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[mirror_ubuntu-jammy-kernel.git] / net / sched / sch_generic.c
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * net/sched/sch_generic.c Generic packet scheduler routines.
4 *
5 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
6 * Jamal Hadi Salim, <hadi@cyberus.ca> 990601
7 * - Ingress support
8 */
9
10 #include <linux/bitops.h>
11 #include <linux/module.h>
12 #include <linux/types.h>
13 #include <linux/kernel.h>
14 #include <linux/sched.h>
15 #include <linux/string.h>
16 #include <linux/errno.h>
17 #include <linux/netdevice.h>
18 #include <linux/skbuff.h>
19 #include <linux/rtnetlink.h>
20 #include <linux/init.h>
21 #include <linux/rcupdate.h>
22 #include <linux/list.h>
23 #include <linux/slab.h>
24 #include <linux/if_vlan.h>
25 #include <linux/skb_array.h>
26 #include <linux/if_macvlan.h>
27 #include <net/sch_generic.h>
28 #include <net/pkt_sched.h>
29 #include <net/dst.h>
30 #include <trace/events/qdisc.h>
31 #include <trace/events/net.h>
32 #include <net/xfrm.h>
33
34 /* Qdisc to use by default */
35 const struct Qdisc_ops *default_qdisc_ops = &pfifo_fast_ops;
36 EXPORT_SYMBOL(default_qdisc_ops);
37
38 static void qdisc_maybe_clear_missed(struct Qdisc *q,
39 const struct netdev_queue *txq)
40 {
41 clear_bit(__QDISC_STATE_MISSED, &q->state);
42
43 /* Make sure the below netif_xmit_frozen_or_stopped()
44 * checking happens after clearing STATE_MISSED.
45 */
46 smp_mb__after_atomic();
47
48 /* Checking netif_xmit_frozen_or_stopped() again to
49 * make sure STATE_MISSED is set if the STATE_MISSED
50 * set by netif_tx_wake_queue()'s rescheduling of
51 * net_tx_action() is cleared by the above clear_bit().
52 */
53 if (!netif_xmit_frozen_or_stopped(txq))
54 set_bit(__QDISC_STATE_MISSED, &q->state);
55 else
56 set_bit(__QDISC_STATE_DRAINING, &q->state);
57 }
58
59 /* Main transmission queue. */
60
61 /* Modifications to data participating in scheduling must be protected with
62 * qdisc_lock(qdisc) spinlock.
63 *
64 * The idea is the following:
65 * - enqueue, dequeue are serialized via qdisc root lock
66 * - ingress filtering is also serialized via qdisc root lock
67 * - updates to tree and tree walking are only done under the rtnl mutex.
68 */
69
70 #define SKB_XOFF_MAGIC ((struct sk_buff *)1UL)
71
72 static inline struct sk_buff *__skb_dequeue_bad_txq(struct Qdisc *q)
73 {
74 const struct netdev_queue *txq = q->dev_queue;
75 spinlock_t *lock = NULL;
76 struct sk_buff *skb;
77
78 if (q->flags & TCQ_F_NOLOCK) {
79 lock = qdisc_lock(q);
80 spin_lock(lock);
81 }
82
83 skb = skb_peek(&q->skb_bad_txq);
84 if (skb) {
85 /* check the reason of requeuing without tx lock first */
86 txq = skb_get_tx_queue(txq->dev, skb);
87 if (!netif_xmit_frozen_or_stopped(txq)) {
88 skb = __skb_dequeue(&q->skb_bad_txq);
89 if (qdisc_is_percpu_stats(q)) {
90 qdisc_qstats_cpu_backlog_dec(q, skb);
91 qdisc_qstats_cpu_qlen_dec(q);
92 } else {
93 qdisc_qstats_backlog_dec(q, skb);
94 q->q.qlen--;
95 }
96 } else {
97 skb = SKB_XOFF_MAGIC;
98 qdisc_maybe_clear_missed(q, txq);
99 }
100 }
101
102 if (lock)
103 spin_unlock(lock);
104
105 return skb;
106 }
107
108 static inline struct sk_buff *qdisc_dequeue_skb_bad_txq(struct Qdisc *q)
109 {
110 struct sk_buff *skb = skb_peek(&q->skb_bad_txq);
111
112 if (unlikely(skb))
113 skb = __skb_dequeue_bad_txq(q);
114
115 return skb;
116 }
117
118 static inline void qdisc_enqueue_skb_bad_txq(struct Qdisc *q,
119 struct sk_buff *skb)
120 {
121 spinlock_t *lock = NULL;
122
123 if (q->flags & TCQ_F_NOLOCK) {
124 lock = qdisc_lock(q);
125 spin_lock(lock);
126 }
127
128 __skb_queue_tail(&q->skb_bad_txq, skb);
129
130 if (qdisc_is_percpu_stats(q)) {
131 qdisc_qstats_cpu_backlog_inc(q, skb);
132 qdisc_qstats_cpu_qlen_inc(q);
133 } else {
134 qdisc_qstats_backlog_inc(q, skb);
135 q->q.qlen++;
136 }
137
138 if (lock)
139 spin_unlock(lock);
140 }
141
142 static inline void dev_requeue_skb(struct sk_buff *skb, struct Qdisc *q)
