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 void dev_requeue_skb(struct sk_buff *skb, struct Qdisc *q)
 122 {
 123         spinlock_t *lock = NULL;
 124
 125         if (q->flags & TCQ_F_NOLOCK) {
 126                 lock = qdisc_lock(q);
 127                 spin_lock(lock);
 128         }
 129
 130         while (skb) {
 131                 struct sk_buff *next = skb->next;
 132
 133                 __skb_queue_tail(&q->gso_skb, skb);
 134
 135                 /* it's still part of the queue */
 136                 if (qdisc_is_percpu_stats(q)) {
 137                         qdisc_qstats_cpu_requeues_inc(q);
 138                         qdisc_qstats_cpu_backlog_inc(q, skb);
 139                         qdisc_qstats_cpu_qlen_inc(q);
 140                 } else {
 141                         q->qstats.requeues++;
 142                         qdisc_qstats_backlog_inc(q, skb);
 143                         q->q.qlen++;
 144                 }
 145
 146                 skb = next;
 147         }
 148         if (lock)
 149                 spin_unlock(lock);
 150         __netif_schedule(q);
 151 }
 152
 153 static void try_bulk_dequeue_skb(struct Qdisc *q,
 154                                  struct sk_buff *skb,
 155                                  const struct netdev_queue *txq,
 156                                  int *packets)
 157 {
 158         int bytelimit = qdisc_avail_bulklimit(txq) - skb->len;
 159
 160         while (bytelimit > 0) {
 161                 struct sk_buff *nskb = q->dequeue(q);
 162
 163                 if (!nskb)
 164                         break;
 165
 166                 bytelimit -= nskb->len; /* covers GSO len */
 167                 skb->next = nskb;
 168                 skb = nskb;
 169                 (*packets)++; /* GSO counts as one pkt */
 170         }
 171         skb_mark_not_on_list(skb);
 172 }
 173
 174 /* This variant of try_bulk_dequeue_skb() makes sure
 175  * all skbs in the chain are for the same txq
 176  */
 177 static void try_bulk_dequeue_skb_slow(struct Qdisc *q,
 178                                       struct sk_buff *skb,
 179                                       int *packets)
 180 {
 181         int mapping = skb_get_queue_mapping(skb);
 182         struct sk_buff *nskb;
 183         int cnt = 0;
 184
 185         do {
 186                 nskb = q->dequeue(q);
 187                 if (!nskb)
 188                         break;
 189                 if (unlikely(skb_get_queue_mapping(nskb) != mapping)) {
 190                         qdisc_enqueue_skb_bad_txq(q, nskb);
 191                         break;
 192                 }
 193                 skb->next = nskb;
 194                 skb = nskb;
 195         } while (++cnt < 8);
 196         (*packets) += cnt;
 197         skb_mark_not_on_list(skb);
 198 }
 199
 200 /* Note that dequeue_skb can possibly return a SKB list (via skb->next).
 201  * A requeued skb (via q->gso_skb) can also be a SKB list.
 202  */
 203 static struct sk_buff *dequeue_skb(struct Qdisc *q, bool *validate,
 204                                    int *packets)
 205 {
 206         const struct netdev_queue *txq = q->dev_queue;
 207         struct sk_buff *skb = NULL;
 208
 209         *packets = 1;
 210         if (unlikely(!skb_queue_empty(&q->gso_skb))) {
 211                 spinlock_t *lock = NULL;
 212
 213                 if (q->flags & TCQ_F_NOLOCK) {
 214                         lock = qdisc_lock(q);
 215                         spin_lock(lock);
 216                 }
 217
 218                 skb = skb_peek(&q->gso_skb);
 219
 220                 /* skb may be null if another cpu pulls gso_skb off in between
 221                  * empty check and lock.
 222                  */
 223                 if (!skb) {
 224                         if (lock)
 225                                 spin_unlock(lock);
 226                         goto validate;
 227                 }
 228
 229                 /* skb in gso_skb were already validated */
 230                 *validate = false;
 231                 if (xfrm_offload(skb))
 232                         *validate = true;
 233                 /* check the reason of requeuing without tx lock first */
 234                 txq = skb_get_tx_queue(txq->dev, skb);
 235                 if (!netif_xmit_frozen_or_stopped(txq)) {
 236                         skb = __skb_dequeue(&q->gso_skb);
 237                         if (qdisc_is_percpu_stats(q)) {
 238                                 qdisc_qstats_cpu_backlog_dec(q, skb);
 239                                 qdisc_qstats_cpu_qlen_dec(q);
 240                         } else {
 241                                 qdisc_qstats_backlog_dec(q, skb);
 242                                 q->q.qlen--;
 243                         }
 244                 } else {
 245                         skb = NULL;
 246                 }
 247                 if (lock)
 248                         spin_unlock(lock);
 249                 goto trace;
 250         }
 251 validate:
 252         *validate = true;
 253
 254         if ((q->flags & TCQ_F_ONETXQUEUE) &&
 255             netif_xmit_frozen_or_stopped(txq))
 256                 return skb;
 257
 258         skb = qdisc_dequeue_skb_bad_txq(q);
 259         if (unlikely(skb))
 260                 goto bulk;
 261         skb = q->dequeue(q);
 262         if (skb) {
 263 bulk:
 264                 if (qdisc_may_bulk(q))
 265                         try_bulk_dequeue_skb(q, skb, txq, packets);
 266                 else
 267                         try_bulk_dequeue_skb_slow(q, skb, packets);
 268         }
 269 trace:
 270         trace_qdisc_dequeue(q, txq, *packets, skb);
 271         return skb;
 272 }
 273
 274 /*
 275  * Transmit possibly several skbs, and handle the return status as
 276  * required. Owning running seqcount bit guarantees that
 277  * only one CPU can execute this function.
