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 <linux/skb_array.h>
  30 #include <linux/if_macvlan.h>
  31 #include <net/sch_generic.h>
  32 #include <net/pkt_sched.h>
  33 #include <net/dst.h>
  34 #include <trace/events/qdisc.h>
  35 #include <net/xfrm.h>
  36
  37 /* Qdisc to use by default */
  38 const struct Qdisc_ops *default_qdisc_ops = &pfifo_fast_ops;
  39 EXPORT_SYMBOL(default_qdisc_ops);
  40
  41 /* Main transmission queue. */
  42
  43 /* Modifications to data participating in scheduling must be protected with
  44  * qdisc_lock(qdisc) spinlock.
  45  *
  46  * The idea is the following:
  47  * - enqueue, dequeue are serialized via qdisc root lock
  48  * - ingress filtering is also serialized via qdisc root lock
  49  * - updates to tree and tree walking are only done under the rtnl mutex.
  50  */
  51
  52 static inline struct sk_buff *__skb_dequeue_bad_txq(struct Qdisc *q)
  53 {
  54         const struct netdev_queue *txq = q->dev_queue;
  55         spinlock_t *lock = NULL;
  56         struct sk_buff *skb;
  57
  58         if (q->flags & TCQ_F_NOLOCK) {
  59                 lock = qdisc_lock(q);
  60                 spin_lock(lock);
  61         }
  62
  63         skb = skb_peek(&q->skb_bad_txq);
  64         if (skb) {
  65                 /* check the reason of requeuing without tx lock first */
  66                 txq = skb_get_tx_queue(txq->dev, skb);
  67                 if (!netif_xmit_frozen_or_stopped(txq)) {
  68                         skb = __skb_dequeue(&q->skb_bad_txq);
  69                         if (qdisc_is_percpu_stats(q)) {
  70                                 qdisc_qstats_cpu_backlog_dec(q, skb);
  71                                 qdisc_qstats_cpu_qlen_dec(q);
  72                         } else {
  73                                 qdisc_qstats_backlog_dec(q, skb);
  74                                 q->q.qlen--;
  75                         }
  76                 } else {
  77                         skb = NULL;
  78                 }
  79         }
  80
  81         if (lock)
  82                 spin_unlock(lock);
  83
  84         return skb;
  85 }
  86
  87 static inline struct sk_buff *qdisc_dequeue_skb_bad_txq(struct Qdisc *q)
  88 {
  89         struct sk_buff *skb = skb_peek(&q->skb_bad_txq);
  90
  91         if (unlikely(skb))
  92                 skb = __skb_dequeue_bad_txq(q);
  93
  94         return skb;
  95 }
  96
  97 static inline void qdisc_enqueue_skb_bad_txq(struct Qdisc *q,
  98                                              struct sk_buff *skb)
  99 {
 100         spinlock_t *lock = NULL;
 101
 102         if (q->flags & TCQ_F_NOLOCK) {
 103                 lock = qdisc_lock(q);
 104                 spin_lock(lock);
 105         }
 106
 107         __skb_queue_tail(&q->skb_bad_txq, skb);
 108
 109         if (qdisc_is_percpu_stats(q)) {
 110                 qdisc_qstats_cpu_backlog_inc(q, skb);
 111                 qdisc_qstats_cpu_qlen_inc(q);
 112         } else {
 113                 qdisc_qstats_backlog_inc(q, skb);
 114                 q->q.qlen++;
 115         }
 116
 117         if (lock)
 118                 spin_unlock(lock);
 119 }
 120
 121 static inline int __dev_requeue_skb(struct sk_buff *skb, struct Qdisc *q)
 122 {
 123         while (skb) {
 124                 struct sk_buff *next = skb->next;
 125
 126                 __skb_queue_tail(&q->gso_skb, skb);
 127                 q->qstats.requeues++;
 128                 qdisc_qstats_backlog_inc(q, skb);
 129                 q->q.qlen++;    /* it's still part of the queue */
 130
 131                 skb = next;
 132         }
 133         __netif_schedule(q);
 134
 135         return 0;
 136 }
 137
 138 static inline int dev_requeue_skb_locked(struct sk_buff *skb, struct Qdisc *q)
 139 {
 140         spinlock_t *lock = qdisc_lock(q);
 141
 142         spin_lock(lock);
 143         while (skb) {
 144                 struct sk_buff *next = skb->next;
 145
 146                 __skb_queue_tail(&q->gso_skb, skb);
 147
 148                 qdisc_qstats_cpu_requeues_inc(q);
 149                 qdisc_qstats_cpu_backlog_inc(q, skb);
 150                 qdisc_qstats_cpu_qlen_inc(q);
 151
 152                 skb = next;
 153         }
 154         spin_unlock(lock);
 155
 156         __netif_schedule(q);
 157
 158         return 0;
 159 }
 160
 161 static inline int dev_requeue_skb(struct sk_buff *skb, struct Qdisc *q)
 162 {
 163         if (q->flags & TCQ_F_NOLOCK)
 164                 return dev_requeue_skb_locked(skb, q);
 165         else
 166                 return __dev_requeue_skb(skb, q);
 167 }
 168
 169 static void try_bulk_dequeue_skb(struct Qdisc *q,
 170                                  struct sk_buff *skb,
 171                                  const struct netdev_queue *txq,
 172                                  int *packets)
 173 {
 174         int bytelimit = qdisc_avail_bulklimit(txq) - skb->len;
 175
 176         while (bytelimit > 0) {
 177                 struct sk_buff *nskb = q->dequeue(q);
 178
 179                 if (!nskb)
 180                         break;
 181
 182                 bytelimit -= nskb->len; /* covers GSO len */
 183                 skb->next = nskb;
 184                 skb = nskb;
 185                 (*packets)++; /* GSO counts as one pkt */
 186         }
 187         skb->next = NULL;
 188 }
 189
 190 /* This variant of try_bulk_dequeue_skb() makes sure
 191  * all skbs in the chain are for the same txq
 192  */
 193 static void try_bulk_dequeue_skb_slow(struct Qdisc *q,
 194                                       struct sk_buff *skb,
 195                                       int *packets)
 196 {
 197         int mapping = skb_get_queue_mapping(skb);
 198         struct sk_buff *nskb;
 199         int cnt = 0;
 200
 201         do {
 202                 nskb = q->dequeue(q);
 203                 if (!nskb)
 204                         break;
 205                 if (unlikely(skb_get_queue_mapping(nskb) != mapping)) {
 206                         qdisc_enqueue_skb_bad_txq(q, nskb);
 207                         break;
 208                 }
 209                 skb->next = nskb;
 210                 skb = nskb;
 211         } while (++cnt < 8);
 212         (*packets) += cnt;
 213         skb->next = NULL;
 214 }
 215
 216 /* Note that dequeue_skb can possibly return a SKB list (via skb->next).