143 {
144 spinlock_t *lock = NULL;
145
146 if (q->flags & TCQ_F_NOLOCK) {
147 lock = qdisc_lock(q);
148 spin_lock(lock);
149 }
150
151 while (skb) {
152 struct sk_buff *next = skb->next;
153
154 __skb_queue_tail(&q->gso_skb, skb);
155
156 /* it's still part of the queue */
157 if (qdisc_is_percpu_stats(q)) {
158 qdisc_qstats_cpu_requeues_inc(q);
159 qdisc_qstats_cpu_backlog_inc(q, skb);
160 qdisc_qstats_cpu_qlen_inc(q);
161 } else {
162 q->qstats.requeues++;
163 qdisc_qstats_backlog_inc(q, skb);
164 q->q.qlen++;
165 }
166
167 skb = next;
168 }
169
170 if (lock) {
171 spin_unlock(lock);
172 set_bit(__QDISC_STATE_MISSED, &q->state);
173 } else {
174 __netif_schedule(q);
175 }
176 }
177
178 static void try_bulk_dequeue_skb(struct Qdisc *q,
179 struct sk_buff *skb,
180 const struct netdev_queue *txq,
181 int *packets)
182 {
183 int bytelimit = qdisc_avail_bulklimit(txq) - skb->len;
184
185 while (bytelimit > 0) {
186 struct sk_buff *nskb = q->dequeue(q);
187
188 if (!nskb)
189 break;
190
191 bytelimit -= nskb->len; /* covers GSO len */
192 skb->next = nskb;
193 skb = nskb;
194 (*packets)++; /* GSO counts as one pkt */
195 }
196 skb_mark_not_on_list(skb);
197 }
198
199 /* This variant of try_bulk_dequeue_skb() makes sure
200 * all skbs in the chain are for the same txq
201 */
202 static void try_bulk_dequeue_skb_slow(struct Qdisc *q,
203 struct sk_buff *skb,
204 int *packets)
205 {
206 int mapping = skb_get_queue_mapping(skb);
207 struct sk_buff *nskb;
208 int cnt = 0;
209
210 do {
211 nskb = q->dequeue(q);
212 if (!nskb)
213 break;
214 if (unlikely(skb_get_queue_mapping(nskb) != mapping)) {
215 qdisc_enqueue_skb_bad_txq(q, nskb);
216 break;
217 }
218 skb->next = nskb;
219 skb = nskb;
220 } while (++cnt < 8);
221 (*packets) += cnt;
222 skb_mark_not_on_list(skb);
223 }
224
225 /* Note that dequeue_skb can possibly return a SKB list (via skb->next).
226 * A requeued skb (via q->gso_skb) can also be a SKB list.
227 */
228 static struct sk_buff *dequeue_skb(struct Qdisc *q, bool *validate,
229 int *packets)
230 {
231 const struct netdev_queue *txq = q->dev_queue;
232 struct sk_buff *skb = NULL;
233
234 *packets = 1;
235 if (unlikely(!skb_queue_empty(&q->gso_skb))) {
236 spinlock_t *lock = NULL;
237
238 if (q->flags & TCQ_F_NOLOCK) {
239 lock = qdisc_lock(q);
240 spin_lock(lock);
241 }
242
243 skb = skb_peek(&q->gso_skb);
244
245 /* skb may be null if another cpu pulls gso_skb off in between
246 * empty check and lock.
247 */
248 if (!skb) {
249 if (lock)
250 spin_unlock(lock);
251 goto validate;
252 }
253
254 /* skb in gso_skb were already validated */
255 *validate = false;
256 if (xfrm_offload(skb))
257 *validate = true;
258 /* check the reason of requeuing without tx lock first */
259 txq = skb_get_tx_queue(txq->dev, skb);
260 if (!netif_xmit_frozen_or_stopped(txq)) {
261 skb = __skb_dequeue(&q->gso_skb);
262 if (qdisc_is_percpu_stats(q)) {
263 qdisc_qstats_cpu_backlog_dec(q, skb);
264 qdisc_qstats_cpu_qlen_dec(q);
265 } else {
266 qdisc_qstats_backlog_dec(q, skb);
267 q->q.qlen--;
268 }
269 } else {
270 skb = NULL;
271 qdisc_maybe_clear_missed(q, txq);
272 }
273 if (lock)
274 spin_unlock(lock);
275 goto trace;
276 }
277 validate:
278 *validate = true;
279
280 if ((q->flags & TCQ_F_ONETXQUEUE) &&
281 netif_xmit_frozen_or_stopped(txq)) {
282 qdisc_maybe_clear_missed(q, txq);
283 return skb;
284 }
285
286 skb = qdisc_dequeue_skb_bad_txq(q);
287 if (unlikely(skb)) {
288 if (skb == SKB_XOFF_MAGIC)
289 return NULL;
290 goto bulk;
291 }
292 skb = q->dequeue(q);
293 if (skb) {
294 bulk:
295 if (qdisc_may_bulk(q))
296 try_bulk_dequeue_skb(q, skb, txq, packets);
297 else
298 try_bulk_dequeue_skb_slow(q, skb, packets);
299 }
300 trace:
301 trace_qdisc_dequeue(q, txq, *packets, skb);
302 return skb;
303 }
304
305 /*
306 * Transmit possibly several skbs, and handle the return status as
307 * required. Owning running seqcount bit guarantees that
308 * only one CPU can execute this function.
