linux/net/sched/sch_generic.c
<<
>>
Prefs
   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 <net/pkt_sched.h>
  29#include <net/dst.h>
  30
  31/* Main transmission queue. */
  32
  33/* Modifications to data participating in scheduling must be protected with
  34 * qdisc_lock(qdisc) spinlock.
  35 *
  36 * The idea is the following:
  37 * - enqueue, dequeue are serialized via qdisc root lock
  38 * - ingress filtering is also serialized via qdisc root lock
  39 * - updates to tree and tree walking are only done under the rtnl mutex.
  40 */
  41
  42static inline int dev_requeue_skb(struct sk_buff *skb, struct Qdisc *q)
  43{
  44        skb_dst_force(skb);
  45        q->gso_skb = skb;
  46        q->qstats.requeues++;
  47        q->q.qlen++;    /* it's still part of the queue */
  48        __netif_schedule(q);
  49
  50        return 0;
  51}
  52
  53static inline struct sk_buff *dequeue_skb(struct Qdisc *q)
  54{
  55        struct sk_buff *skb = q->gso_skb;
  56
  57        if (unlikely(skb)) {
  58                struct net_device *dev = qdisc_dev(q);
  59                struct netdev_queue *txq;
  60
  61                /* check the reason of requeuing without tx lock first */
  62                txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
  63                if (!netif_xmit_frozen_or_stopped(txq)) {
  64                        q->gso_skb = NULL;
  65                        q->q.qlen--;
  66                } else
  67                        skb = NULL;
  68        } else {
  69                skb = q->dequeue(q);
  70        }
  71
  72        return skb;
  73}
  74
  75static inline int handle_dev_cpu_collision(struct sk_buff *skb,
  76                                           struct netdev_queue *dev_queue,
  77                                           struct Qdisc *q)
  78{
  79        int ret;
  80
  81        if (unlikely(dev_queue->xmit_lock_owner == smp_processor_id())) {
  82                /*
  83                 * Same CPU holding the lock. It may be a transient
  84                 * configuration error, when hard_start_xmit() recurses. We
  85                 * detect it by checking xmit owner and drop the packet when
  86                 * deadloop is detected. Return OK to try the next skb.
  87                 */
  88                kfree_skb(skb);
  89                net_warn_ratelimited("Dead loop on netdevice %s, fix it urgently!\n",
  90                                     dev_queue->dev->name);
  91                ret = qdisc_qlen(q);
  92        } else {
  93                /*
  94                 * Another cpu is holding lock, requeue & delay xmits for
  95                 * some time.
  96                 */
  97                __this_cpu_inc(softnet_data.cpu_collision);
  98                ret = dev_requeue_skb(skb, q);
  99        }
 100
 101        return ret;
 102}
 103
 104/*
 105 * Transmit one skb, and handle the return status as required. Holding the
 106 * __QDISC_STATE_RUNNING bit guarantees that only one CPU can execute this
 107 * function.
 108 *
 109 * Returns to the caller:
 110 *                              0  - queue is empty or throttled.
 111 *                              >0 - queue is not empty.
 112 */
 113int sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
 114                    struct net_device *dev, struct netdev_queue *txq,
 115                    spinlock_t *root_lock)
 116{
 117        int ret = NETDEV_TX_BUSY;
 118
 119        /* And release qdisc */
 120        spin_unlock(root_lock);
 121
 122        HARD_TX_LOCK(dev, txq, smp_processor_id());
 123        if (!netif_xmit_frozen_or_stopped(txq))
 124                ret = dev_hard_start_xmit(skb, dev, txq);
 125
 126        HARD_TX_UNLOCK(dev, txq);
 127
 128        spin_lock(root_lock);
 129
 130        if (dev_xmit_complete(ret)) {
 131                /* Driver sent out skb successfully or skb was consumed */
 132                ret = qdisc_qlen(q);
 133        } else if (ret == NETDEV_TX_LOCKED) {
 134                /* Driver try lock failed */
 135                ret = handle_dev_cpu_collision(skb, txq, q);
 136        } else {
 137                /* Driver returned NETDEV_TX_BUSY - requeue skb */
 138                if (unlikely(ret != NETDEV_TX_BUSY))
 139                        net_warn_ratelimited("BUG %s code %d qlen %d\n",
 140                                             dev->name, ret, q->q.qlen);
 141
 142                ret = dev_requeue_skb(skb, q);
 143        }
 144
 145        if (ret && netif_xmit_frozen_or_stopped(txq))
 146                ret = 0;
 147
 148        return ret;
 149}
 150
 151/*
 152 * NOTE: Called under qdisc_lock(q) with locally disabled BH.