 217  * A requeued skb (via q->gso_skb) can also be a SKB list.
 218  */
 219 static struct sk_buff *dequeue_skb(struct Qdisc *q, bool *validate,
 220                                    int *packets)
 221 {
 222         const struct netdev_queue *txq = q->dev_queue;
 223         struct sk_buff *skb = NULL;
 224
 225         *packets = 1;
 226         if (unlikely(!skb_queue_empty(&q->gso_skb))) {
 227                 spinlock_t *lock = NULL;
 228
 229                 if (q->flags & TCQ_F_NOLOCK) {
 230                         lock = qdisc_lock(q);
 231                         spin_lock(lock);
 232                 }
 233
 234                 skb = skb_peek(&q->gso_skb);
 235
 236                 /* skb may be null if another cpu pulls gso_skb off in between
 237                  * empty check and lock.
 238                  */
 239                 if (!skb) {
 240                         if (lock)
 241                                 spin_unlock(lock);
 242                         goto validate;
 243                 }
 244
 245                 /* skb in gso_skb were already validated */
 246                 *validate = false;
 247                 if (xfrm_offload(skb))
 248                         *validate = true;
 249                 /* check the reason of requeuing without tx lock first */
 250                 txq = skb_get_tx_queue(txq->dev, skb);
 251                 if (!netif_xmit_frozen_or_stopped(txq)) {
 252                         skb = __skb_dequeue(&q->gso_skb);
 253                         if (qdisc_is_percpu_stats(q)) {
 254                                 qdisc_qstats_cpu_backlog_dec(q, skb);
 255                                 qdisc_qstats_cpu_qlen_dec(q);
 256                         } else {
 257                                 qdisc_qstats_backlog_dec(q, skb);
 258                                 q->q.qlen--;
 259                         }
 260                 } else {
 261                         skb = NULL;
 262                 }
 263                 if (lock)
 264                         spin_unlock(lock);
 265                 goto trace;
 266         }
 267 validate:
 268         *validate = true;
 269
 270         if ((q->flags & TCQ_F_ONETXQUEUE) &&
 271             netif_xmit_frozen_or_stopped(txq))
 272                 return skb;
 273
 274         skb = qdisc_dequeue_skb_bad_txq(q);
 275         if (unlikely(skb))
 276                 goto bulk;
 277         skb = q->dequeue(q);
 278         if (skb) {
 279 bulk:
 280                 if (qdisc_may_bulk(q))
 281                         try_bulk_dequeue_skb(q, skb, txq, packets);
 282                 else
 283                         try_bulk_dequeue_skb_slow(q, skb, packets);
 284         }
 285 trace:
 286         trace_qdisc_dequeue(q, txq, *packets, skb);
 287         return skb;
 288 }
 289
 290 /*
 291  * Transmit possibly several skbs, and handle the return status as
 292  * required. Owning running seqcount bit guarantees that
 293  * only one CPU can execute this function.
 294  *
 295  * Returns to the caller:
 296  *                              false  - hardware queue frozen backoff
 297  *                              true   - feel free to send more pkts
 298  */
 299 bool sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
 300                      struct net_device *dev, struct netdev_queue *txq,
 301                      spinlock_t *root_lock, bool validate)
 302 {
 303         int ret = NETDEV_TX_BUSY;
 304         bool again = false;
 305
 306         /* And release qdisc */
 307         if (root_lock)
 308                 spin_unlock(root_lock);
 309
 310         /* Note that we validate skb (GSO, checksum, ...) outside of locks */
 311         if (validate)
 312                 skb = validate_xmit_skb_list(skb, dev, &again);
 313
 314 #ifdef CONFIG_XFRM_OFFLOAD
 315         if (unlikely(again)) {
 316                 if (root_lock)
 317                         spin_lock(root_lock);
 318
 319                 dev_requeue_skb(skb, q);
 320                 return false;
 321         }
 322 #endif
 323
 324         if (likely(skb)) {
 325                 HARD_TX_LOCK(dev, txq, smp_processor_id());
 326                 if (!netif_xmit_frozen_or_stopped(txq))
 327                         skb = dev_hard_start_xmit(skb, dev, txq, &ret);
 328
 329                 HARD_TX_UNLOCK(dev, txq);
 330         } else {
 331                 if (root_lock)
 332                         spin_lock(root_lock);
 333                 return true;
 334         }
 335
 336         if (root_lock)
 337                 spin_lock(root_lock);
 338
 339         if (!dev_xmit_complete(ret)) {
 340                 /* Driver returned NETDEV_TX_BUSY - requeue skb */
 341                 if (unlikely(ret != NETDEV_TX_BUSY))
 342                         net_warn_ratelimited("BUG %s code %d qlen %d\n",
 343                                              dev->name, ret, q->q.qlen);
 344
 345                 dev_requeue_skb(skb, q);
 346                 return false;
 347         }
 348
 349         if (ret && netif_xmit_frozen_or_stopped(txq))
 350                 return false;
 351
 352         return true;
 353 }
 354
 355 /*
 356  * NOTE: Called under qdisc_lock(q) with locally disabled BH.
 357  *
 358  * running seqcount guarantees only one CPU can process
 359  * this qdisc at a time. qdisc_lock(q) serializes queue accesses for
 360  * this queue.
 361  *
 362  *  netif_tx_lock serializes accesses to device driver.
 363  *
 364  *  qdisc_lock(q) and netif_tx_lock are mutually exclusive,
 365  *  if one is grabbed, another must be free.