 278  *
 279  * Returns to the caller:
 280  *                              false  - hardware queue frozen backoff
 281  *                              true   - feel free to send more pkts
 282  */
 283 bool sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
 284                      struct net_device *dev, struct netdev_queue *txq,
 285                      spinlock_t *root_lock, bool validate)
 286 {
 287         int ret = NETDEV_TX_BUSY;
 288         bool again = false;
 289
 290         /* And release qdisc */
 291         if (root_lock)
 292                 spin_unlock(root_lock);
 293
 294         /* Note that we validate skb (GSO, checksum, ...) outside of locks */
 295         if (validate)
 296                 skb = validate_xmit_skb_list(skb, dev, &again);
 297
 298 #ifdef CONFIG_XFRM_OFFLOAD
 299         if (unlikely(again)) {
 300                 if (root_lock)
 301                         spin_lock(root_lock);
 302
 303                 dev_requeue_skb(skb, q);
 304                 return false;
 305         }
 306 #endif
 307
 308         if (likely(skb)) {
 309                 HARD_TX_LOCK(dev, txq, smp_processor_id());
 310                 if (!netif_xmit_frozen_or_stopped(txq))
 311                         skb = dev_hard_start_xmit(skb, dev, txq, &ret);
 312
 313                 HARD_TX_UNLOCK(dev, txq);
 314         } else {
 315                 if (root_lock)
 316                         spin_lock(root_lock);
 317                 return true;
 318         }
 319
 320         if (root_lock)
 321                 spin_lock(root_lock);
 322
 323         if (!dev_xmit_complete(ret)) {
 324                 /* Driver returned NETDEV_TX_BUSY - requeue skb */
 325                 if (unlikely(ret != NETDEV_TX_BUSY))
 326                         net_warn_ratelimited("BUG %s code %d qlen %d\n",
 327                                              dev->name, ret, q->q.qlen);
 328
 329                 dev_requeue_skb(skb, q);
 330                 return false;
 331         }
 332
 333         return true;
 334 }
 335
 336 /*
 337  * NOTE: Called under qdisc_lock(q) with locally disabled BH.
 338  *
 339  * running seqcount guarantees only one CPU can process
 340  * this qdisc at a time. qdisc_lock(q) serializes queue accesses for
 341  * this queue.
 342  *
 343  *  netif_tx_lock serializes accesses to device driver.
 344  *
 345  *  qdisc_lock(q) and netif_tx_lock are mutually exclusive,
 346  *  if one is grabbed, another must be free.
 347  *
 348  * Note, that this procedure can be called by a watchdog timer
 349  *
 350  * Returns to the caller:
 351  *                              0  - queue is empty or throttled.
 352  *                              >0 - queue is not empty.
 353  *
 354  */
 355 static inline bool qdisc_restart(struct Qdisc *q, int *packets)
 356 {
 357         spinlock_t *root_lock = NULL;
 358         struct netdev_queue *txq;
 359         struct net_device *dev;
 360         struct sk_buff *skb;
 361         bool validate;
 362
 363         /* Dequeue packet */
 364         skb = dequeue_skb(q, &validate, packets);
 365         if (unlikely(!skb))
 366                 return false;
 367
 368         if (!(q->flags & TCQ_F_NOLOCK))
 369                 root_lock = qdisc_lock(q);
 370
 371         dev = qdisc_dev(q);
 372         txq = skb_get_tx_queue(dev, skb);
 373
 374         return sch_direct_xmit(skb, q, dev, txq, root_lock, validate);
 375 }
 376
 377 void __qdisc_run(struct Qdisc *q)
 378 {
 379         int quota = dev_tx_weight;
 380         int packets;
 381
 382         while (qdisc_restart(q, &packets)) {
 383                 /*
 384                  * Ordered by possible occurrence: Postpone processing if
 385                  * 1. we've exceeded packet quota
 386                  * 2. another process needs the CPU;
 387                  */
 388                 quota -= packets;
 389                 if (quota <= 0 || need_resched()) {
 390                         __netif_schedule(q);
 391                         break;
 392                 }
 393         }
 394 }
 395
 396 unsigned long dev_trans_start(struct net_device *dev)
 397 {
 398         unsigned long val, res;
 399         unsigned int i;
 400
 401         if (is_vlan_dev(dev))
 402                 dev = vlan_dev_real_dev(dev);
 403         else if (netif_is_macvlan(dev))
 404                 dev = macvlan_dev_real_dev(dev);
 405         res = netdev_get_tx_queue(dev, 0)->trans_start;
 406         for (i = 1; i < dev->num_tx_queues; i++) {
 407                 val = netdev_get_tx_queue(dev, i)->trans_start;
 408                 if (val && time_after(val, res))
 409                         res = val;
 410         }
 411
 412         return res;
 413 }
 414 EXPORT_SYMBOL(dev_trans_start);
 415
 416 static void dev_watchdog(struct timer_list *t)
 417 {
 418         struct net_device *dev = from_timer(dev, t, watchdog_timer);
 419
 420         netif_tx_lock(dev);
 421         if (!qdisc_tx_is_noop(dev)) {
 422                 if (netif_device_present(dev) &&
 423                     netif_running(dev) &&
 424                     netif_carrier_ok(dev)) {
 425                         int some_queue_timedout = 0;
 426                         unsigned int i;
 427                         unsigned long trans_start;
 428
 429                         for (i = 0; i < dev->num_tx_queues; i++) {
 430                                 struct netdev_queue *txq;
 431
 432                                 txq = netdev_get_tx_queue(dev, i);
 433                                 trans_start = txq->trans_start;
 434                                 if (netif_xmit_stopped(txq) &&
 435                                     time_after(jiffies, (trans_start +
 436                                                          dev->watchdog_timeo))) {
 437                                         some_queue_timedout = 1;
 438                                         txq->trans_timeout++;
 439                                         break;
 440                                 }
 441                         }