 153 *
 154 * __QDISC_STATE_RUNNING guarantees only one CPU can process
 155 * this qdisc at a time. qdisc_lock(q) serializes queue accesses for
 156 * this queue.
 157 *
 158 *  netif_tx_lock serializes accesses to device driver.
 159 *
 160 *  qdisc_lock(q) and netif_tx_lock are mutually exclusive,
 161 *  if one is grabbed, another must be free.
 162 *
 163 * Note, that this procedure can be called by a watchdog timer
 164 *
 165 * Returns to the caller:
 166 *                              0  - queue is empty or throttled.
 167 *                              >0 - queue is not empty.
 168 *
 169 */
 170static inline int qdisc_restart(struct Qdisc *q)
 171{
 172        struct netdev_queue *txq;
 173        struct net_device *dev;
 174        spinlock_t *root_lock;
 175        struct sk_buff *skb;
 176
 177        /* Dequeue packet */
 178        skb = dequeue_skb(q);
 179        if (unlikely(!skb))
 180                return 0;
 181        WARN_ON_ONCE(skb_dst_is_noref(skb));
 182        root_lock = qdisc_lock(q);
 183        dev = qdisc_dev(q);
 184        txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
 185
 186        return sch_direct_xmit(skb, q, dev, txq, root_lock);
 187}
 188
 189void __qdisc_run(struct Qdisc *q)
 190{
 191        int quota = weight_p;
 192
 193        while (qdisc_restart(q)) {
 194                /*
 195                 * Ordered by possible occurrence: Postpone processing if
 196                 * 1. we've exceeded packet quota
 197                 * 2. another process needs the CPU;
 198                 */
 199                if (--quota <= 0 || need_resched()) {
 200                        __netif_schedule(q);
 201                        break;
 202                }
 203        }
 204
 205        qdisc_run_end(q);
 206}
 207
 208unsigned long dev_trans_start(struct net_device *dev)
 209{
 210        unsigned long val, res = dev->trans_start;
 211        unsigned int i;
 212
 213        for (i = 0; i < dev->num_tx_queues; i++) {
 214                val = netdev_get_tx_queue(dev, i)->trans_start;
 215                if (val && time_after(val, res))
 216                        res = val;
 217        }
 218        dev->trans_start = res;
 219        return res;
 220}
 221EXPORT_SYMBOL(dev_trans_start);
 222
 223static void dev_watchdog(unsigned long arg)
 224{
 225        struct net_device *dev = (struct net_device *)arg;
 226
 227        netif_tx_lock(dev);
 228        if (!qdisc_tx_is_noop(dev)) {
 229                if (netif_device_present(dev) &&
 230                    netif_running(dev) &&
 231                    netif_carrier_ok(dev)) {
 232                        int some_queue_timedout = 0;
 233                        unsigned int i;
 234                        unsigned long trans_start;
 235
 236                        for (i = 0; i < dev->num_tx_queues; i++) {
 237                                struct netdev_queue *txq;
 238
 239                                txq = netdev_get_tx_queue(dev, i);
 240                                /*
 241                                 * old device drivers set dev->trans_start
 242                                 */
 243                                trans_start = txq->trans_start ? : dev->trans_start;
 244                                if (netif_xmit_stopped(txq) &&
 245                                    time_after(jiffies, (trans_start +
 246                                                         dev->watchdog_timeo))) {
 247                                        some_queue_timedout = 1;