 366  *
 367  * Note, that this procedure can be called by a watchdog timer
 368  *
 369  * Returns to the caller:
 370  *                              0  - queue is empty or throttled.
 371  *                              >0 - queue is not empty.
 372  *
 373  */
 374 static inline bool qdisc_restart(struct Qdisc *q, int *packets)
 375 {
 376         bool more, validate, nolock = q->flags & TCQ_F_NOLOCK;
 377         spinlock_t *root_lock = NULL;
 378         struct netdev_queue *txq;
 379         struct net_device *dev;
 380         struct sk_buff *skb;
 381
 382         /* Dequeue packet */
 383         if (nolock && test_and_set_bit(__QDISC_STATE_RUNNING, &q->state))
 384                 return false;
 385
 386         skb = dequeue_skb(q, &validate, packets);
 387         if (unlikely(!skb)) {
 388                 if (nolock)
 389                         clear_bit(__QDISC_STATE_RUNNING, &q->state);
 390                 return false;
 391         }
 392
 393         if (!nolock)
 394                 root_lock = qdisc_lock(q);
 395
 396         dev = qdisc_dev(q);
 397         txq = skb_get_tx_queue(dev, skb);
 398
 399         more = sch_direct_xmit(skb, q, dev, txq, root_lock, validate);
 400         if (nolock)
 401                 clear_bit(__QDISC_STATE_RUNNING, &q->state);
 402         return more;
 403 }
 404
 405 void __qdisc_run(struct Qdisc *q)
 406 {
 407         int quota = dev_tx_weight;
 408         int packets;
 409
 410         while (qdisc_restart(q, &packets)) {
 411                 /*
 412                  * Ordered by possible occurrence: Postpone processing if
 413                  * 1. we've exceeded packet quota
 414                  * 2. another process needs the CPU;
 415                  */
 416                 quota -= packets;
 417                 if (quota <= 0 || need_resched()) {
 418                         __netif_schedule(q);
 419                         break;
 420                 }
 421         }
 422 }
 423
 424 unsigned long dev_trans_start(struct net_device *dev)
 425 {
 426         unsigned long val, res;
 427         unsigned int i;
 428
 429         if (is_vlan_dev(dev))
 430                 dev = vlan_dev_real_dev(dev);
 431         else if (netif_is_macvlan(dev))
 432                 dev = macvlan_dev_real_dev(dev);
 433         res = netdev_get_tx_queue(dev, 0)->trans_start;
 434         for (i = 1; i < dev->num_tx_queues; i++) {
 435                 val = netdev_get_tx_queue(dev, i)->trans_start;
 436                 if (val && time_after(val, res))
 437                         res = val;
 438         }
 439
 440         return res;
 441 }
 442 EXPORT_SYMBOL(dev_trans_start);
 443
 444 static void dev_watchdog(struct timer_list *t)
 445 {
 446         struct net_device *dev = from_timer(dev, t, watchdog_timer);
 447
 448         netif_tx_lock(dev);
 449         if (!qdisc_tx_is_noop(dev)) {
 450                 if (netif_device_present(dev) &&
 451                     netif_running(dev) &&
 452                     netif_carrier_ok(dev)) {
 453                         int some_queue_timedout = 0;
 454                         unsigned int i;
 455                         unsigned long trans_start;
 456
 457                         for (i = 0; i < dev->num_tx_queues; i++) {
 458                                 struct netdev_queue *txq;
 459
 460                                 txq = netdev_get_tx_queue(dev, i);
 461                                 trans_start = txq->trans_start;
 462                                 if (netif_xmit_stopped(txq) &&
 463                                     time_after(jiffies, (trans_start +
 464                                                          dev->watchdog_timeo))) {
 465                                         some_queue_timedout = 1;
 466                                         txq->trans_timeout++;
 467                                         break;
 468                                 }
 469                         }
 470
 471                         if (some_queue_timedout) {
 472                                 WARN_ONCE(1, KERN_INFO "NETDEV WATCHDOG: %s (%s): transmit queue %u timed out\n",
 473                                        dev->name, netdev_drivername(dev), i);
 474                                 dev->netdev_ops->ndo_tx_timeout(dev);
 475                         }
 476                         if (!mod_timer(&dev->watchdog_timer,
 477                                        round_jiffies(jiffies +
 478                                                      dev->watchdog_timeo)))
 479                                 dev_hold(dev);
 480                 }
 481         }
 482         netif_tx_unlock(dev);
 483
 484         dev_put(dev);
 485 }
 486
 487 void __netdev_watchdog_up(struct net_device *dev)
 488 {
 489         if (dev->netdev_ops->ndo_tx_timeout) {
 490                 if (dev->watchdog_timeo <= 0)
 491                         dev->watchdog_timeo = 5*HZ;
 492                 if (!mod_timer(&dev->watchdog_timer,
 493                                round_jiffies(jiffies + dev->watchdog_timeo)))
 494                         dev_hold(dev);
 495         }
 496 }
 497
 498 static void dev_watchdog_up(struct net_device *dev)
 499 {
 500         __netdev_watchdog_up(dev);
 501 }
 502
 503 static void dev_watchdog_down(struct net_device *dev)
 504 {
 505         netif_tx_lock_bh(dev);
 506         if (del_timer(&dev->watchdog_timer))
 507                 dev_put(dev);
 508         netif_tx_unlock_bh(dev);
 509 }
 510
 511 /**
 512  *      netif_carrier_on - set carrier
 513  *      @dev: network device
 514  *
 515  * Device has detected that carrier.
 516  */
 517 void netif_carrier_on(struct net_device *dev)
 518 {
 519         if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
 520                 if (dev->reg_state == NETREG_UNINITIALIZED)
 521                         return;
 522                 atomic_inc(&dev->carrier_up_count);
 523                 linkwatch_fire_event(dev);
 524                 if (netif_running(dev))
 525                         __netdev_watchdog_up(dev);
 526         }
 527 }
 528 EXPORT_SYMBOL(netif_carrier_on);
 529
 530 /**
 531  *      netif_carrier_off - clear carrier
 532  *      @dev: network device
 533  *
 534  * Device has detected loss of carrier.