309 *
310 * Returns to the caller:
311 * false - hardware queue frozen backoff
312 * true - feel free to send more pkts
313 */
314 bool sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
315 struct net_device *dev, struct netdev_queue *txq,
316 spinlock_t *root_lock, bool validate)
317 {
318 int ret = NETDEV_TX_BUSY;
319 bool again = false;
320
321 /* And release qdisc */
322 if (root_lock)
323 spin_unlock(root_lock);
324
325 /* Note that we validate skb (GSO, checksum, ...) outside of locks */
326 if (validate)
327 skb = validate_xmit_skb_list(skb, dev, &again);
328
329 #ifdef CONFIG_XFRM_OFFLOAD
330 if (unlikely(again)) {
331 if (root_lock)
332 spin_lock(root_lock);
333
334 dev_requeue_skb(skb, q);
335 return false;
336 }
337 #endif
338
339 if (likely(skb)) {
340 HARD_TX_LOCK(dev, txq, smp_processor_id());
341 if (!netif_xmit_frozen_or_stopped(txq))
342 skb = dev_hard_start_xmit(skb, dev, txq, &ret);
343 else
344 qdisc_maybe_clear_missed(q, txq);
345
346 HARD_TX_UNLOCK(dev, txq);
347 } else {
348 if (root_lock)
349 spin_lock(root_lock);
350 return true;
351 }
352
353 if (root_lock)
354 spin_lock(root_lock);
355
356 if (!dev_xmit_complete(ret)) {
357 /* Driver returned NETDEV_TX_BUSY - requeue skb */
358 if (unlikely(ret != NETDEV_TX_BUSY))
359 net_warn_ratelimited("BUG %s code %d qlen %d\n",
360 dev->name, ret, q->q.qlen);
361
362 dev_requeue_skb(skb, q);
363 return false;
364 }
365
366 return true;
367 }
368
369 /*
370 * NOTE: Called under qdisc_lock(q) with locally disabled BH.
371 *
372 * running seqcount guarantees only one CPU can process
373 * this qdisc at a time. qdisc_lock(q) serializes queue accesses for
374 * this queue.
375 *
376 * netif_tx_lock serializes accesses to device driver.
377 *
378 * qdisc_lock(q) and netif_tx_lock are mutually exclusive,
379 * if one is grabbed, another must be free.
380 *
381 * Note, that this procedure can be called by a watchdog timer
382 *
383 * Returns to the caller:
384 * 0 - queue is empty or throttled.
385 * >0 - queue is not empty.
386 *
387 */
388 static inline bool qdisc_restart(struct Qdisc *q, int *packets)
389 {
390 spinlock_t *root_lock = NULL;
391 struct netdev_queue *txq;
392 struct net_device *dev;
393 struct sk_buff *skb;
394 bool validate;
395
396 /* Dequeue packet */
397 skb = dequeue_skb(q, &validate, packets);
398 if (unlikely(!skb))
399 return false;
400
401 if (!(q->flags & TCQ_F_NOLOCK))
402 root_lock = qdisc_lock(q);
403
404 dev = qdisc_dev(q);
405 txq = skb_get_tx_queue(dev, skb);
406
407 return sch_direct_xmit(skb, q, dev, txq, root_lock, validate);
408 }
409
410 void __qdisc_run(struct Qdisc *q)
411 {
412 int quota = dev_tx_weight;
413 int packets;
414
415 while (qdisc_restart(q, &packets)) {
416 quota -= packets;
417 if (quota <= 0) {
418 if (q->flags & TCQ_F_NOLOCK)
419 set_bit(__QDISC_STATE_MISSED, &q->state);
420 else
421 __netif_schedule(q);
422
423 break;
424 }
425 }
426 }
427
428 unsigned long dev_trans_start(struct net_device *dev)
429 {
430 unsigned long val, res;
431 unsigned int i;
432
433 if (is_vlan_dev(dev))
434 dev = vlan_dev_real_dev(dev);
435 else if (netif_is_macvlan(dev))
436 dev = macvlan_dev_real_dev(dev);
437 res = netdev_get_tx_queue(dev, 0)->trans_start;
438 for (i = 1; i < dev->num_tx_queues; i++) {
439 val = netdev_get_tx_queue(dev, i)->trans_start;
440 if (val && time_after(val, res))
441 res = val;
442 }
443
444 return res;
445 }
446 EXPORT_SYMBOL(dev_trans_start);
447
448 static void dev_watchdog(struct timer_list *t)
449 {
450 struct net_device *dev = from_timer(dev, t, watchdog_timer);
451
452 netif_tx_lock(dev);
453 if (!qdisc_tx_is_noop(dev)) {
454 if (netif_device_present(dev) &&
455 netif_running(dev) &&
456 netif_carrier_ok(dev)) {
457 int some_queue_timedout = 0;
458 unsigned int i;
459 unsigned long trans_start;
460
461 for (i = 0; i < dev->num_tx_queues; i++) {
462 struct netdev_queue *txq;
463
464 txq = netdev_get_tx_queue(dev, i);
465 trans_start = txq->trans_start;
466 if (netif_xmit_stopped(txq) &&
467 time_after(jiffies, (trans_start +
468 dev->watchdog_timeo))) {
469 some_queue_timedout = 1;
470 txq->trans_timeout++;
471 break;
472 }
473 }
474
475 if (some_queue_timedout) {
476 trace_net_dev_xmit_timeout(dev, i);
477 WARN_ONCE(1, KERN_INFO "NETDEV WATCHDOG: %s (%s): transmit queue %u timed out\n",
478 dev->name, netdev_drivername(dev), i);
479 dev->netdev_ops->ndo_tx_timeout(dev, i);
480 }
481 if (!mod_timer(&dev->watchdog_timer,
482 round_jiffies(jiffies +
483 dev->watchdog_timeo)))
484 dev_hold(dev);
485 }
486 }
487 netif_tx_unlock(dev);
488
489 dev_put(dev);
490 }
491
492 void __netdev_watchdog_up(struct net_device *dev)
493 {
494 if (dev->netdev_ops->ndo_tx_timeout) {
495 if (dev->watchdog_timeo <= 0)
496 dev->watchdog_timeo = 5*HZ;
497 if (!mod_timer(&dev->watchdog_timer,
498 round_jiffies(jiffies + dev->watchdog_timeo)))
499 dev_hold(dev);
500 }
501 }
502 EXPORT_SYMBOL_GPL(__netdev_watchdog_up);
503
504 static void dev_watchdog_up(struct net_device *dev)
505 {
506 __netdev_watchdog_up(dev);
507 }
508
509 static void dev_watchdog_down(struct net_device *dev)
510 {
511 netif_tx_lock_bh(dev);
512 if (del_timer(&dev->watchdog_timer))
513 dev_put(dev);
514 netif_tx_unlock_bh(dev);
515 }
516
517 /**
518 * netif_carrier_on - set carrier
519 * @dev: network device
520 *
521 * Device has detected acquisition of carrier.
