc = qdisc_create_dflt(dev_queue, ops, TC_H_ROOT);
 768         if (!qdisc) {
 769                 netdev_info(dev, "activation failed\n");
 770                 return;
 771         }
 772         if (!netif_is_multiqueue(dev))
 773                 qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
 774         dev_queue->qdisc_sleeping = qdisc;
 775 }
 776
 777 static void attach_default_qdiscs(struct net_device *dev)
 778 {
 779         struct netdev_queue *txq;
 780         struct Qdisc *qdisc;
 781
 782         txq = netdev_get_tx_queue(dev, 0);
 783
 784         if (!netif_is_multiqueue(dev) ||
 785             dev->priv_flags & IFF_NO_QUEUE) {
 786                 netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
 787                 dev->qdisc = txq->qdisc_sleeping;
 788                 atomic_inc(&dev->qdisc->refcnt);
 789         } else {
 790                 qdisc = qdisc_create_dflt(txq, &mq_qdisc_ops, TC_H_ROOT);
 791                 if (qdisc) {
 792                         dev->qdisc = qdisc;
 793                         qdisc->ops->attach(qdisc);
 794                 }
 795         }
 796 #ifdef CONFIG_NET_SCHED
 797         if (dev->qdisc)
 798                 qdisc_hash_add(dev->qdisc);
 799 #endif
 800 }
 801
 802 static void transition_one_qdisc(struct net_device *dev,
 803                                  struct netdev_queue *dev_queue,
 804                                  void *_need_watchdog)
 805 {
 806         struct Qdisc *new_qdisc = dev_queue->qdisc_sleeping;
 807         int *need_watchdog_p = _need_watchdog;
 808
 809         if (!(new_qdisc->flags & TCQ_F_BUILTIN))
 810                 clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state);
 811
 812         rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
 813         if (need_watchdog_p) {
 814                 dev_queue->trans_start = 0;
 815                 *need_watchdog_p = 1;
 816         }
 817 }
 818
 819 void dev_activate(struct net_device *dev)
 820 {
 821         int need_watchdog;
 822
 823         /* No queueing discipline is attached to device;
 824          * create default one for devices, which need queueing
 825          * and noqueue_qdisc for virtual interfaces
 826          */
 827
 828         if (dev->qdisc == &noop_qdisc)
 829                 attach_default_qdiscs(dev);
 830
 831         if (!netif_carrier_ok(dev))
 832                 /* Delay activation until next carrier-on event */
 833                 return;
 834
 835         need_watchdog = 0;
 836         netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
 837         if (dev_ingress_queue(dev))
 838                 transition_one_qdisc(dev, dev_ingress_queue(dev), NULL);
 839
 840         if (need_watchdog) {
 841                 netif_trans_update(dev);
 842                 dev_watchdog_up(dev);
 843         }
 844 }
 845 EXPORT_SYMBOL(dev_activate);
 846
 847 static void dev_deactivate_queue(struct net_device *dev,
 848                                  struct netdev_queue *dev_queue,
 849                                  void *_qdisc_default)
 850 {
 851         struct Qdisc *qdisc_default = _qdisc_default;
 852         struct Qdisc *qdisc;
 853
 854         qdisc = rtnl_dereference(dev_queue->qdisc);
 855         if (qdisc) {
 856                 spin_lock_bh(qdisc_lock(qdisc));
 857
 858                 if (!(qdisc->flags & TCQ_F_BUILTIN))
 859                         set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
 860
 861                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
 862                 qdisc_reset(qdisc);
 863
 864                 spin_unlock_bh(qdisc_lock(qdisc));
 865         }
 866 }
 867
 868 static bool some_qdisc_is_busy(struct net_device *dev)
 869 {
 870         unsigned int i;
 871
 872         for (i = 0; i < dev->num_tx_queues; i++) {
 873                 struct netdev_queue *dev_queue;
 874                 spinlock_t *root_lock;
 875                 struct Qdisc *q;
 876                 int val;
 877
 878                 dev_queue = netdev_get_tx_queue(dev, i);
 879                 q = dev_queue->qdisc_sleeping;
 880                 root_lock = qdisc_lock(q);
 881
 882                 spin_lock_bh(root_lock);
 883
 884                 val = (qdisc_is_running(q) ||
 885                        test_bit(__QDISC_STATE_SCHED, &q->state));
 886
 887                 spin_unlock_bh(root_lock);
 888
 889                 if (val)
 890                         return true;
 891         }
 892         return false;
 893 }
 894
 895 /**
 896  *      dev_deactivate_many - deactivate transmissions on several devices
 897  *      @head: list of devices to deactivate
 898  *
 899  *      This function returns only when all outstanding transmissions
 900  *      have completed, unless all devices are in dismantle phase.
