net/sched/sch_generic.c

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