 248                                        txq->trans_timeout++;
 249                                        break;
 250                                }
 251                        }
 252
 253                        if (some_queue_timedout) {
 254                                WARN_ONCE(1, KERN_INFO "NETDEV WATCHDOG: %s (%s): transmit queue %u timed out\n",
 255                                       dev->name, netdev_drivername(dev), i);
 256                                dev->netdev_ops->ndo_tx_timeout(dev);
 257                        }
 258                        if (!mod_timer(&dev->watchdog_timer,
 259                                       round_jiffies(jiffies +
 260                                                     dev->watchdog_timeo)))
 261                                dev_hold(dev);
 262                }
 263        }
 264        netif_tx_unlock(dev);
 265
 266        dev_put(dev);
 267}
 268
 269void __netdev_watchdog_up(struct net_device *dev)
 270{
 271        if (dev->netdev_ops->ndo_tx_timeout) {
 272                if (dev->watchdog_timeo <= 0)
 273                        dev->watchdog_timeo = 5*HZ;
 274                if (!mod_timer(&dev->watchdog_timer,
 275                               round_jiffies(jiffies + dev->watchdog_timeo)))
 276                        dev_hold(dev);
 277        }
 278}
 279
 280static void dev_watchdog_up(struct net_device *dev)
 281{
 282        __netdev_watchdog_up(dev);
 283}
 284
 285static void dev_watchdog_down(struct net_device *dev)
 286{
 287        netif_tx_lock_bh(dev);
 288        if (del_timer(&dev->watchdog_timer))
 289                dev_put(dev);
 290        netif_tx_unlock_bh(dev);
 291}
 292
 293/**
 294 *      netif_carrier_on - set carrier
 295 *      @dev: network device
 296 *
 297 * Device has detected that carrier.
 298 */
 299void netif_carrier_on(struct net_device *dev)
 300{
 301        if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
 302                if (dev->reg_state == NETREG_UNINITIALIZED)
 303                        return;
 304                linkwatch_fire_event(dev);
 305                if (netif_running(dev))
 306                        __netdev_watchdog_up(dev);
 307        }
 308}
 309EXPORT_SYMBOL(netif_carrier_on);
 310
 311/**
 312 *      netif_carrier_off - clear carrier
 313 *      @dev: network device
 314 *
 315 * Device has detected loss of carrier.
 316 */
 317void netif_carrier_off(struct net_device *dev)
 318{
 319        if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
 320                if (dev->reg_state == NETREG_UNINITIALIZED)
 321                        return;
 322                linkwatch_fire_event(dev);
 323        }
 324}
 325EXPORT_SYMBOL(netif_carrier_off);
 326
 327/**
 328 *      netif_notify_peers - notify network peers about existence of @dev
 329 *      @dev: network device
 330 *
 331 * Generate traffic such that interested network peers are aware of
 332 * @dev, such as by generating a gratuitous ARP. This may be used when
 333 * a device wants to inform the rest of the network about some sort of
 334 * reconfiguration such as a failover event or virtual machine
 335 * migration.
 336 */
 337void netif_notify_peers(struct net_device *dev)
 338{
 339        rtnl_lock();
 340        call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, dev);
 341        rtnl_unlock();
 342}
 343EXPORT_SYMBOL(netif_notify_peers);
 344
 345/* "NOOP" scheduler: the best scheduler, recommended for all interfaces
 346   under all circumstances. It is difficult to invent anything faster or
 347   cheaper.