 442
 443                         if (some_queue_timedout) {
 444                                 WARN_ONCE(1, KERN_INFO "NETDEV WATCHDOG: %s (%s): transmit queue %u timed out\n",
 445                                        dev->name, netdev_drivername(dev), i);
 446                                 dev->netdev_ops->ndo_tx_timeout(dev);
 447                         }
 448                         if (!mod_timer(&dev->watchdog_timer,
 449                                        round_jiffies(jiffies +
 450                                                      dev->watchdog_timeo)))
 451                                 dev_hold(dev);
 452                 }
 453         }
 454         netif_tx_unlock(dev);
 455
 456         dev_put(dev);
 457 }
 458
 459 void __netdev_watchdog_up(struct net_device *dev)
 460 {
 461         if (dev->netdev_ops->ndo_tx_timeout) {
 462                 if (dev->watchdog_timeo <= 0)
 463                         dev->watchdog_timeo = 5*HZ;
 464                 if (!mod_timer(&dev->watchdog_timer,
 465                                round_jiffies(jiffies + dev->watchdog_timeo)))
 466                         dev_hold(dev);
 467         }
 468 }
 469
 470 static void dev_watchdog_up(struct net_device *dev)
 471 {
 472         __netdev_watchdog_up(dev);
 473 }
 474
 475 static void dev_watchdog_down(struct net_device *dev)
 476 {
 477         netif_tx_lock_bh(dev);
 478         if (del_timer(&dev->watchdog_timer))
 479                 dev_put(dev);
 480         netif_tx_unlock_bh(dev);
 481 }
 482
 483 /**
 484  *      netif_carrier_on - set carrier
 485  *      @dev: network device
 486  *
 487  * Device has detected acquisition of carrier.
 488  */
 489 void netif_carrier_on(struct net_device *dev)
 490 {
 491         if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
 492                 if (dev->reg_state == NETREG_UNINITIALIZED)
 493                         return;
 494                 atomic_inc(&dev->carrier_up_count);
 495                 linkwatch_fire_event(dev);
 496                 if (netif_running(dev))
 497                         __netdev_watchdog_up(dev);
 498         }
 499 }
 500 EXPORT_SYMBOL(netif_carrier_on);
 501
 502 /**
 503  *      netif_carrier_off - clear carrier
 504  *      @dev: network device
 505  *
 506  * Device has detected loss of carrier.
 507  */
 508 void netif_carrier_off(struct net_device *dev)
 509 {
 510         if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
 511                 if (dev->reg_state == NETREG_UNINITIALIZED)
 512                         return;
 513                 atomic_inc(&dev->carrier_down_count);
 514                 linkwatch_fire_event(dev);
 515         }
 516 }
 517 EXPORT_SYMBOL(netif_carrier_off);
 518
 519 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
 520    under all circumstances. It is difficult to invent anything faster or
 521    cheaper.
 522  */
 523
 524 static int noop_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
 525                         struct sk_buff **to_free)
 526 {
 527         __qdisc_drop(skb, to_free);
 528         return NET_XMIT_CN;
 529 }
 530
 531 static struct sk_buff *noop_dequeue(struct Qdisc *qdisc)
 532 {
 533         return NULL;
 534 }
 535
 536 struct Qdisc_ops noop_qdisc_ops __read_mostly = {
 537         .id             =       "noop",
 538         .priv_size      =       0,
 539         .enqueue        =       noop_enqueue,
 540         .dequeue        =       noop_dequeue,
 541         .peek           =       noop_dequeue,
 542         .owner          =       THIS_MODULE,
 543 };
 544
 545 static struct netdev_queue noop_netdev_queue = {
 546         RCU_POINTER_INITIALIZER(qdisc, &noop_qdisc),
 547         .qdisc_sleeping =       &noop_qdisc,
 548 };
 549
 550 struct Qdisc noop_qdisc = {
 551         .enqueue        =       noop_enqueue,
 552         .dequeue        =       noop_dequeue,
 553         .flags          =       TCQ_F_BUILTIN,
 554         .ops            =       &noop_qdisc_ops,
 555         .q.lock         =       __SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
 556         .dev_queue      =       &noop_netdev_queue,
 557         .running        =       SEQCNT_ZERO(noop_qdisc.running),
 558         .busylock       =       __SPIN_LOCK_UNLOCKED(noop_qdisc.busylock),
 559         .gso_skb = {
 560                 .next = (struct sk_buff *)&noop_qdisc.gso_skb,
 561                 .prev = (struct sk_buff *)&noop_qdisc.gso_skb,
 562                 .qlen = 0,
 563                 .lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.gso_skb.lock),
 564         },
 565         .skb_bad_txq = {
 566                 .next = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
 567                 .prev = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
 568                 .qlen = 0,
 569                 .lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.skb_bad_txq.lock),
 570         },
 571 };
 572 EXPORT_SYMBOL(noop_qdisc);
 573
 574 static int noqueue_init(struct Qdisc *qdisc, struct nlattr *opt,
 575                         struct netlink_ext_ack *extack)
 576 {
 577         /* register_qdisc() assigns a default of noop_enqueue if unset,
 578          * but __dev_queue_xmit() treats noqueue only as such
 579          * if this is NULL - so clear it here. */
 580         qdisc->enqueue = NULL;
 581         return 0;
 582 }
 583
 584 struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
 585         .id             =       "noqueue",
 586         .priv_size      =       0,
 587         .init           =       noqueue_init,
 588         .enqueue        =       noop_enqueue,
 589         .dequeue        =       noop_dequeue,
 590         .peek           =       noop_dequeue,
 591         .owner          =       THIS_MODULE,
 592 };
 593
 594 static const u8 prio2band[TC_PRIO_MAX + 1] = {
 595         1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1
 596 };
 597
 598 /* 3-band FIFO queue: old style, but should be a bit faster than
 599    generic prio+fifo combination.