 535  */
 536 void netif_carrier_off(struct net_device *dev)
 537 {
 538         if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
 539                 if (dev->reg_state == NETREG_UNINITIALIZED)
 540                         return;
 541                 atomic_inc(&dev->carrier_down_count);
 542                 linkwatch_fire_event(dev);
 543         }
 544 }
 545 EXPORT_SYMBOL(netif_carrier_off);
 546
 547 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
 548    under all circumstances. It is difficult to invent anything faster or
 549    cheaper.
 550  */
 551
 552 static int noop_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
 553                         struct sk_buff **to_free)
 554 {
 555         __qdisc_drop(skb, to_free);
 556         return NET_XMIT_CN;
 557 }
 558
 559 static struct sk_buff *noop_dequeue(struct Qdisc *qdisc)
 560 {
 561         return NULL;
 562 }
 563
 564 struct Qdisc_ops noop_qdisc_ops __read_mostly = {
 565         .id             =       "noop",
 566         .priv_size      =       0,
 567         .enqueue        =       noop_enqueue,
 568         .dequeue        =       noop_dequeue,
 569         .peek           =       noop_dequeue,
 570         .owner          =       THIS_MODULE,
 571 };
 572
 573 static struct netdev_queue noop_netdev_queue = {
 574         .qdisc          =       &noop_qdisc,
 575         .qdisc_sleeping =       &noop_qdisc,
 576 };
 577
 578 struct Qdisc noop_qdisc = {
 579         .enqueue        =       noop_enqueue,
 580         .dequeue        =       noop_dequeue,
 581         .flags          =       TCQ_F_BUILTIN,
 582         .ops            =       &noop_qdisc_ops,
 583         .q.lock         =       __SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
 584         .dev_queue      =       &noop_netdev_queue,
 585         .running        =       SEQCNT_ZERO(noop_qdisc.running),
 586         .busylock       =       __SPIN_LOCK_UNLOCKED(noop_qdisc.busylock),
 587 };
 588 EXPORT_SYMBOL(noop_qdisc);
 589
 590 static int noqueue_init(struct Qdisc *qdisc, struct nlattr *opt,
 591                         struct netlink_ext_ack *extack)
 592 {
 593         /* register_qdisc() assigns a default of noop_enqueue if unset,
 594          * but __dev_queue_xmit() treats noqueue only as such
 595          * if this is NULL - so clear it here. */
 596         qdisc->enqueue = NULL;
 597         return 0;
 598 }
 599
 600 struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
 601         .id             =       "noqueue",
 602         .priv_size      =       0,
 603         .init           =       noqueue_init,
 604         .enqueue        =       noop_enqueue,
 605         .dequeue        =       noop_dequeue,
 606         .peek           =       noop_dequeue,
 607         .owner          =       THIS_MODULE,
 608 };
 609
 610 static const u8 prio2band[TC_PRIO_MAX + 1] = {
 611         1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1
 612 };
 613
 614 /* 3-band FIFO queue: old style, but should be a bit faster than
 615    generic prio+fifo combination.
 616  */
 617
 618 #define PFIFO_FAST_BANDS 3
 619
 620 /*
 621  * Private data for a pfifo_fast scheduler containing:
 622  *      - rings for priority bands
 623  */
 624 struct pfifo_fast_priv {
 625         struct skb_array q[PFIFO_FAST_BANDS];
 626 };
 627
 628 static inline struct skb_array *band2list(struct pfifo_fast_priv *priv,
 629                                           int band)
 630 {
 631         return &priv->q[band];
 632 }
 633
 634 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
 635                               struct sk_buff **to_free)
 636 {
 637         int band = prio2band[skb->priority & TC_PRIO_MAX];
 638         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 639         struct skb_array *q = band2list(priv, band);
 640         unsigned int pkt_len = qdisc_pkt_len(skb);
 641         int err;
 642
 643         err = skb_array_produce(q, skb);
 644
 645         if (unlikely(err))
 646                 return qdisc_drop_cpu(skb, qdisc, to_free);
 647
 648         qdisc_qstats_cpu_qlen_inc(qdisc);
 649         /* Note: skb can not be used after skb_array_produce(),
 650          * so we better not use qdisc_qstats_cpu_backlog_inc()
 651          */
 652         this_cpu_add(qdisc->cpu_qstats->backlog, pkt_len);
 653         return NET_XMIT_SUCCESS;
 654 }
 655
 656 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc *qdisc)
 657 {
 658         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 659         struct sk_buff *skb = NULL;
 660         int band;
 661
 662         for (band = 0; band < PFIFO_FAST_BANDS && !skb; band++) {
 663                 struct skb_array *q = band2list(priv, band);
 664
 665                 if (__skb_array_empty(q))
 666                         continue;
 667
 668                 skb = skb_array_consume_bh(q);
 669         }
 670         if (likely(skb)) {
 671                 qdisc_qstats_cpu_backlog_dec(qdisc, skb);
 672                 qdisc_bstats_cpu_update(qdisc, skb);
 673                 qdisc_qstats_cpu_qlen_dec(qdisc);
 674         }
 675
 676         return skb;
 677 }
 678
 679 static struct sk_buff *pfifo_fast_peek(struct Qdisc *qdisc)
 680 {
 681         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 682         struct sk_buff *skb = NULL;
 683         int band;
 684
 685         for (band = 0; band < PFIFO_FAST_BANDS && !skb; band++) {
 686                 struct skb_array *q = band2list(priv, band);
 687
 688                 skb = __skb_array_peek(q);
 689         }
 690
 691         return skb;
 692 }
 693
 694 static void pfifo_fast_reset(struct Qdisc *qdisc)
 695 {
 696         int i, band;
 697         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 698
 699         for (band = 0; band < PFIFO_FAST_BANDS; band++) {
 700                 struct skb_array *q = band2list(priv, band);
 701                 struct sk_buff *skb;
 702
 703                 /* NULL ring is possible if destroy path is due to a failed
 704                  * skb_array_init() in pfifo_fast_init() case.