 901  */
 902 void dev_deactivate_many(struct list_head *head)
 903 {
 904         struct net_device *dev;
 905         bool sync_needed = false;
 906
 907         list_for_each_entry(dev, head, close_list) {
 908                 netdev_for_each_tx_queue(dev, dev_deactivate_queue,
 909                                          &noop_qdisc);
 910                 if (dev_ingress_queue(dev))
 911                         dev_deactivate_queue(dev, dev_ingress_queue(dev),
 912                                              &noop_qdisc);
 913
 914                 dev_watchdog_down(dev);
 915                 sync_needed |= !dev->dismantle;
 916         }
 917
 918         /* Wait for outstanding qdisc-less dev_queue_xmit calls.
 919          * This is avoided if all devices are in dismantle phase :
 920          * Caller will call synchronize_net() for us
 921          */
 922         if (sync_needed)
 923                 synchronize_net();
 924
 925         /* Wait for outstanding qdisc_run calls. */
 926         list_for_each_entry(dev, head, close_list)
 927                 while (some_qdisc_is_busy(dev))
 928                         yield();
 929 }
 930
 931 void dev_deactivate(struct net_device *dev)
 932 {
 933         LIST_HEAD(single);
 934
 935         list_add(&dev->close_list, &single);
 936         dev_deactivate_many(&single);
 937         list_del(&single);
 938 }
 939 EXPORT_SYMBOL(dev_deactivate);
 940
 941 static void dev_init_scheduler_queue(struct net_device *dev,
 942                                      struct netdev_queue *dev_queue,
 943                                      void *_qdisc)
 944 {
 945         struct Qdisc *qdisc = _qdisc;
 946
 947         rcu_assign_pointer(dev_queue->qdisc, qdisc);
 948         dev_queue->qdisc_sleeping = qdisc;
 949 }
 950
 951 void dev_init_scheduler(struct net_device *dev)
 952 {
 953         dev->qdisc = &noop_qdisc;
 954         netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
 955         if (dev_ingress_queue(dev))
 956                 dev_init_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
 957
 958         setup_timer(&dev->watchdog_timer, dev_watchdog, (unsigned long)dev);
 959 }
 960
 961 static void shutdown_scheduler_queue(struct net_device *dev,
 962                                      struct netdev_queue *dev_queue,
 963                                      void *_qdisc_default)
 964 {
 965         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
 966         struct Qdisc *qdisc_default = _qdisc_default;
 967
 968         if (qdisc) {
 969                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
 970                 dev_queue->qdisc_sleeping = qdisc_default;
 971
 972                 qdisc_destroy(qdisc);
 973         }
 974 }
 975
 976 void dev_shutdown(struct net_device *dev)
 977 {
 978         netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
 979         if (dev_ingress_queue(dev))
 980                 shutdown_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
 981         qdisc_destroy(dev->qdisc);
 982         dev->qdisc = &noop_qdisc;
 983
 984         WARN_ON(timer_pending(&dev->watchdog_timer));
 985 }
 986
 987 void psched_ratecfg_precompute(struct psched_ratecfg *r,
 988                                const struct tc_ratespec *conf,
 989                                u64 rate64)
 990 {
 991         memset(r, 0, sizeof(*r));
 992         r->overhead = conf->overhead;
 993         r->rate_bytes_ps = max_t(u64, conf->rate, rate64);
 994         r->linklayer = (conf->linklayer & TC_LINKLAYER_MASK);
 995         r->mult = 1;
 996         /*
 997          * The deal here is to replace a divide by a reciprocal one
 998          * in fast path (a reciprocal divide is a multiply and a shift)
 999          *
1000          * Normal formula would be :
1001          *  time_in_ns = (NSEC_PER_SEC * len) / rate_bps
1002          *
1003          * We compute mult/shift to use instead :
1004          *  time_in_ns = (len * mult) >> shift;
1005          *
1006          * We try to get the highest possible mult value for accuracy,
1007          * but have to make sure no overflows will ever happen.
1008          */
1009         if (r->rate_bytes_ps > 0) {
1010                 u64 factor = NSEC_PER_SEC;
1011
1012                 for (;;) {
1013                         r->mult = div64_u64(factor, r->rate_bytes_ps);
1014                         if (r->mult & (1U << 31) || factor & (1ULL << 63))
1015                                 break;
1016                         factor <<= 1;
1017                         r->shift++;
1018                 }
1019         }
1020 }
1021 EXPORT_SYMBOL(psched_ratecfg_precompute);