522 */
523 void netif_carrier_on(struct net_device *dev)
524 {
525 if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
526 if (dev->reg_state == NETREG_UNINITIALIZED)
527 return;
528 atomic_inc(&dev->carrier_up_count);
529 linkwatch_fire_event(dev);
530 if (netif_running(dev))
531 __netdev_watchdog_up(dev);
532 }
533 }
534 EXPORT_SYMBOL(netif_carrier_on);
535
536 /**
537 * netif_carrier_off - clear carrier
538 * @dev: network device
539 *
540 * Device has detected loss of carrier.
541 */
542 void netif_carrier_off(struct net_device *dev)
543 {
544 if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
545 if (dev->reg_state == NETREG_UNINITIALIZED)
546 return;
547 atomic_inc(&dev->carrier_down_count);
548 linkwatch_fire_event(dev);
549 }
550 }
551 EXPORT_SYMBOL(netif_carrier_off);
552
553 /**
554 * netif_carrier_event - report carrier state event
555 * @dev: network device
556 *
557 * Device has detected a carrier event but the carrier state wasn't changed.
558 * Use in drivers when querying carrier state asynchronously, to avoid missing
559 * events (link flaps) if link recovers before it's queried.
560 */
561 void netif_carrier_event(struct net_device *dev)
562 {
563 if (dev->reg_state == NETREG_UNINITIALIZED)
564 return;
565 atomic_inc(&dev->carrier_up_count);
566 atomic_inc(&dev->carrier_down_count);
567 linkwatch_fire_event(dev);
568 }
569 EXPORT_SYMBOL_GPL(netif_carrier_event);
570
571 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
572 under all circumstances. It is difficult to invent anything faster or
573 cheaper.
574 */
575
576 static int noop_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
577 struct sk_buff **to_free)
578 {
579 __qdisc_drop(skb, to_free);
580 return NET_XMIT_CN;
581 }
582
583 static struct sk_buff *noop_dequeue(struct Qdisc *qdisc)
584 {
585 return NULL;
586 }
587
588 struct Qdisc_ops noop_qdisc_ops __read_mostly = {
589 .id = "noop",
590 .priv_size = 0,
591 .enqueue = noop_enqueue,
592 .dequeue = noop_dequeue,
593 .peek = noop_dequeue,
594 .owner = THIS_MODULE,
595 };
596
597 static struct netdev_queue noop_netdev_queue = {
598 RCU_POINTER_INITIALIZER(qdisc, &noop_qdisc),
599 .qdisc_sleeping = &noop_qdisc,
600 };
601
602 struct Qdisc noop_qdisc = {
603 .enqueue = noop_enqueue,
604 .dequeue = noop_dequeue,
605 .flags = TCQ_F_BUILTIN,
606 .ops = &noop_qdisc_ops,
607 .q.lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
608 .dev_queue = &noop_netdev_queue,
609 .running = SEQCNT_ZERO(noop_qdisc.running),
610 .busylock = __SPIN_LOCK_UNLOCKED(noop_qdisc.busylock),
611 .gso_skb = {
612 .next = (struct sk_buff *)&noop_qdisc.gso_skb,
613 .prev = (struct sk_buff *)&noop_qdisc.gso_skb,
614 .qlen = 0,
615 .lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.gso_skb.lock),
616 },
617 .skb_bad_txq = {
618 .next = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
619 .prev = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
620 .qlen = 0,
621 .lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.skb_bad_txq.lock),
622 },
623 };
624 EXPORT_SYMBOL(noop_qdisc);
625
626 static int noqueue_init(struct Qdisc *qdisc, struct nlattr *opt,
627 struct netlink_ext_ack *extack)
628 {
629 /* register_qdisc() assigns a default of noop_enqueue if unset,
630 * but __dev_queue_xmit() treats noqueue only as such
631 * if this is NULL - so clear it here. */
632 qdisc->enqueue = NULL;
633 return 0;
634 }
635
636 struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
637 .id = "noqueue",
638 .priv_size = 0,
639 .init = noqueue_init,
640 .enqueue = noop_enqueue,
641 .dequeue = noop_dequeue,
642 .peek = noop_dequeue,
643 .owner = THIS_MODULE,
644 };
645
646 static const u8 prio2band[TC_PRIO_MAX + 1] = {
647 1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1
648 };
649
650 /* 3-band FIFO queue: old style, but should be a bit faster than
651 generic prio+fifo combination.