 705                  */
 706                 if (!q->ring.queue)
 707                         continue;
 708
 709                 while ((skb = skb_array_consume_bh(q)) != NULL)
 710                         kfree_skb(skb);
 711         }
 712
 713         for_each_possible_cpu(i) {
 714                 struct gnet_stats_queue *q = per_cpu_ptr(qdisc->cpu_qstats, i);
 715
 716                 q->backlog = 0;
 717                 q->qlen = 0;
 718         }
 719 }
 720
 721 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
 722 {
 723         struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
 724
 725         memcpy(&opt.priomap, prio2band, TC_PRIO_MAX + 1);
 726         if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
 727                 goto nla_put_failure;
 728         return skb->len;
 729
 730 nla_put_failure:
 731         return -1;
 732 }
 733
 734 static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt,
 735                            struct netlink_ext_ack *extack)
 736 {
 737         unsigned int qlen = qdisc_dev(qdisc)->tx_queue_len;
 738         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 739         int prio;
 740
 741         /* guard against zero length rings */
 742         if (!qlen)
 743                 return -EINVAL;
 744
 745         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
 746                 struct skb_array *q = band2list(priv, prio);
 747                 int err;
 748
 749                 err = skb_array_init(q, qlen, GFP_KERNEL);
 750                 if (err)
 751                         return -ENOMEM;
 752         }
 753
 754         /* Can by-pass the queue discipline */
 755         qdisc->flags |= TCQ_F_CAN_BYPASS;
 756         return 0;
 757 }
 758
 759 static void pfifo_fast_destroy(struct Qdisc *sch)
 760 {
 761         struct pfifo_fast_priv *priv = qdisc_priv(sch);
 762         int prio;
 763
 764         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
 765                 struct skb_array *q = band2list(priv, prio);
 766
 767                 /* NULL ring is possible if destroy path is due to a failed
 768                  * skb_array_init() in pfifo_fast_init() case.
 769                  */
 770                 if (!q->ring.queue)
 771                         continue;
 772                 /* Destroy ring but no need to kfree_skb because a call to
 773                  * pfifo_fast_reset() has already done that work.
 774                  */
 775                 ptr_ring_cleanup(&q->ring, NULL);
 776         }
 777 }
 778
 779 static int pfifo_fast_change_tx_queue_len(struct Qdisc *sch,
 780                                           unsigned int new_len)
 781 {
 782         struct pfifo_fast_priv *priv = qdisc_priv(sch);
 783         struct skb_array *bands[PFIFO_FAST_BANDS];
 784         int prio;
 785
 786         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
 787                 struct skb_array *q = band2list(priv, prio);
 788
 789                 bands[prio] = q;
 790         }
 791
 792         return skb_array_resize_multiple(bands, PFIFO_FAST_BANDS, new_len,
 793                                          GFP_KERNEL);
 794 }
 795
 796 struct Qdisc_ops pfifo_fast_ops __read_mostly = {
 797         .id             =       "pfifo_fast",
 798         .priv_size      =       sizeof(struct pfifo_fast_priv),
 799         .enqueue        =       pfifo_fast_enqueue,
 800         .dequeue        =       pfifo_fast_dequeue,
 801         .peek           =       pfifo_fast_peek,
 802         .init           =       pfifo_fast_init,
 803         .destroy        =       pfifo_fast_destroy,
 804         .reset          =       pfifo_fast_reset,
 805         .dump           =       pfifo_fast_dump,
 806         .change_tx_queue_len =  pfifo_fast_change_tx_queue_len,
 807         .owner          =       THIS_MODULE,
 808         .static_flags   =       TCQ_F_NOLOCK | TCQ_F_CPUSTATS,
 809 };
 810 EXPORT_SYMBOL(pfifo_fast_ops);
 811
 812 static struct lock_class_key qdisc_tx_busylock;
 813 static struct lock_class_key qdisc_running_key;
 814
 815 struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
 816                           const struct Qdisc_ops *ops,
 817                           struct netlink_ext_ack *extack)
 818 {
 819         void *p;
 820         struct Qdisc *sch;
 821         unsigned int size = QDISC_ALIGN(sizeof(*sch)) + ops->priv_size;
 822         int err = -ENOBUFS;
 823         struct net_device *dev;
 824
 825         if (!dev_queue) {
 826                 NL_SET_ERR_MSG(extack, "No device queue given");
 827                 err = -EINVAL;
 828                 goto errout;
 829         }
 830
 831         dev = dev_queue->dev;
 832         p = kzalloc_node(size, GFP_KERNEL,
 833                          netdev_queue_numa_node_read(dev_queue));
 834
 835         if (!p)
 836                 goto errout;
 837         sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
 838         /* if we got non aligned memory, ask more and do alignment ourself */
 839         if (sch != p) {
 840                 kfree(p);
 841                 p = kzalloc_node(size + QDISC_ALIGNTO - 1, GFP_KERNEL,
 842                                  netdev_queue_numa_node_read(dev_queue));
 843                 if (!p)
 844                         goto errout;
 845                 sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
 846                 sch->padded = (char *) sch - (char *) p;
 847         }
 848         __skb_queue_head_init(&sch->gso_skb);
 849         __skb_queue_head_init(&sch->skb_bad_txq);
 850         qdisc_skb_head_init(&sch->q);
 851         spin_lock_init(&sch->q.lock);
 852
 853         if (ops->static_flags & TCQ_F_CPUSTATS) {
 854                 sch->cpu_bstats =