 348 */
 349
 350static int noop_enqueue(struct sk_buff *skb, struct Qdisc * qdisc)
 351{
 352        kfree_skb(skb);
 353        return NET_XMIT_CN;
 354}
 355
 356static struct sk_buff *noop_dequeue(struct Qdisc * qdisc)
 357{
 358        return NULL;
 359}
 360
 361struct Qdisc_ops noop_qdisc_ops __read_mostly = {
 362        .id             =       "noop",
 363        .priv_size      =       0,
 364        .enqueue        =       noop_enqueue,
 365        .dequeue        =       noop_dequeue,
 366        .peek           =       noop_dequeue,
 367        .owner          =       THIS_MODULE,
 368};
 369
 370static struct netdev_queue noop_netdev_queue = {
 371        .qdisc          =       &noop_qdisc,
 372        .qdisc_sleeping =       &noop_qdisc,
 373};
 374
 375struct Qdisc noop_qdisc = {
 376        .enqueue        =       noop_enqueue,
 377        .dequeue        =       noop_dequeue,
 378        .flags          =       TCQ_F_BUILTIN,
 379        .ops            =       &noop_qdisc_ops,
 380        .list           =       LIST_HEAD_INIT(noop_qdisc.list),
 381        .q.lock         =       __SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
 382        .dev_queue      =       &noop_netdev_queue,
 383        .busylock       =       __SPIN_LOCK_UNLOCKED(noop_qdisc.busylock),
 384};
 385EXPORT_SYMBOL(noop_qdisc);
 386
 387static struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
 388        .id             =       "noqueue",
 389        .priv_size      =       0,
 390        .enqueue        =       noop_enqueue,
 391        .dequeue        =       noop_dequeue,
 392        .peek           =       noop_dequeue,
 393        .owner          =       THIS_MODULE,
 394};
 395
 396static struct Qdisc noqueue_qdisc;
 397static struct netdev_queue noqueue_netdev_queue = {
 398        .qdisc          =       &noqueue_qdisc,
 399        .qdisc_sleeping =       &noqueue_qdisc,
 400};
 401
 402static struct Qdisc noqueue_qdisc = {
 403        .enqueue        =       NULL,
 404        .dequeue        =       noop_dequeue,
 405        .flags          =       TCQ_F_BUILTIN,
 406        .ops            =       &noqueue_qdisc_ops,
 407        .list           =       LIST_HEAD_INIT(noqueue_qdisc.list),
 408        .q.lock         =       __SPIN_LOCK_UNLOCKED(noqueue_qdisc.q.lock),
 409        .dev_queue      =       &noqueue_netdev_queue,
 410        .busylock       =       __SPIN_LOCK_UNLOCKED(noqueue_qdisc.busylock),
 411};
 412
 413
 414static const u8 prio2band[TC_PRIO_MAX + 1] = {
 415        1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1
 416};
 417
 418/* 3-band FIFO queue: old style, but should be a bit faster than
 419   generic prio+fifo combination.
 420 */
 421
 422#define PFIFO_FAST_BANDS 3
 423
 424/*
 425 * Private data for a pfifo_fast scheduler containing:
 426 *      - queues for the three band
 427 *      - bitmap indicating which of the bands contain skbs
 428 */
 429struct pfifo_fast_priv {
 430        u32 bitmap;
 431        struct sk_buff_head q[PFIFO_FAST_BANDS];
 432};
 433
 434/*
 435 * Convert a bitmap to the first band number where an skb is queued, where:
 436 *      bitmap=0 means there are no skbs on any band.
 437 *      bitmap=1 means there is an skb on band 0.
 438 *      bitmap=7 means there are skbs on all 3 bands, etc.