652 */
653
654 #define PFIFO_FAST_BANDS 3
655
656 /*
657 * Private data for a pfifo_fast scheduler containing:
658 * - rings for priority bands
659 */
660 struct pfifo_fast_priv {
661 struct skb_array q[PFIFO_FAST_BANDS];
662 };
663
664 static inline struct skb_array *band2list(struct pfifo_fast_priv *priv,
665 int band)
666 {
667 return &priv->q[band];
668 }
669
670 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
671 struct sk_buff **to_free)
672 {
673 int band = prio2band[skb->priority & TC_PRIO_MAX];
674 struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
675 struct skb_array *q = band2list(priv, band);
676 unsigned int pkt_len = qdisc_pkt_len(skb);
677 int err;
678
679 err = skb_array_produce(q, skb);
680
681 if (unlikely(err)) {
682 if (qdisc_is_percpu_stats(qdisc))
683 return qdisc_drop_cpu(skb, qdisc, to_free);
684 else
685 return qdisc_drop(skb, qdisc, to_free);
686 }
687
688 qdisc_update_stats_at_enqueue(qdisc, pkt_len);
689 return NET_XMIT_SUCCESS;
690 }
691
692 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc *qdisc)
693 {
694 struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
695 struct sk_buff *skb = NULL;
696 bool need_retry = true;
697 int band;
698
699 retry:
700 for (band = 0; band < PFIFO_FAST_BANDS && !skb; band++) {
701 struct skb_array *q = band2list(priv, band);
702
703 if (__skb_array_empty(q))
704 continue;
705
706 skb = __skb_array_consume(q);
707 }
708 if (likely(skb)) {
709 qdisc_update_stats_at_dequeue(qdisc, skb);
710 } else if (need_retry &&
711 READ_ONCE(qdisc->state) & QDISC_STATE_NON_EMPTY) {
712 /* Delay clearing the STATE_MISSED here to reduce
713 * the overhead of the second spin_trylock() in
714 * qdisc_run_begin() and __netif_schedule() calling
715 * in qdisc_run_end().
716 */
717 clear_bit(__QDISC_STATE_MISSED, &qdisc->state);
718 clear_bit(__QDISC_STATE_DRAINING, &qdisc->state);
719
720 /* Make sure dequeuing happens after clearing
721 * STATE_MISSED.
722 */
723 smp_mb__after_atomic();
724
725 need_retry = false;
726
727 goto retry;
728 }
729
730 return skb;
731 }
732
733 static struct sk_buff *pfifo_fast_peek(struct Qdisc *qdisc)
734 {
735 struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
736 struct sk_buff *skb = NULL;
737 int band;
738
739 for (band = 0; band < PFIFO_FAST_BANDS && !skb; band++) {
740 struct skb_array *q = band2list(priv, band);
741
742 skb = __skb_array_peek(q);
743 }
744
745 return skb;
746 }
747
748 static void pfifo_fast_reset(struct Qdisc *qdisc)
749 {
750 int i, band;
751 struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
752
753 for (band = 0; band < PFIFO_FAST_BANDS; band++) {
754 struct skb_array *q = band2list(priv, band);
755 struct sk_buff *skb;
756
757 /* NULL ring is possible if destroy path is due to a failed
758 * skb_array_init() in pfifo_fast_init() case.
759 */
760 if (!q->ring.queue)
761 continue;
762
763 while ((skb = __skb_array_consume(q)) != NULL)
764 kfree_skb(skb);
765 }
766
767 if (qdisc_is_percpu_stats(qdisc)) {
768 for_each_possible_cpu(i) {
769 struct gnet_stats_queue *q;
770
771 q = per_cpu_ptr(qdisc->cpu_qstats, i);
772 q->backlog = 0;
773 q->qlen = 0;
774 }
775 }
776 }
777
778 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
779 {
780 struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
781
782 memcpy(&opt.priomap, prio2band, TC_PRIO_MAX + 1);
783 if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
784 goto nla_put_failure;
785 return skb->len;
786
787 nla_put_failure:
788 return -1;
789 }
790
791 static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt,
792 struct netlink_ext_ack *extack)
793 {
794 unsigned int qlen = qdisc_dev(qdisc)->tx_queue_len;
795 struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
796 int prio;
797
798 /* guard against zero length rings */
799 if (!qlen)
800 return -EINVAL;
801
802 for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
803 struct skb_array *q = band2list(priv, prio);
804 int err;
805
806 err = skb_array_init(q, qlen, GFP_KERNEL);
807 if (err)
808 return -ENOMEM;
809 }
810
811 /* Can by-pass the queue discipline */
812 qdisc->flags |= TCQ_F_CAN_BYPASS;
813 return 0;
814 }
815
816 static void pfifo_fast_destroy(struct Qdisc *sch)
817 {
818 struct pfifo_fast_priv *priv = qdisc_priv(sch);
819 int prio;
820
821 for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
822 struct skb_array *q = band2list(priv, prio);
823
824 /* NULL ring is possible if destroy path is due to a failed
825 * skb_array_init() in pfifo_fast_init() case.
826 */
827 if (!q->ring.queue)
828 continue;
829 /* Destroy ring but no need to kfree_skb because a call to
830 * pfifo_fast_reset() has already done that work.