 855                         netdev_alloc_pcpu_stats(struct gnet_stats_basic_cpu);
 856                 if (!sch->cpu_bstats)
 857                         goto errout1;
 858
 859                 sch->cpu_qstats = alloc_percpu(struct gnet_stats_queue);
 860                 if (!sch->cpu_qstats) {
 861                         free_percpu(sch->cpu_bstats);
 862                         goto errout1;
 863                 }
 864         }
 865
 866         spin_lock_init(&sch->busylock);
 867         lockdep_set_class(&sch->busylock,
 868                           dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
 869
 870         seqcount_init(&sch->running);
 871         lockdep_set_class(&sch->running,
 872                           dev->qdisc_running_key ?: &qdisc_running_key);
 873
 874         sch->ops = ops;
 875         sch->flags = ops->static_flags;
 876         sch->enqueue = ops->enqueue;
 877         sch->dequeue = ops->dequeue;
 878         sch->dev_queue = dev_queue;
 879         dev_hold(dev);
 880         refcount_set(&sch->refcnt, 1);
 881
 882         return sch;
 883 errout1:
 884         kfree(p);
 885 errout:
 886         return ERR_PTR(err);
 887 }
 888
 889 struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
 890                                 const struct Qdisc_ops *ops,
 891                                 unsigned int parentid,
 892                                 struct netlink_ext_ack *extack)
 893 {
 894         struct Qdisc *sch;
 895
 896         if (!try_module_get(ops->owner)) {
 897                 NL_SET_ERR_MSG(extack, "Failed to increase module reference counter");
 898                 return NULL;
 899         }
 900
 901         sch = qdisc_alloc(dev_queue, ops, extack);
 902         if (IS_ERR(sch)) {
 903                 module_put(ops->owner);
 904                 return NULL;
 905         }
 906         sch->parent = parentid;
 907
 908         if (!ops->init || ops->init(sch, NULL, extack) == 0)
 909                 return sch;
 910
 911         qdisc_destroy(sch);
 912         return NULL;
 913 }
 914 EXPORT_SYMBOL(qdisc_create_dflt);
 915
 916 /* Under qdisc_lock(qdisc) and BH! */
 917
 918 void qdisc_reset(struct Qdisc *qdisc)
 919 {
 920         const struct Qdisc_ops *ops = qdisc->ops;
 921         struct sk_buff *skb, *tmp;
 922
 923         if (ops->reset)
 924                 ops->reset(qdisc);
 925
 926         skb_queue_walk_safe(&qdisc->gso_skb, skb, tmp) {
 927                 __skb_unlink(skb, &qdisc->gso_skb);
 928                 kfree_skb_list(skb);
 929         }
 930
 931         skb_queue_walk_safe(&qdisc->skb_bad_txq, skb, tmp) {
 932                 __skb_unlink(skb, &qdisc->skb_bad_txq);
 933                 kfree_skb_list(skb);
 934         }
 935
 936         qdisc->q.qlen = 0;
 937         qdisc->qstats.backlog = 0;
 938 }
 939 EXPORT_SYMBOL(qdisc_reset);
 940
 941 void qdisc_free(struct Qdisc *qdisc)
 942 {
 943         if (qdisc_is_percpu_stats(qdisc)) {
 944                 free_percpu(qdisc->cpu_bstats);
 945                 free_percpu(qdisc->cpu_qstats);
 946         }
 947
 948         kfree((char *) qdisc - qdisc->padded);
 949 }
 950
 951 void qdisc_destroy(struct Qdisc *qdisc)
 952 {
 953         const struct Qdisc_ops  *ops = qdisc->ops;
 954         struct sk_buff *skb, *tmp;
 955
 956         if (qdisc->flags & TCQ_F_BUILTIN ||
 957             !refcount_dec_and_test(&qdisc->refcnt))
 958                 return;
 959
 960 #ifdef CONFIG_NET_SCHED
 961         qdisc_hash_del(qdisc);
 962
 963         qdisc_put_stab(rtnl_dereference(qdisc->stab));
 964 #endif
 965         gen_kill_estimator(&qdisc->rate_est);
 966         if (ops->reset)
 967                 ops->reset(qdisc);
 968         if (ops->destroy)
 969                 ops->destroy(qdisc);
 970
 971         module_put(ops->owner);
 972         dev_put(qdisc_dev(qdisc));
 973
 974         skb_queue_walk_safe(&qdisc->gso_skb, skb, tmp) {
 975                 __skb_unlink(skb, &qdisc->gso_skb);
 976                 kfree_skb_list(skb);
 977         }
 978
 979         skb_queue_walk_safe(&qdisc->skb_bad_txq, skb, tmp) {
 980                 __skb_unlink(skb, &qdisc->skb_bad_txq);
 981                 kfree_skb_list(skb);
 982         }
 983
 984         qdisc_free(qdisc);
 985 }
 986 EXPORT_SYMBOL(qdisc_destroy);
 987
 988 /* Attach toplevel qdisc to device queue. */
 989 struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
 990                               struct Qdisc *qdisc)
 991 {
 992         struct Qdisc *oqdisc = dev_queue->qdisc_sleeping;
 993         spinlock_t *root_lock;
 994
 995         root_lock = qdisc_lock(oqdisc);
 996         spin_lock_bh(root_lock);
 997
 998         /* ... and graft new one */
 999         if (qdisc == NULL)
1000                 qdisc = &noop_qdisc;
1001         dev_queue->qdisc_sleeping = qdisc;
1002         rcu_assign_pointer(dev_queue->qdisc, &noop_qdisc);
1003
1004         spin_unlock_bh(root_lock);
1005
1006         return oqdisc;
1007 }
1008 EXPORT_SYMBOL(dev_graft_qdisc);
1009
1010 static void attach_one_default_qdisc(struct net_device *dev,
1011                                      struct netdev_queue *dev_queue,
1012                                      void *_unused)
1013 {
1014         struct Qdisc *qdisc;
1015         const struct Qdisc_ops *ops = default_qdisc_ops;
1016
1017         if (dev->priv_flags & IFF_NO_QUEUE)
1018                 ops = &noqueue_qdisc_ops;
1019
1020         qdisc = qdisc_create_dflt(dev_queue, ops, TC_H_ROOT, NULL);
1021         if (!qdisc) {
1022                 netdev_info(dev, "activation failed\n");
1023                 return;
1024         }
1025         if (!netif_is_multiqueue(dev))
1026                 qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