 439 */
 440static const int bitmap2band[] = {-1, 0, 1, 0, 2, 0, 1, 0};
 441
 442static inline struct sk_buff_head *band2list(struct pfifo_fast_priv *priv,
 443                                             int band)
 444{
 445        return priv->q + band;
 446}
 447
 448static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc)
 449{
 450        if (skb_queue_len(&qdisc->q) < qdisc_dev(qdisc)->tx_queue_len) {
 451                int band = prio2band[skb->priority & TC_PRIO_MAX];
 452                struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 453                struct sk_buff_head *list = band2list(priv, band);
 454
 455                priv->bitmap |= (1 << band);
 456                qdisc->q.qlen++;
 457                return __qdisc_enqueue_tail(skb, qdisc, list);
 458        }
 459
 460        return qdisc_drop(skb, qdisc);
 461}
 462
 463static struct sk_buff *pfifo_fast_dequeue(struct Qdisc *qdisc)
 464{
 465        struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 466        int band = bitmap2band[priv->bitmap];
 467
 468        if (likely(band >= 0)) {
 469                struct sk_buff_head *list = band2list(priv, band);
 470                struct sk_buff *skb = __qdisc_dequeue_head(qdisc, list);
 471
 472                qdisc->q.qlen--;
 473                if (skb_queue_empty(list))
 474                        priv->bitmap &= ~(1 << band);
 475
 476                return skb;
 477        }
 478
 479        return NULL;
 480}
 481
 482static struct sk_buff *pfifo_fast_peek(struct Qdisc *qdisc)
 483{
 484        struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 485        int band = bitmap2band[priv->bitmap];
 486
 487        if (band >= 0) {
 488                struct sk_buff_head *list = band2list(priv, band);
 489
 490                return skb_peek(list);
 491        }
 492
 493        return NULL;
 494}
 495
 496static void pfifo_fast_reset(struct Qdisc *qdisc)
 497{
 498        int prio;
 499        struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 500
 501        for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
 502                __qdisc_reset_queue(qdisc, band2list(priv, prio));
 503
 504        priv->bitmap = 0;
 505        qdisc->qstats.backlog = 0;
 506        qdisc->q.qlen = 0;
 507}
 508
 509static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
 510{
 511        struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
 512
 513        memcpy(&opt.priomap, prio2band, TC_PRIO_MAX + 1);
 514        if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
 515                goto nla_put_failure;
 516        return skb->len;
 517
 518nla_put_failure:
 519        return -1;
 520}
 521
 522static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt)
 523{
 524        int prio;
 525        struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 526
 527        for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
 528                skb_queue_head_init(band2list(priv, prio));
 529
 530        /* Can by-pass the queue discipline */
 531        qdisc->flags |= TCQ_F_CAN_BYPASS;
 532        return 0;
 533}
 534
 535struct Qdisc_ops pfifo_fast_ops __read_mostly = {
 536        .id             =       "pfifo_fast",
 537        .priv_size      =       sizeof(struct pfifo_fast_priv),
 538        .enqueue        =       pfifo_fast_enqueue,
 539        .dequeue        =       pfifo_fast_dequeue,
 540        .peek           =       pfifo_fast_peek,
 541        .init           =       pfifo_fast_init,
 542        .reset          =       pfifo_fast_reset,
 543        .dump           =       pfifo_fast_dump,