 600  */
 601
 602 #define PFIFO_FAST_BANDS 3
 603
 604 /*
 605  * Private data for a pfifo_fast scheduler containing:
 606  *      - rings for priority bands
 607  */
 608 struct pfifo_fast_priv {
 609         struct skb_array q[PFIFO_FAST_BANDS];
 610 };
 611
 612 static inline struct skb_array *band2list(struct pfifo_fast_priv *priv,
 613                                           int band)
 614 {
 615         return &priv->q[band];
 616 }
 617
 618 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
 619                               struct sk_buff **to_free)
 620 {
 621         int band = prio2band[skb->priority & TC_PRIO_MAX];
 622         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 623         struct skb_array *q = band2list(priv, band);
 624         unsigned int pkt_len = qdisc_pkt_len(skb);
 625         int err;
 626
 627         err = skb_array_produce(q, skb);
 628
 629         if (unlikely(err))
 630                 return qdisc_drop_cpu(skb, qdisc, to_free);
 631
 632         qdisc_update_stats_at_enqueue(qdisc, pkt_len);
 633         return NET_XMIT_SUCCESS;
 634 }
 635
 636 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc *qdisc)
 637 {
 638         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 639         struct sk_buff *skb = NULL;
 640         int band;
 641
 642         for (band = 0; band < PFIFO_FAST_BANDS && !skb; band++) {
 643                 struct skb_array *q = band2list(priv, band);
 644
 645                 if (__skb_array_empty(q))
 646                         continue;
 647
 648                 skb = __skb_array_consume(q);
 649         }
 650         if (likely(skb)) {
 651                 qdisc_update_stats_at_dequeue(qdisc, skb);
 652         } else {
 653                 qdisc->empty = true;
 654         }
 655
 656         return skb;
 657 }
 658
 659 static struct sk_buff *pfifo_fast_peek(struct Qdisc *qdisc)
 660 {
 661         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 662         struct sk_buff *skb = NULL;
 663         int band;
 664
 665         for (band = 0; band < PFIFO_FAST_BANDS && !skb; band++) {
 666                 struct skb_array *q = band2list(priv, band);
 667
 668                 skb = __skb_array_peek(q);
 669         }
 670
 671         return skb;
 672 }
 673
 674 static void pfifo_fast_reset(struct Qdisc *qdisc)
 675 {
 676         int i, band;
 677         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 678
 679         for (band = 0; band < PFIFO_FAST_BANDS; band++) {
 680                 struct skb_array *q = band2list(priv, band);
 681                 struct sk_buff *skb;
 682
 683                 /* NULL ring is possible if destroy path is due to a failed
 684                  * skb_array_init() in pfifo_fast_init() case.
 685                  */
 686                 if (!q->ring.queue)
 687                         continue;
 688
 689                 while ((skb = __skb_array_consume(q)) != NULL)
 690                         kfree_skb(skb);
 691         }
 692
 693         for_each_possible_cpu(i) {
 694                 struct gnet_stats_queue *q = per_cpu_ptr(qdisc->cpu_qstats, i);
 695
 696                 q->backlog = 0;
 697                 q->qlen = 0;
 698         }
 699 }
 700
 701 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
 702 {
 703         struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
 704
 705         memcpy(&opt.priomap, prio2band, TC_PRIO_MAX + 1);
 706         if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
 707                 goto nla_put_failure;
 708         return skb->len;
 709
 710 nla_put_failure:
 711         return -1;
 712 }
 713
 714 static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt,
 715                            struct netlink_ext_ack *extack)
 716 {
 717         unsigned int qlen = qdisc_dev(qdisc)->tx_queue_len;
 718         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 719         int prio;
 720
 721         /* guard against zero length rings */
 722         if (!qlen)
 723                 return -EINVAL;
 724
 725         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
 726                 struct skb_array *q = band2list(priv, prio);
 727                 int err;
 728
 729                 err = skb_array_init(q, qlen, GFP_KERNEL);
 730                 if (err)
 731                         return -ENOMEM;
 732         }
 733
 734         /* Can by-pass the queue discipline */
 735         qdisc->flags |= TCQ_F_CAN_BYPASS;
 736         return 0;
 737 }
 738
 739 static void pfifo_fast_destroy(struct Qdisc *sch)
 740 {
 741         struct pfifo_fast_priv *priv = qdisc_priv(sch);
 742         int prio;
 743
 744         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
 745                 struct skb_array *q = band2list(priv, prio);
 746
 747                 /* NULL ring is possible if destroy path is due to a failed
 748                  * skb_array_init() in pfifo_fast_init() case.
 749                  */
 750                 if (!q->ring.queue)
 751                         continue;
 752                 /* Destroy ring but no need to kfree_skb because a call to
 753                  * pfifo_fast_reset() has already done that work.