831 */
832 ptr_ring_cleanup(&q->ring, NULL);
833 }
834 }
835
836 static int pfifo_fast_change_tx_queue_len(struct Qdisc *sch,
837 unsigned int new_len)
838 {
839 struct pfifo_fast_priv *priv = qdisc_priv(sch);
840 struct skb_array *bands[PFIFO_FAST_BANDS];
841 int prio;
842
843 for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
844 struct skb_array *q = band2list(priv, prio);
845
846 bands[prio] = q;
847 }
848
849 return skb_array_resize_multiple(bands, PFIFO_FAST_BANDS, new_len,
850 GFP_KERNEL);
851 }
852
853 struct Qdisc_ops pfifo_fast_ops __read_mostly = {
854 .id = "pfifo_fast",
855 .priv_size = sizeof(struct pfifo_fast_priv),
856 .enqueue = pfifo_fast_enqueue,
857 .dequeue = pfifo_fast_dequeue,
858 .peek = pfifo_fast_peek,
859 .init = pfifo_fast_init,
860 .destroy = pfifo_fast_destroy,
861 .reset = pfifo_fast_reset,
862 .dump = pfifo_fast_dump,
863 .change_tx_queue_len = pfifo_fast_change_tx_queue_len,
864 .owner = THIS_MODULE,
865 .static_flags = TCQ_F_NOLOCK | TCQ_F_CPUSTATS,
866 };
867 EXPORT_SYMBOL(pfifo_fast_ops);
868
869 static struct lock_class_key qdisc_tx_busylock;
870 static struct lock_class_key qdisc_running_key;
871
872 struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
873 const struct Qdisc_ops *ops,
874 struct netlink_ext_ack *extack)
875 {
876 struct Qdisc *sch;
877 unsigned int size = sizeof(*sch) + ops->priv_size;
878 int err = -ENOBUFS;
879 struct net_device *dev;
880
881 if (!dev_queue) {
882 NL_SET_ERR_MSG(extack, "No device queue given");
883 err = -EINVAL;
884 goto errout;
885 }
886
887 dev = dev_queue->dev;
888 sch = kzalloc_node(size, GFP_KERNEL, netdev_queue_numa_node_read(dev_queue));
889
890 if (!sch)
891 goto errout;
892 __skb_queue_head_init(&sch->gso_skb);
893 __skb_queue_head_init(&sch->skb_bad_txq);
894 qdisc_skb_head_init(&sch->q);
895 spin_lock_init(&sch->q.lock);
896
897 if (ops->static_flags & TCQ_F_CPUSTATS) {
898 sch->cpu_bstats =
899 netdev_alloc_pcpu_stats(struct gnet_stats_basic_cpu);
900 if (!sch->cpu_bstats)
901 goto errout1;
902
903 sch->cpu_qstats = alloc_percpu(struct gnet_stats_queue);
904 if (!sch->cpu_qstats) {
905 free_percpu(sch->cpu_bstats);
906 goto errout1;
907 }
908 }
909
910 spin_lock_init(&sch->busylock);
911 lockdep_set_class(&sch->busylock,
912 dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
913
914 /* seqlock has the same scope of busylock, for NOLOCK qdisc */
915 spin_lock_init(&sch->seqlock);
916 lockdep_set_class(&sch->seqlock,
917 dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
918
919 seqcount_init(&sch->running);
920 lockdep_set_class(&sch->running,
921 dev->qdisc_running_key ?: &qdisc_running_key);
922
923 sch->ops = ops;
924 sch->flags = ops->static_flags;
925 sch->enqueue = ops->enqueue;
926 sch->dequeue = ops->dequeue;
927 sch->dev_queue = dev_queue;
928 dev_hold(dev);
929 refcount_set(&sch->refcnt, 1);
930
931 return sch;
932 errout1:
933 kfree(sch);
934 errout:
935 return ERR_PTR(err);
936 }
937
938 struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
939 const struct Qdisc_ops *ops,
940 unsigned int parentid,
941 struct netlink_ext_ack *extack)
942 {
943 struct Qdisc *sch;
944
945 if (!try_module_get(ops->owner)) {
946 NL_SET_ERR_MSG(extack, "Failed to increase module reference counter");
947 return NULL;
948 }
949
950 sch = qdisc_alloc(dev_queue, ops, extack);
951 if (IS_ERR(sch)) {
952 module_put(ops->owner);
953 return NULL;
954 }
955 sch->parent = parentid;
956
957 if (!ops->init || ops->init(sch, NULL, extack) == 0) {
958 trace_qdisc_create(ops, dev_queue->dev, parentid);
959 return sch;
960 }
961
962 qdisc_put(sch);
963 return NULL;
964 }
965 EXPORT_SYMBOL(qdisc_create_dflt);
966
967 /* Under qdisc_lock(qdisc) and BH! */
968
969 void qdisc_reset(struct Qdisc *qdisc)
970 {
971 const struct Qdisc_ops *ops = qdisc->ops;
972 struct sk_buff *skb, *tmp;
973
974 trace_qdisc_reset(qdisc);
975
976 if (ops->reset)
977 ops->reset(qdisc);
978
979 skb_queue_walk_safe(&qdisc->gso_skb, skb, tmp) {
980 __skb_unlink(skb, &qdisc->gso_skb);
981 kfree_skb_list(skb);
982 }
983
984 skb_queue_walk_safe(&qdisc->skb_bad_txq, skb, tmp) {
985 __skb_unlink(skb, &qdisc->skb_bad_txq);