 544        .owner          =       THIS_MODULE,
 545};
 546EXPORT_SYMBOL(pfifo_fast_ops);
 547
 548struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
 549                          struct Qdisc_ops *ops)
 550{
 551        void *p;
 552        struct Qdisc *sch;
 553        unsigned int size = QDISC_ALIGN(sizeof(*sch)) + ops->priv_size;
 554        int err = -ENOBUFS;
 555
 556        p = kzalloc_node(size, GFP_KERNEL,
 557                         netdev_queue_numa_node_read(dev_queue));
 558
 559        if (!p)
 560                goto errout;
 561        sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
 562        /* if we got non aligned memory, ask more and do alignment ourself */
 563        if (sch != p) {
 564                kfree(p);
 565                p = kzalloc_node(size + QDISC_ALIGNTO - 1, GFP_KERNEL,
 566                                 netdev_queue_numa_node_read(dev_queue));
 567                if (!p)
 568                        goto errout;
 569                sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
 570                sch->padded = (char *) sch - (char *) p;
 571        }
 572        INIT_LIST_HEAD(&sch->list);
 573        skb_queue_head_init(&sch->q);
 574        spin_lock_init(&sch->busylock);
 575        sch->ops = ops;
 576        sch->enqueue = ops->enqueue;
 577        sch->dequeue = ops->dequeue;
 578        sch->dev_queue = dev_queue;
 579        dev_hold(qdisc_dev(sch));
 580        atomic_set(&sch->refcnt, 1);
 581
 582        return sch;
 583errout:
 584        return ERR_PTR(err);
 585}
 586
 587struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
 588                                struct Qdisc_ops *ops, unsigned int parentid)
 589{
 590        struct Qdisc *sch;
 591
 592        sch = qdisc_alloc(dev_queue, ops);
 593        if (IS_ERR(sch))
 594                goto errout;
 595        sch->parent = parentid;
 596
 597        if (!ops->init || ops->init(sch, NULL) == 0)
 598                return sch;
 599
 600        qdisc_destroy(sch);
 601errout:
 602        return NULL;
 603}
 604EXPORT_SYMBOL(qdisc_create_dflt);
 605
 606/* Under qdisc_lock(qdisc) and BH! */
 607
 608void qdisc_reset(struct Qdisc *qdisc)
 609{
 610        const struct Qdisc_ops *ops = qdisc->ops;
 611
 612        if (ops->reset)
 613                ops->reset(qdisc);
 614
 615        if (qdisc->gso_skb) {
 616                kfree_skb(qdisc->gso_skb);
 617                qdisc->gso_skb = NULL;
 618                qdisc->q.qlen = 0;
 619        }
 620}
 621EXPORT_SYMBOL(qdisc_reset);
 622
 623static void qdisc_rcu_free(struct rcu_head *head)
 624{
 625        struct Qdisc *qdisc = container_of(head, struct Qdisc, rcu_head);
 626
 627        kfree((char *) qdisc - qdisc->padded);
 628}
 629
 630void qdisc_destroy(struct Qdisc *qdisc)
 631{
 632        const struct Qdisc_ops  *ops = qdisc->ops;
 633
 634        if (qdisc->flags & TCQ_F_BUILTIN ||
 635            !atomic_dec_and_test(&qdisc->refcnt))
 636                return;
 637
 638#ifdef CONFIG_NET_SCHED
 639        qdisc_list_del(qdisc);
 640
 641        qdisc_put_stab(rtnl_dereference(qdisc->stab));
 642#endif
 643        gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est);
 644        if (ops->reset)
 645                ops->reset(qdisc);
 646        if (ops->destroy)
 647                ops->destroy(qdisc);
 648
 649        module_put(ops->owner);
 650        dev_put(qdisc_dev(qdisc));
 651
 652        kfree_skb(qdisc->gso_skb);
 653        /*
 654         * gen_estimator est_timer() might access qdisc->q.lock,
 655         * wait a RCU grace period before freeing qdisc.