 754                  */
 755                 ptr_ring_cleanup(&q->ring, NULL);
 756         }
 757 }
 758
 759 static int pfifo_fast_change_tx_queue_len(struct Qdisc *sch,
 760                                           unsigned int new_len)
 761 {
 762         struct pfifo_fast_priv *priv = qdisc_priv(sch);
 763         struct skb_array *bands[PFIFO_FAST_BANDS];
 764         int prio;
 765
 766         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
 767                 struct skb_array *q = band2list(priv, prio);
 768
 769                 bands[prio] = q;
 770         }
 771
 772         return skb_array_resize_multiple(bands, PFIFO_FAST_BANDS, new_len,
 773                                          GFP_KERNEL);
 774 }
 775
 776 struct Qdisc_ops pfifo_fast_ops __read_mostly = {
 777         .id             =       "pfifo_fast",
 778         .priv_size      =       sizeof(struct pfifo_fast_priv),
 779         .enqueue        =       pfifo_fast_enqueue,
 780         .dequeue        =       pfifo_fast_dequeue,
 781         .peek           =       pfifo_fast_peek,
 782         .init           =       pfifo_fast_init,
 783         .destroy        =       pfifo_fast_destroy,
 784         .reset          =       pfifo_fast_reset,
 785         .dump           =       pfifo_fast_dump,
 786         .change_tx_queue_len =  pfifo_fast_change_tx_queue_len,
 787         .owner          =       THIS_MODULE,
 788         .static_flags   =       TCQ_F_NOLOCK | TCQ_F_CPUSTATS,
 789 };
 790 EXPORT_SYMBOL(pfifo_fast_ops);
 791
 792 static struct lock_class_key qdisc_tx_busylock;
 793 static struct lock_class_key qdisc_running_key;
 794
 795 struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
 796                           const struct Qdisc_ops *ops,
 797                           struct netlink_ext_ack *extack)
 798 {
 799         void *p;
 800         struct Qdisc *sch;
 801         unsigned int size = QDISC_ALIGN(sizeof(*sch)) + ops->priv_size;
 802         int err = -ENOBUFS;
 803         struct net_device *dev;
 804
 805         if (!dev_queue) {
 806                 NL_SET_ERR_MSG(extack, "No device queue given");
 807                 err = -EINVAL;
 808                 goto errout;
 809         }
 810
 811         dev = dev_queue->dev;
 812         p = kzalloc_node(size, GFP_KERNEL,
 813                          netdev_queue_numa_node_read(dev_queue));
 814
 815         if (!p)
 816                 goto errout;
 817         sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
 818         /* if we got non aligned memory, ask more and do alignment ourself */
 819         if (sch != p) {
 820                 kfree(p);
 821                 p = kzalloc_node(size + QDISC_ALIGNTO - 1, GFP_KERNEL,
 822                                  netdev_queue_numa_node_read(dev_queue));
 823                 if (!p)
 824                         goto errout;
 825                 sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
 826                 sch->padded = (char *) sch - (char *) p;
 827         }
 828         __skb_queue_head_init(&sch->gso_skb);
 829         __skb_queue_head_init(&sch->skb_bad_txq);
 830         qdisc_skb_head_init(&sch->q);
 831         spin_lock_init(&sch->q.lock);
 832
 833         if (ops->static_flags & TCQ_F_CPUSTATS) {
 834                 sch->cpu_bstats =
 835                         netdev_alloc_pcpu_stats(struct gnet_stats_basic_cpu);
 836                 if (!sch->cpu_bstats)
 837                         goto errout1;
 838
 839                 sch->cpu_qstats = alloc_percpu(struct gnet_stats_queue);
 840                 if (!sch->cpu_qstats) {
 841                         free_percpu(sch->cpu_bstats);
 842                         goto errout1;
 843                 }
 844         }
 845
 846         spin_lock_init(&sch->busylock);
 847         lockdep_set_class(&sch->busylock,
 848                           dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
 849
 850         /* seqlock has the same scope of busylock, for NOLOCK qdisc */
 851         spin_lock_init(&sch->seqlock);
 852         lockdep_set_class(&sch->busylock,
 853                           dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
 854
 855         seqcount_init(&sch->running);
 856         lockdep_set_class(&sch->running,
 857                           dev->qdisc_running_key ?: &qdisc_running_key);
 858
 859         sch->ops = ops;
 860         sch->flags = ops->static_flags;
 861         sch->enqueue = ops->enqueue;
 862         sch->dequeue = ops->dequeue;
 863         sch->dev_queue = dev_queue;
 864         sch->empty = true;
 865         dev_hold(dev);
 866         refcount_set(&sch->refcnt, 1);
 867
 868         return sch;
 869 errout1:
 870         kfree(p);
 871 errout:
 872         return ERR_PTR(err);
 873 }
 874
 875 struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
 876                                 const struct Qdisc_ops *ops,
 877                                 unsigned int parentid,
 878                                 struct netlink_ext_ack *extack)
 879 {
 880         struct Qdisc *sch;
 881
 882         if (!try_module_get(ops->owner)) {
 883                 NL_SET_ERR_MSG(extack, "Failed to increase module reference counter");
 884                 return NULL;
 885         }
 886