986 kfree_skb_list(skb);
987 }
988
989 qdisc->q.qlen = 0;
990 qdisc->qstats.backlog = 0;
991 }
992 EXPORT_SYMBOL(qdisc_reset);
993
994 void qdisc_free(struct Qdisc *qdisc)
995 {
996 if (qdisc_is_percpu_stats(qdisc)) {
997 free_percpu(qdisc->cpu_bstats);
998 free_percpu(qdisc->cpu_qstats);
999 }
1000
1001 kfree(qdisc);
1002 }
1003
1004 static void qdisc_free_cb(struct rcu_head *head)
1005 {
1006 struct Qdisc *q = container_of(head, struct Qdisc, rcu);
1007
1008 qdisc_free(q);
1009 }
1010
1011 static void qdisc_destroy(struct Qdisc *qdisc)
1012 {
1013 const struct Qdisc_ops *ops = qdisc->ops;
1014
1015 #ifdef CONFIG_NET_SCHED
1016 qdisc_hash_del(qdisc);
1017
1018 qdisc_put_stab(rtnl_dereference(qdisc->stab));
1019 #endif
1020 gen_kill_estimator(&qdisc->rate_est);
1021
1022 qdisc_reset(qdisc);
1023
1024 if (ops->destroy)
1025 ops->destroy(qdisc);
1026
1027 module_put(ops->owner);
1028 dev_put(qdisc_dev(qdisc));
1029
1030 trace_qdisc_destroy(qdisc);
1031
1032 call_rcu(&qdisc->rcu, qdisc_free_cb);
1033 }
1034
1035 void qdisc_put(struct Qdisc *qdisc)
1036 {
1037 if (!qdisc)
1038 return;
1039
1040 if (qdisc->flags & TCQ_F_BUILTIN ||
1041 !refcount_dec_and_test(&qdisc->refcnt))
1042 return;
1043
1044 qdisc_destroy(qdisc);
1045 }
1046 EXPORT_SYMBOL(qdisc_put);
1047
1048 /* Version of qdisc_put() that is called with rtnl mutex unlocked.
1049 * Intended to be used as optimization, this function only takes rtnl lock if
1050 * qdisc reference counter reached zero.
1051 */
1052
1053 void qdisc_put_unlocked(struct Qdisc *qdisc)
1054 {
1055 if (qdisc->flags & TCQ_F_BUILTIN ||
1056 !refcount_dec_and_rtnl_lock(&qdisc->refcnt))
1057 return;
1058
1059 qdisc_destroy(qdisc);
1060 rtnl_unlock();
1061 }
1062 EXPORT_SYMBOL(qdisc_put_unlocked);
1063
1064 /* Attach toplevel qdisc to device queue. */
1065 struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
1066 struct Qdisc *qdisc)
1067 {
1068 struct Qdisc *oqdisc = dev_queue->qdisc_sleeping;
1069 spinlock_t *root_lock;
1070
1071 root_lock = qdisc_lock(oqdisc);
1072 spin_lock_bh(root_lock);
1073
1074 /* ... and graft new one */
1075 if (qdisc == NULL)
1076 qdisc = &noop_qdisc;
1077 dev_queue->qdisc_sleeping = qdisc;
1078 rcu_assign_pointer(dev_queue->qdisc, &noop_qdisc);
1079
1080 spin_unlock_bh(root_lock);
1081
1082 return oqdisc;
1083 }
1084 EXPORT_SYMBOL(dev_graft_qdisc);
1085
1086 static void attach_one_default_qdisc(struct net_device *dev,
1087 struct netdev_queue *dev_queue,
1088 void *_unused)
1089 {
1090 struct Qdisc *qdisc;
1091 const struct Qdisc_ops *ops = default_qdisc_ops;
1092
1093 if (dev->priv_flags & IFF_NO_QUEUE)
1094 ops = &noqueue_qdisc_ops;
1095 else if(dev->type == ARPHRD_CAN)
1096 ops = &pfifo_fast_ops;
1097
1098 qdisc = qdisc_create_dflt(dev_queue, ops, TC_H_ROOT, NULL);
1099 if (!qdisc)
1100 return;
1101
1102 if (!netif_is_multiqueue(dev))
1103 qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
1104 dev_queue->qdisc_sleeping = qdisc;
1105 }
1106
1107 static void attach_default_qdiscs(struct net_device *dev)
1108 {
1109 struct netdev_queue *txq;
1110 struct Qdisc *qdisc;
1111
1112 txq = netdev_get_tx_queue(dev, 0);
1113
1114 if (!netif_is_multiqueue(dev) ||
1115 dev->priv_flags & IFF_NO_QUEUE) {
1116 netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
1117 qdisc = txq->qdisc_sleeping;
1118 rcu_assign_pointer(dev->qdisc, qdisc);
1119 qdisc_refcount_inc(qdisc);
1120 } else {
1121 qdisc = qdisc_create_dflt(txq, &mq_qdisc_ops, TC_H_ROOT, NULL);
1122 if (qdisc) {
1123 rcu_assign_pointer(dev->qdisc, qdisc);
1124 qdisc->ops->attach(qdisc);
1125 }
1126 }
1127 qdisc = rtnl_dereference(dev->qdisc);
1128
1129 /* Detect default qdisc setup/init failed and fallback to "noqueue" */
1130 if (qdisc == &noop_qdisc) {
1131 netdev_warn(dev, "default qdisc (%s) fail, fallback to %s\n",
1132 default_qdisc_ops->id, noqueue_qdisc_ops.id);
1133 dev->priv_flags |= IFF_NO_QUEUE;
1134 netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
1135 qdisc = txq->qdisc_sleeping;
1136 rcu_assign_pointer(dev->qdisc, qdisc);
1137 qdisc_refcount_inc(qdisc);
1138 dev->priv_flags ^= IFF_NO_QUEUE;
1139 }
1140