 656         */
 657        call_rcu(&qdisc->rcu_head, qdisc_rcu_free);
 658}
 659EXPORT_SYMBOL(qdisc_destroy);
 660
 661/* Attach toplevel qdisc to device queue. */
 662struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
 663                              struct Qdisc *qdisc)
 664{
 665        struct Qdisc *oqdisc = dev_queue->qdisc_sleeping;
 666        spinlock_t *root_lock;
 667
 668        root_lock = qdisc_lock(oqdisc);
 669        spin_lock_bh(root_lock);
 670
 671        /* Prune old scheduler */
 672        if (oqdisc && atomic_read(&oqdisc->refcnt) <= 1)
 673                qdisc_reset(oqdisc);
 674
 675        /* ... and graft new one */
 676        if (qdisc == NULL)
 677                qdisc = &noop_qdisc;
 678        dev_queue->qdisc_sleeping = qdisc;
 679        rcu_assign_pointer(dev_queue->qdisc, &noop_qdisc);
 680
 681        spin_unlock_bh(root_lock);
 682
 683        return oqdisc;
 684}
 685EXPORT_SYMBOL(dev_graft_qdisc);
 686
 687static void attach_one_default_qdisc(struct net_device *dev,
 688                                     struct netdev_queue *dev_queue,
 689                                     void *_unused)
 690{
 691        struct Qdisc *qdisc = &noqueue_qdisc;
 692
 693        if (dev->tx_queue_len) {
 694                qdisc = qdisc_create_dflt(dev_queue,
 695                                          &pfifo_fast_ops, TC_H_ROOT);
 696                if (!qdisc) {
 697                        netdev_info(dev, "activation failed\n");
 698                        return;
 699                }
 700        }
 701        dev_queue->qdisc_sleeping = qdisc;
 702}
 703
 704static void attach_default_qdiscs(struct net_device *dev)
 705{
 706        struct netdev_queue *txq;
 707        struct Qdisc *qdisc;
 708
 709        txq = netdev_get_tx_queue(dev, 0);
 710
 711        if (!netif_is_multiqueue(dev) || dev->tx_queue_len == 0) {
 712                netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
 713                dev->qdisc = txq->qdisc_sleeping;
 714                atomic_inc(&dev->qdisc->refcnt);
 715        } else {
 716                qdisc = qdisc_create_dflt(txq, &mq_qdisc_ops, TC_H_ROOT);
 717                if (qdisc) {
 718                        qdisc->ops->attach(qdisc);
 719                        dev->qdisc = qdisc;
 720                }
 721        }
 722}
 723
 724static void transition_one_qdisc(struct net_device *dev,
 725                                 struct netdev_queue *dev_queue,
 726                                 void *_need_watchdog)
 727{
 728        struct Qdisc *new_qdisc = dev_queue->qdisc_sleeping;
 729        int *need_watchdog_p = _need_watchdog;
 730
 731        if (!(new_qdisc->flags & TCQ_F_BUILTIN))
 732                clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state);
 733
 734        rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
 735        if (need_watchdog_p && new_qdisc != &noqueue_qdisc) {
 736                dev_queue->trans_start = 0;
 737                *need_watchdog_p = 1;
 738        }
 739}
 740
 741void dev_activate(struct net_device *dev)
 742{
 743        int need_watchdog;
 744
 745        /* No queueing discipline is attached to device;
 746           create default one i.e. pfifo_fast for devices,
 747           which need queueing and noqueue_qdisc for
 748           virtual interfaces
 749         */
 750
 751        if (dev->qdisc == &noop_qdisc)
 752                attach_default_qdiscs(dev);
 753
 754        if (!netif_carrier_ok(dev))
 755                /* Delay activation until next carrier-on event */
 756                return;
 757
 758        need_watchdog = 0;
 759        netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
 760        if (dev_ingress_queue(dev))
 761                transition_one_qdisc(dev, dev_ingress_queue(dev), NULL);
 762
 763        if (need_watchdog) {
 764                dev->trans_start = jiffies;
 765                dev_watchdog_up(dev);
 766        }
 767}
 768EXPORT_SYMBOL(dev_activate);
 769
 770static void dev_deactivate_queue(struct net_device *dev,
 771                                 struct netdev_queue *dev_queue,
 772                                 void *_qdisc_default)
 773{
 774        struct Qdisc *qdisc_default = _qdisc_default;
 775        struct Qdisc *qdisc;
 776
 777        qdisc = dev_queue->qdisc;
 778        if (qdisc) {
 779                spin_lock_bh(qdisc_lock(qdisc));
 780
 781                if (!(qdisc->flags & TCQ_F_BUILTIN))
 782                        set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
 783
 784                rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
 785                qdisc_reset(qdisc);
 786
 787                spin_unlock_bh(qdisc_lock(qdisc));
 788        }
 789}
 790
 791static bool some_qdisc_is_busy(struct net_device *dev)
 792{
 793        unsigned int i;
 794
 795        for (i = 0; i < dev->num_tx_queues; i++) {
 796                struct netdev_queue *dev_queue;
 797                spinlock_t *root_lock;
 798                struct Qdisc *q;
 799                int val;
 800
 801                dev_queue = netdev_get_tx_queue(dev, i);
 802                q = dev_queue->qdisc_sleeping;
 803                root_lock = qdisc_lock(q);
 804
 805                spin_lock_bh(root_lock);
 806
 807                val = (qdisc_is_running(q) ||
 808                       test_bit(__QDISC_STATE_SCHED, &q->state));
 809
 810                spin_unlock_bh(root_lock);
 811
 812                if (val)
 813                        return true;
 814        }
 815        return false;
 816}
 817
 818/**
 819 *      dev_deactivate_many - deactivate transmissions on several devices
 820 *      @head: list of devices to deactivate
 821 *
 822 *      This function returns only when all outstanding transmissions
 823 *      have completed, unless all devices are in dismantle phase.