1027         dev_queue->qdisc_sleeping = qdisc;
1028 }
1029
1030 static void attach_default_qdiscs(struct net_device *dev)
1031 {
1032         struct netdev_queue *txq;
1033         struct Qdisc *qdisc;
1034
1035         txq = netdev_get_tx_queue(dev, 0);
1036
1037         if (!netif_is_multiqueue(dev) ||
1038             dev->priv_flags & IFF_NO_QUEUE) {
1039                 netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
1040                 dev->qdisc = txq->qdisc_sleeping;
1041                 qdisc_refcount_inc(dev->qdisc);
1042         } else {
1043                 qdisc = qdisc_create_dflt(txq, &mq_qdisc_ops, TC_H_ROOT, NULL);
1044                 if (qdisc) {
1045                         dev->qdisc = qdisc;
1046                         qdisc->ops->attach(qdisc);
1047                 }
1048         }
1049 #ifdef CONFIG_NET_SCHED
1050         if (dev->qdisc != &noop_qdisc)
1051                 qdisc_hash_add(dev->qdisc, false);
1052 #endif
1053 }
1054
1055 static void transition_one_qdisc(struct net_device *dev,
1056                                  struct netdev_queue *dev_queue,
1057                                  void *_need_watchdog)
1058 {
1059         struct Qdisc *new_qdisc = dev_queue->qdisc_sleeping;
1060         int *need_watchdog_p = _need_watchdog;
1061
1062         if (!(new_qdisc->flags & TCQ_F_BUILTIN))
1063                 clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state);
1064
1065         rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
1066         if (need_watchdog_p) {
1067                 dev_queue->trans_start = 0;
1068                 *need_watchdog_p = 1;
1069         }
1070 }
1071
1072 void dev_activate(struct net_device *dev)
1073 {
1074         int need_watchdog;
1075
1076         /* No queueing discipline is attached to device;
1077          * create default one for devices, which need queueing
1078          * and noqueue_qdisc for virtual interfaces
1079          */
1080
1081         if (dev->qdisc == &noop_qdisc)
1082                 attach_default_qdiscs(dev);
1083
1084         if (!netif_carrier_ok(dev))
1085                 /* Delay activation until next carrier-on event */
1086                 return;
1087
1088         need_watchdog = 0;
1089         netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
1090         if (dev_ingress_queue(dev))
1091                 transition_one_qdisc(dev, dev_ingress_queue(dev), NULL);
1092
1093         if (need_watchdog) {
1094                 netif_trans_update(dev);
1095                 dev_watchdog_up(dev);
1096         }
1097 }
1098 EXPORT_SYMBOL(dev_activate);
1099
1100 static void dev_deactivate_queue(struct net_device *dev,
1101                                  struct netdev_queue *dev_queue,
1102                                  void *_qdisc_default)
1103 {
1104         struct Qdisc *qdisc_default = _qdisc_default;
1105         struct Qdisc *qdisc;
1106
1107         qdisc = rtnl_dereference(dev_queue->qdisc);
1108         if (qdisc) {
1109                 spin_lock_bh(qdisc_lock(qdisc));
1110
1111                 if (!(qdisc->flags & TCQ_F_BUILTIN))
1112                         set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
1113
1114                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
1115                 qdisc_reset(qdisc);
1116
1117                 spin_unlock_bh(qdisc_lock(qdisc));
1118         }
1119 }
1120
1121 static bool some_qdisc_is_busy(struct net_device *dev)
1122 {
1123         unsigned int i;
1124
1125         for (i = 0; i < dev->num_tx_queues; i++) {
1126                 struct netdev_queue *dev_queue;
1127                 spinlock_t *root_lock;
1128                 struct Qdisc *q;
1129                 int val;
1130
1131                 dev_queue = netdev_get_tx_queue(dev, i);
1132                 q = dev_queue->qdisc_sleeping;
1133
1134                 if (q->flags & TCQ_F_NOLOCK) {
1135                         val = test_bit(__QDISC_STATE_SCHED, &q->state);
1136                 } else {
1137                         root_lock = qdisc_lock(q);
1138                         spin_lock_bh(root_lock);
1139
1140                         val = (qdisc_is_running(q) ||
1141                                test_bit(__QDISC_STATE_SCHED, &q->state));
1142
1143                         spin_unlock_bh(root_lock);
1144                 }
1145
1146                 if (val)
1147                         return true;
1148         }
1149         return false;
1150 }
1151
1152 static void dev_qdisc_reset(struct net_device *dev,
1153                             struct netdev_queue *dev_queue,
1154                             void *none)
1155 {
1156         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
1157
1158         if (qdisc)
1159                 qdisc_reset(qdisc);
1160 }
1161
1162 /**
1163  *      dev_deactivate_many - deactivate transmissions on several devices
1164  *      @head: list of devices to deactivate
1165  *
1166  *      This function returns only when all outstanding transmissions
1167  *      have completed, unless all devices are in dismantle phase.
1168  */
1169 void dev_deactivate_many(struct list_head *head)
1170 {
1171         struct net_device *dev;
1172
1173         list_for_each_entry(dev, head, close_list) {
1174                 netdev_for_each_tx_queue(dev, dev_deactivate_queue,
1175                                          &noop_qdisc);
1176                 if (dev_ingress_queue(dev))
1177                         dev_deactivate_queue(dev, dev_ingress_queue(dev),
1178                                              &noop_qdisc);
1179
1180                 dev_watchdog_down(dev);
1181         }
1182
1183         /* Wait for outstanding qdisc-less dev_queue_xmit calls.
