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