 887         sch = qdisc_alloc(dev_queue, ops, extack);
 888         if (IS_ERR(sch)) {
 889                 module_put(ops->owner);
 890                 return NULL;
 891         }
 892         sch->parent = parentid;
 893
 894         if (!ops->init || ops->init(sch, NULL, extack) == 0)
 895                 return sch;
 896
 897         qdisc_put(sch);
 898         return NULL;
 899 }
 900 EXPORT_SYMBOL(qdisc_create_dflt);
 901
 902 /* Under qdisc_lock(qdisc) and BH! */
 903
 904 void qdisc_reset(struct Qdisc *qdisc)
 905 {
 906         const struct Qdisc_ops *ops = qdisc->ops;
 907         struct sk_buff *skb, *tmp;
 908
 909         if (ops->reset)
 910                 ops->reset(qdisc);
 911
 912         skb_queue_walk_safe(&qdisc->gso_skb, skb, tmp) {
 913                 __skb_unlink(skb, &qdisc->gso_skb);
 914                 kfree_skb_list(skb);
 915         }
 916
 917         skb_queue_walk_safe(&qdisc->skb_bad_txq, skb, tmp) {
 918                 __skb_unlink(skb, &qdisc->skb_bad_txq);
 919                 kfree_skb_list(skb);
 920         }
 921
 922         qdisc->q.qlen = 0;
 923         qdisc->qstats.backlog = 0;
 924 }
 925 EXPORT_SYMBOL(qdisc_reset);
 926
 927 void qdisc_free(struct Qdisc *qdisc)
 928 {
 929         if (qdisc_is_percpu_stats(qdisc)) {
 930                 free_percpu(qdisc->cpu_bstats);
 931                 free_percpu(qdisc->cpu_qstats);
 932         }
 933
 934         kfree((char *) qdisc - qdisc->padded);
 935 }
 936
 937 static void qdisc_free_cb(struct rcu_head *head)
 938 {
 939         struct Qdisc *q = container_of(head, struct Qdisc, rcu);
 940
 941         qdisc_free(q);
 942 }
 943
 944 static void qdisc_destroy(struct Qdisc *qdisc)
 945 {
 946         const struct Qdisc_ops  *ops = qdisc->ops;
 947         struct sk_buff *skb, *tmp;
 948
 949 #ifdef CONFIG_NET_SCHED
 950         qdisc_hash_del(qdisc);
 951
 952         qdisc_put_stab(rtnl_dereference(qdisc->stab));
 953 #endif
 954         gen_kill_estimator(&qdisc->rate_est);
 955         if (ops->reset)
 956                 ops->reset(qdisc);
 957         if (ops->destroy)
 958                 ops->destroy(qdisc);
 959
 960         module_put(ops->owner);
 961         dev_put(qdisc_dev(qdisc));
 962
 963         skb_queue_walk_safe(&qdisc->gso_skb, skb, tmp) {
 964                 __skb_unlink(skb, &qdisc->gso_skb);
 965                 kfree_skb_list(skb);
 966         }
 967
 968         skb_queue_walk_safe(&qdisc->skb_bad_txq, skb, tmp) {
 969                 __skb_unlink(skb, &qdisc->skb_bad_txq);
 970                 kfree_skb_list(skb);
 971         }
 972
 973         call_rcu(&qdisc->rcu, qdisc_free_cb);
 974 }
 975
 976 void qdisc_put(struct Qdisc *qdisc)
 977 {
 978         if (qdisc->flags & TCQ_F_BUILTIN ||
 979             !refcount_dec_and_test(&qdisc->refcnt))
 980                 return;
 981
 982         qdisc_destroy(qdisc);
 983 }
 984 EXPORT_SYMBOL(qdisc_put);
 985
 986 /* Version of qdisc_put() that is called with rtnl mutex unlocked.
 987  * Intended to be used as optimization, this function only takes rtnl lock if
 988  * qdisc reference counter reached zero.
 989  */
 990
 991 void qdisc_put_unlocked(struct Qdisc *qdisc)
 992 {
 993         if (qdisc->flags & TCQ_F_BUILTIN ||
 994             !refcount_dec_and_rtnl_lock(&qdisc->refcnt))
 995                 return;
 996
 997         qdisc_destroy(qdisc);
 998         rtnl_unlock();
 999 }
1000 EXPORT_SYMBOL(qdisc_put_unlocked);
1001
1002 /* Attach toplevel qdisc to device queue. */
1003 struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
1004                               struct Qdisc *qdisc)
1005 {
1006         struct Qdisc *oqdisc = dev_queue->qdisc_sleeping;
1007         spinlock_t *root_lock;
1008
1009         root_lock = qdisc_lock(oqdisc);
1010         spin_lock_bh(root_lock);
1011
1012         /* ... and graft new one */
1013         if (qdisc == NULL)
1014                 qdisc = &noop_qdisc;
1015         dev_queue->qdisc_sleeping = qdisc;
1016         rcu_assign_pointer(dev_queue->qdisc, &noop_qdisc);
1017
1018         spin_unlock_bh(root_lock);
1019
1020         return oqdisc;
1021 }
1022 EXPORT_SYMBOL(dev_graft_qdisc);
1023
1024 static void attach_one_default_qdisc(struct net_device *dev,
1025                                      struct netdev_queue *dev_queue,
1026                                      void *_unused)
1027 {
1028         struct Qdisc *qdisc;
1029         const struct Qdisc_ops *ops = default_qdisc_ops;
1030
1031         if (dev->priv_flags & IFF_NO_QUEUE)
1032                 ops = &noqueue_qdisc_ops;
1033
1034         qdisc = qdisc_create_dflt(dev_queue, ops, TC_H_ROOT, NULL);
1035         if (!qdisc) {
1036                 netdev_info(dev, "activation failed\n");
1037                 return;
1038         }
1039         if (!netif_is_multiqueue(dev))
1040                 qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
1041         dev_queue->qdisc_sleeping = qdisc;
1042 }
1043
1044 static void attach_default_qdiscs(struct net_device *dev)
1045 {
1046         struct netdev_queue *txq;
1047         struct Qdisc *qdisc;
1048
1049         txq = netdev_get_tx_queue(dev, 0);
1050
1051         if (!netif_is_multiqueue(dev) ||
1052             dev->priv_flags & IFF_NO_QUEUE) {
1053                 netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