1184          * This is avoided if all devices are in dismantle phase :
1185          * Caller will call synchronize_net() for us
1186          */
1187         synchronize_net();
1188
1189         /* Wait for outstanding qdisc_run calls. */
1190         list_for_each_entry(dev, head, close_list) {
1191                 while (some_qdisc_is_busy(dev))
1192                         yield();
1193                 /* The new qdisc is assigned at this point so we can safely
1194                  * unwind stale skb lists and qdisc statistics
1195                  */
1196                 netdev_for_each_tx_queue(dev, dev_qdisc_reset, NULL);
1197                 if (dev_ingress_queue(dev))
1198                         dev_qdisc_reset(dev, dev_ingress_queue(dev), NULL);
1199         }
1200 }
1201
1202 void dev_deactivate(struct net_device *dev)
1203 {
1204         LIST_HEAD(single);
1205
1206         list_add(&dev->close_list, &single);
1207         dev_deactivate_many(&single);
1208         list_del(&single);
1209 }
1210 EXPORT_SYMBOL(dev_deactivate);
1211
1212 static int qdisc_change_tx_queue_len(struct net_device *dev,
1213                                      struct netdev_queue *dev_queue)
1214 {
1215         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
1216         const struct Qdisc_ops *ops = qdisc->ops;
1217
1218         if (ops->change_tx_queue_len)
1219                 return ops->change_tx_queue_len(qdisc, dev->tx_queue_len);
1220         return 0;
1221 }
1222
1223 int dev_qdisc_change_tx_queue_len(struct net_device *dev)
1224 {
1225         bool up = dev->flags & IFF_UP;
1226         unsigned int i;
1227         int ret = 0;
1228
1229         if (up)
1230                 dev_deactivate(dev);
1231
1232         for (i = 0; i < dev->num_tx_queues; i++) {
1233                 ret = qdisc_change_tx_queue_len(dev, &dev->_tx[i]);
1234
1235                 /* TODO: revert changes on a partial failure */
1236                 if (ret)
1237                         break;
1238         }
1239
1240         if (up)
1241                 dev_activate(dev);
1242         return ret;
1243 }
1244
1245 static void dev_init_scheduler_queue(struct net_device *dev,
1246                                      struct netdev_queue *dev_queue,
1247                                      void *_qdisc)
1248 {
1249         struct Qdisc *qdisc = _qdisc;
1250
1251         rcu_assign_pointer(dev_queue->qdisc, qdisc);
1252         dev_queue->qdisc_sleeping = qdisc;
1253         __skb_queue_head_init(&qdisc->gso_skb);
1254         __skb_queue_head_init(&qdisc->skb_bad_txq);
1255 }
1256
1257 void dev_init_scheduler(struct net_device *dev)
1258 {
1259         dev->qdisc = &noop_qdisc;
1260         netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
1261         if (dev_ingress_queue(dev))
1262                 dev_init_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
1263
1264         timer_setup(&dev->watchdog_timer, dev_watchdog, 0);
1265 }
1266
1267 static void shutdown_scheduler_queue(struct net_device *dev,
1268                                      struct netdev_queue *dev_queue,
1269                                      void *_qdisc_default)
1270 {
1271         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
1272         struct Qdisc *qdisc_default = _qdisc_default;
1273
1274         if (qdisc) {
1275                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
1276                 dev_queue->qdisc_sleeping = qdisc_default;
1277
1278                 qdisc_destroy(qdisc);
1279         }
1280 }
1281
1282 void dev_shutdown(struct net_device *dev)
1283 {
1284         netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
1285         if (dev_ingress_queue(dev))
1286                 shutdown_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
1287         qdisc_destroy(dev->qdisc);
1288         dev->qdisc = &noop_qdisc;
1289
1290         WARN_ON(timer_pending(&dev->watchdog_timer));
1291 }
1292
1293 void psched_ratecfg_precompute(struct psched_ratecfg *r,
1294                                const struct tc_ratespec *conf,
1295                                u64 rate64)
1296 {
1297         memset(r, 0, sizeof(*r));
1298         r->overhead = conf->overhead;
1299         r->rate_bytes_ps = max_t(u64, conf->rate, rate64);
1300         r->linklayer = (conf->linklayer & TC_LINKLAYER_MASK);
1301         r->mult = 1;
1302         /*
1303          * The deal here is to replace a divide by a reciprocal one
1304          * in fast path (a reciprocal divide is a multiply and a shift)
1305          *
1306          * Normal formula would be :
1307          *  time_in_ns = (NSEC_PER_SEC * len) / rate_bps
1308          *
1309          * We compute mult/shift to use instead :
1310          *  time_in_ns = (len * mult) >> shift;
1311          *
1312          * We try to get the highest possible mult value for accuracy,
1313          * but have to make sure no overflows will ever happen.
1314          */
1315         if (r->rate_bytes_ps > 0) {
1316                 u64 factor = NSEC_PER_SEC;
1317
1318                 for (;;) {
1319                         r->mult = div64_u64(factor, r->rate_bytes_ps);
1320                         if (r->mult & (1U << 31) || factor & (1ULL << 63))
1321                                 break;
1322                         factor <<= 1;
1323                         r->shift++;
1324                 }
1325         }
1326 }
1327 EXPORT_SYMBOL(psched_ratecfg_precompute);
1328
1329 static void mini_qdisc_rcu_func(struct rcu_head *head)
1330 {
1331 }
1332
1333 void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp,
1334                           struct tcf_proto *tp_head)
1335 {
1336         struct mini_Qdisc *miniq_old = rtnl_dereference(*miniqp->p_miniq);
1337         struct mini_Qdisc *miniq;
1338
1339         if (!tp_head) {
1340                 RCU_INIT_POINTER(*miniqp->p_miniq, NULL);
1341                 /* Wait for flying RCU callback before it is freed. */
1342                 rcu_barrier_bh();
1343                 return;
1344         }
1345
1346         miniq = !miniq_old || miniq_old == &miniqp->miniq2 ?
1347                 &miniqp->miniq1 : &miniqp->miniq2;
1348
1349         /* We need to make sure that readers won't see the miniq
1350          * we are about to modify. So wait until previous call_rcu_bh callback
1351          * is done.
1352          */
1353         rcu_barrier_bh();
1354         miniq->filter_list = tp_head;
1355         rcu_assign_pointer(*miniqp->p_miniq, miniq);
1356
1357         if (miniq_old)
1358                 /* This is counterpart of the rcu barriers above. We need to
1359                  * block potential new user of miniq_old until all readers
1360                  * are not seeing it.
1361                  */
1362                 call_rcu_bh(&miniq_old->rcu, mini_qdisc_rcu_func);
1363 }
1364 EXPORT_SYMBOL(mini_qdisc_pair_swap);
1365
1366 void mini_qdisc_pair_init(struct mini_Qdisc_pair *miniqp, struct Qdisc *qdisc,
1367                           struct mini_Qdisc __rcu **p_miniq)
1368 {
1369         miniqp->miniq1.cpu_bstats = qdisc->cpu_bstats;
1370         miniqp->miniq1.cpu_qstats = qdisc->cpu_qstats;
1371         miniqp->miniq2.cpu_bstats = qdisc->cpu_bstats;
1372         miniqp->miniq2.cpu_qstats = qdisc->cpu_qstats;
1373         miniqp->p_miniq = p_miniq;
1374 }
1375 EXPORT_SYMBOL(mini_qdisc_pair_init);