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