 824 */
 825void dev_deactivate_many(struct list_head *head)
 826{
 827        struct net_device *dev;
 828        bool sync_needed = false;
 829
 830        list_for_each_entry(dev, head, unreg_list) {
 831                netdev_for_each_tx_queue(dev, dev_deactivate_queue,
 832                                         &noop_qdisc);
 833                if (dev_ingress_queue(dev))
 834                        dev_deactivate_queue(dev, dev_ingress_queue(dev),
 835                                             &noop_qdisc);
 836
 837                dev_watchdog_down(dev);
 838                sync_needed |= !dev->dismantle;
 839        }
 840
 841        /* Wait for outstanding qdisc-less dev_queue_xmit calls.
 842         * This is avoided if all devices are in dismantle phase :
 843         * Caller will call synchronize_net() for us
 844         */
 845        if (sync_needed)
 846                synchronize_net();
 847
 848        /* Wait for outstanding qdisc_run calls. */
 849        list_for_each_entry(dev, head, unreg_list)
 850                while (some_qdisc_is_busy(dev))
 851                        yield();
 852}
 853
 854void dev_deactivate(struct net_device *dev)
 855{
 856        LIST_HEAD(single);
 857
 858        list_add(&dev->unreg_list, &single);
 859        dev_deactivate_many(&single);
 860        list_del(&single);
 861}
 862EXPORT_SYMBOL(dev_deactivate);
 863
 864static void dev_init_scheduler_queue(struct net_device *dev,
 865                                     struct netdev_queue *dev_queue,
 866                                     void *_qdisc)
 867{
 868        struct Qdisc *qdisc = _qdisc;
 869
 870        dev_queue->qdisc = qdisc;
 871        dev_queue->qdisc_sleeping = qdisc;
 872}
 873
 874void dev_init_scheduler(struct net_device *dev)
 875{
 876        dev->qdisc = &noop_qdisc;
 877        netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
 878        if (dev_ingress_queue(dev))
 879                dev_init_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
 880
 881        setup_timer(&dev->watchdog_timer, dev_watchdog, (unsigned long)dev);
 882}
 883
 884static void shutdown_scheduler_queue(struct net_device *dev,
 885                                     struct netdev_queue *dev_queue,
 886                                     void *_qdisc_default)
 887{
 888        struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
 889        struct Qdisc *qdisc_default = _qdisc_default;
 890
 891        if (qdisc) {
 892                rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
 893                dev_queue->qdisc_sleeping = qdisc_default;
 894
 895                qdisc_destroy(qdisc);
 896        }
 897}
 898
 899void dev_shutdown(struct net_device *dev)
 900{
 901        netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
 902        if (dev_ingress_queue(dev))
 903                shutdown_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
 904        qdisc_destroy(dev->qdisc);
 905        dev->qdisc = &noop_qdisc;
 906
 907        WARN_ON(timer_pending(&dev->watchdog_timer));
 908}
 909
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.