1054                 dev->qdisc = txq->qdisc_sleeping;
1055                 qdisc_refcount_inc(dev->qdisc);
1056         } else {
1057                 qdisc = qdisc_create_dflt(txq, &mq_qdisc_ops, TC_H_ROOT, NULL);
1058                 if (qdisc) {
1059                         dev->qdisc = qdisc;
1060                         qdisc->ops->attach(qdisc);
1061                 }
1062         }
1063 #ifdef CONFIG_NET_SCHED
1064         if (dev->qdisc != &noop_qdisc)
1065                 qdisc_hash_add(dev->qdisc, false);
1066 #endif
1067 }
1068
1069 static void transition_one_qdisc(struct net_device *dev,
1070                                  struct netdev_queue *dev_queue,
1071                                  void *_need_watchdog)
1072 {
1073         struct Qdisc *new_qdisc = dev_queue->qdisc_sleeping;
1074         int *need_watchdog_p = _need_watchdog;
1075
1076         if (!(new_qdisc->flags & TCQ_F_BUILTIN))
1077                 clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state);
1078
1079         rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
1080         if (need_watchdog_p) {
1081                 dev_queue->trans_start = 0;
1082                 *need_watchdog_p = 1;
1083         }
1084 }
1085
1086 void dev_activate(struct net_device *dev)
1087 {
1088         int need_watchdog;
1089
1090         /* No queueing discipline is attached to device;
1091          * create default one for devices, which need queueing
1092          * and noqueue_qdisc for virtual interfaces
1093          */
1094
1095         if (dev->qdisc == &noop_qdisc)
1096                 attach_default_qdiscs(dev);
1097
1098         if (!netif_carrier_ok(dev))
1099                 /* Delay activation until next carrier-on event */
1100                 return;
1101
1102         need_watchdog = 0;
1103         netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
1104         if (dev_ingress_queue(dev))
1105                 transition_one_qdisc(dev, dev_ingress_queue(dev), NULL);
1106
1107         if (need_watchdog) {
1108                 netif_trans_update(dev);
1109                 dev_watchdog_up(dev);
1110         }
1111 }
1112 EXPORT_SYMBOL(dev_activate);
1113
1114 static void dev_deactivate_queue(struct net_device *dev,
1115                                  struct netdev_queue *dev_queue,
1116                                  void *_qdisc_default)
1117 {
1118         struct Qdisc *qdisc_default = _qdisc_default;
1119         struct Qdisc *qdisc;
1120
1121         qdisc = rtnl_dereference(dev_queue->qdisc);
1122         if (qdisc) {
1123                 bool nolock = qdisc->flags & TCQ_F_NOLOCK;
1124
1125                 if (nolock)
1126                         spin_lock_bh(&qdisc->seqlock);
1127                 spin_lock_bh(qdisc_lock(qdisc));
1128
1129                 if (!(qdisc->flags & TCQ_F_BUILTIN))
1130                         set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
1131
1132                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
1133                 qdisc_reset(qdisc);
1134
1135                 spin_unlock_bh(qdisc_lock(qdisc));
1136                 if (nolock)
1137                         spin_unlock_bh(&qdisc->seqlock);
1138         }
1139 }
1140
1141 static bool some_qdisc_is_busy(struct net_device *dev)
1142 {
1143         unsigned int i;
1144
1145         for (i = 0; i < dev->num_tx_queues; i++) {
1146                 struct netdev_queue *dev_queue;
1147                 spinlock_t *root_lock;
1148                 struct Qdisc *q;
1149                 int val;
1150
1151                 dev_queue = netdev_get_tx_queue(dev, i);
1152                 q = dev_queue->qdisc_sleeping;
1153
1154                 root_lock = qdisc_lock(q);
1155                 spin_lock_bh(root_lock);
1156
1157                 val = (qdisc_is_running(q) ||
1158                        test_bit(__QDISC_STATE_SCHED, &q->state));
1159
1160                 spin_unlock_bh(root_lock);
1161
1162                 if (val)
1163                         return true;
1164         }
1165         return false;
1166 }
1167
1168 static void dev_qdisc_reset(struct net_device *dev,
1169                             struct netdev_queue *dev_queue,
1170                             void *none)
1171 {
1172         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
1173
1174         if (qdisc)
1175                 qdisc_reset(qdisc);
1176 }
1177
1178 /**
1179  *      dev_deactivate_many - deactivate transmissions on several devices
1180  *      @head: list of devices to deactivate
1181  *
1182  *      This function returns only when all outstanding transmissions
1183  *      have completed, unless all devices are in dismantle phase.
1184  */
1185 void dev_deactivate_many(struct list_head *head)
1186 {
1187         struct net_device *dev;
1188
1189         list_for_each_entry(dev, head, close_list) {
1190                 netdev_for_each_tx_queue(dev, dev_deactivate_queue,
1191                                          &noop_qdisc);
1192                 if (dev_ingress_queue(dev))
1193                         dev_deactivate_queue(dev, dev_ingress_queue(dev),
1194                                              &noop_qdisc);
1195
1196                 dev_watchdog_down(dev);
1197         }
1198
1199         /* Wait for outstanding qdisc-less dev_queue_xmit calls.
1200          * This is avoided if all devices are in dismantle phase :
1201          * Caller will call synchronize_net() for us
1202          */
1203         synchronize_net();
1204
1205         /* Wait for outstanding qdisc_run calls. */
1206         list_for_each_entry(dev, head, close_list) {
1207                 while (some_qdisc_is_busy(dev))
1208                         yield();
1209                 /* The new qdisc is assigned at this point so we can safely
1210                  * unwind stale skb lists and qdisc statistics
1211                  */
1212                 netdev_for_each_tx_queue(dev, dev_qdisc_reset, NULL);
1213                 if (dev_ingress_queue(dev))
1214                         dev_qdisc_reset(dev, dev_ingress_queue(dev), NULL);
1215         }
1216 }
1217
1218 void dev_deactivate(struct net_device *dev)
1219 {
1220         LIST_HEAD(single);
1221
1222         list_add(&dev->close_list, &single);
1223         dev_deactivate_many(&single);
1224         list_del(&single);
1225 }
1226 EXPORT_SYMBOL(dev_deactivate);
1227
1228 static int qdisc_change_tx_queue_len(struct net_device *dev,
1229                                      struct netdev_queue *dev_queue)
1230 {
1231         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
1232         const struct Qdisc_ops *ops = qdisc->ops;
1233
1234         if (ops->change_tx_queue_len)
1235                 return ops->change_tx_queue_len(qdisc, dev->tx_queue_len);
1236         return 0;
1237 }
1238
1239 int dev_qdisc_change_tx_queue_len(struct net_device *dev)
1240 {
1241         bool up = dev->flags & IFF_UP;
1242         unsigned int i;
1243         int ret = 0;
1244
1245         if (up)
1246                 dev_deactivate(dev);
1247
1248         for (i = 0; i < dev->num_tx_queues; i++) {
1249                 ret = qdisc_change_tx_queue_len(dev, &dev->_tx[i]);
1250
1251                 /* TODO: revert changes on a partial failure */
1252                 if (ret)
1253                         break;
1254         }
1255
1256         if (up)
1257                 dev_activate(dev);
1258         return ret;
1259 }
1260
1261 static void dev_init_scheduler_queue(struct net_device *dev,
1262                                      struct netdev_queue *dev_queue,
1263                                      void *_qdisc)
1264 {
1265         struct Qdisc *qdisc = _qdisc;
1266
1267         rcu_assign_pointer(dev_queue->qdisc, qdisc);
1268         dev_queue->qdisc_sleeping = qdisc;
1269 }
1270
1271 void dev_init_scheduler(struct net_device *dev)
1272 {
1273         dev->qdisc = &noop_qdisc;
1274         netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
1275         if (dev_ingress_queue(dev))
1276                 dev_init_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
1277
1278         timer_setup(&dev->watchdog_timer, dev_watchdog, 0);
1279 }
1280
1281 static void shutdown_scheduler_queue(struct net_device *dev,
1282                                      struct netdev_queue *dev_queue,
1283                                      void *_qdisc_default)
1284 {
1285         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
1286         struct Qdisc *qdisc_default = _qdisc_default;
1287
1288         if (qdisc) {
1289                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
1290                 dev_queue->qdisc_sleeping = qdisc_default;
1291
1292                 qdisc_put(qdisc);
1293         }
1294 }
1295
1296 void dev_shutdown(struct net_device *dev)
1297 {
1298         netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
1299         if (dev_ingress_queue(dev))
1300                 shutdown_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
1301         qdisc_put(dev->qdisc);
1302         dev->qdisc = &noop_qdisc;
1303
1304         WARN_ON(timer_pending(&dev->watchdog_timer));
1305 }
1306
1307 void psched_ratecfg_precompute(struct psched_ratecfg *r,
1308                                const struct tc_ratespec *conf,
1309                                u64 rate64)
1310 {
1311         memset(r, 0, sizeof(*r));
1312         r->overhead = conf->overhead;
1313         r->rate_bytes_ps = max_t(u64, conf->rate, rate64);
1314         r->linklayer = (conf->linklayer & TC_LINKLAYER_MASK);
1315         r->mult = 1;
1316         /*
1317          * The deal here is to replace a divide by a reciprocal one
1318          * in fast path (a reciprocal divide is a multiply and a shift)
1319          *
1320          * Normal formula would be :
1321          *  time_in_ns = (NSEC_PER_SEC * len) / rate_bps
1322          *
1323          * We compute mult/shift to use instead :
1324          *  time_in_ns = (len * mult) >> shift;
1325          *
1326          * We try to get the highest possible mult value for accuracy,
1327          * but have to make sure no overflows will ever happen.
1328          */
1329         if (r->rate_bytes_ps > 0) {
1330                 u64 factor = NSEC_PER_SEC;
1331
1332                 for (;;) {
1333                         r->mult = div64_u64(factor, r->rate_bytes_ps);
1334                         if (r->mult & (1U << 31) || factor & (1ULL << 63))
1335                                 break;
1336                         factor <<= 1;
1337                         r->shift++;
1338                 }
1339         }
1340 }
1341 EXPORT_SYMBOL(psched_ratecfg_precompute);
1342
1343 static void mini_qdisc_rcu_func(struct rcu_head *head)
1344 {
1345 }
1346
1347 void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp,
1348                           struct tcf_proto *tp_head)
1349 {
1350         /* Protected with chain0->filter_chain_lock.
1351          * Can't access chain directly because tp_head can be NULL.
1352          */
1353         struct mini_Qdisc *miniq_old =
1354                 rcu_dereference_protected(*miniqp->p_miniq, 1);
1355         struct mini_Qdisc *miniq;
1356
1357         if (!tp_head) {
1358                 RCU_INIT_POINTER(*miniqp->p_miniq, NULL);
1359                 /* Wait for flying RCU callback before it is freed. */
1360                 rcu_barrier();
1361                 return;
1362         }
1363
1364         miniq = !miniq_old || miniq_old == &miniqp->miniq2 ?
1365                 &miniqp->miniq1 : &miniqp->miniq2;
1366
1367         /* We need to make sure that readers won't see the miniq
1368          * we are about to modify. So wait until previous call_rcu callback
1369          * is done.
1370          */
1371         rcu_barrier();
1372         miniq->filter_list = tp_head;
1373         rcu_assign_pointer(*miniqp->p_miniq, miniq);
1374
1375         if (miniq_old)
1376                 /* This is counterpart of the rcu barriers above. We need to
1377                  * block potential new user of miniq_old until all readers
1378                  * are not seeing it.
1379                  */
1380                 call_rcu(&miniq_old->rcu, mini_qdisc_rcu_func);
1381 }
1382 EXPORT_SYMBOL(mini_qdisc_pair_swap);
1383
1384 void mini_qdisc_pair_init(struct mini_Qdisc_pair *miniqp, struct Qdisc *qdisc,
1385                           struct mini_Qdisc __rcu **p_miniq)
1386 {
1387         miniqp->miniq1.cpu_bstats = qdisc->cpu_bstats;
1388         miniqp->miniq1.cpu_qstats = qdisc->cpu_qstats;
1389         miniqp->miniq2.cpu_bstats = qdisc->cpu_bstats;
1390         miniqp->miniq2.cpu_qstats = qdisc->cpu_qstats;
1391         miniqp->p_miniq = p_miniq;
1392 }
1393 EXPORT_SYMBOL(mini_qdisc_pair_init);