1141 #ifdef CONFIG_NET_SCHED
1142 if (qdisc != &noop_qdisc)
1143 qdisc_hash_add(qdisc, false);
1144 #endif
1145 }
1146
1147 static void transition_one_qdisc(struct net_device *dev,
1148 struct netdev_queue *dev_queue,
1149 void *_need_watchdog)
1150 {
1151 struct Qdisc *new_qdisc = dev_queue->qdisc_sleeping;
1152 int *need_watchdog_p = _need_watchdog;
1153
1154 if (!(new_qdisc->flags & TCQ_F_BUILTIN))
1155 clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state);
1156
1157 rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
1158 if (need_watchdog_p) {
1159 dev_queue->trans_start = 0;
1160 *need_watchdog_p = 1;
1161 }
1162 }
1163
1164 void dev_activate(struct net_device *dev)
1165 {
1166 int need_watchdog;
1167
1168 /* No queueing discipline is attached to device;
1169 * create default one for devices, which need queueing
1170 * and noqueue_qdisc for virtual interfaces
1171 */
1172
1173 if (rtnl_dereference(dev->qdisc) == &noop_qdisc)
1174 attach_default_qdiscs(dev);
1175
1176 if (!netif_carrier_ok(dev))
1177 /* Delay activation until next carrier-on event */
1178 return;
1179
1180 need_watchdog = 0;
1181 netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
1182 if (dev_ingress_queue(dev))
1183 transition_one_qdisc(dev, dev_ingress_queue(dev), NULL);
1184
1185 if (need_watchdog) {
1186 netif_trans_update(dev);
1187 dev_watchdog_up(dev);
1188 }
1189 }
1190 EXPORT_SYMBOL(dev_activate);
1191
1192 static void qdisc_deactivate(struct Qdisc *qdisc)
1193 {
1194 if (qdisc->flags & TCQ_F_BUILTIN)
1195 return;
1196
1197 set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
1198 }
1199
1200 static void dev_deactivate_queue(struct net_device *dev,
1201 struct netdev_queue *dev_queue,
1202 void *_qdisc_default)
1203 {
1204 struct Qdisc *qdisc_default = _qdisc_default;
1205 struct Qdisc *qdisc;
1206
1207 qdisc = rtnl_dereference(dev_queue->qdisc);
1208 if (qdisc) {
1209 qdisc_deactivate(qdisc);
1210 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
1211 }
1212 }
1213
1214 static void dev_reset_queue(struct net_device *dev,
1215 struct netdev_queue *dev_queue,
1216 void *_unused)
1217 {
1218 struct Qdisc *qdisc;
1219 bool nolock;
1220
1221 qdisc = dev_queue->qdisc_sleeping;
1222 if (!qdisc)
1223 return;
1224
1225 nolock = qdisc->flags & TCQ_F_NOLOCK;
1226
1227 if (nolock)
1228 spin_lock_bh(&qdisc->seqlock);
1229 spin_lock_bh(qdisc_lock(qdisc));
1230
1231 qdisc_reset(qdisc);
1232
1233 spin_unlock_bh(qdisc_lock(qdisc));
1234 if (nolock) {
1235 clear_bit(__QDISC_STATE_MISSED, &qdisc->state);
1236 clear_bit(__QDISC_STATE_DRAINING, &qdisc->state);
1237 spin_unlock_bh(&qdisc->seqlock);
1238 }
1239 }
1240
1241 static bool some_qdisc_is_busy(struct net_device *dev)
1242 {
1243 unsigned int i;
1244
1245 for (i = 0; i < dev->num_tx_queues; i++) {
1246 struct netdev_queue *dev_queue;
1247 spinlock_t *root_lock;
1248 struct Qdisc *q;
1249 int val;
1250
1251 dev_queue = netdev_get_tx_queue(dev, i);
1252 q = dev_queue->qdisc_sleeping;
1253
1254 root_lock = qdisc_lock(q);
1255 spin_lock_bh(root_lock);
1256
1257 val = (qdisc_is_running(q) ||
1258 test_bit(__QDISC_STATE_SCHED, &q->state));
1259
1260 spin_unlock_bh(root_lock);
1261
1262 if (val)
1263 return true;
1264 }
1265 return false;
1266 }
1267
1268 /**
1269 * dev_deactivate_many - deactivate transmissions on several devices
1270 * @head: list of devices to deactivate
1271 *
1272 * This function returns only when all outstanding transmissions
1273 * have completed, unless all devices are in dismantle phase.
1274 */
1275 void dev_deactivate_many(struct list_head *head)
1276 {
1277 struct net_device *dev;
1278
1279 list_for_each_entry(dev, head, close_list) {
1280 netdev_for_each_tx_queue(dev, dev_deactivate_queue,
1281 &noop_qdisc);
1282 if (dev_ingress_queue(dev))
1283 dev_deactivate_queue(dev, dev_ingress_queue(dev),
1284 &noop_qdisc);
1285
1286 dev_watchdog_down(dev);
1287 }
1288
1289 /* Wait for outstanding qdisc-less dev_queue_xmit calls or
1290 * outstanding qdisc enqueuing calls.
1291 * This is avoided if all devices are in dismantle phase :
1292 * Caller will call synchronize_net() for us
1293 */
1294 synchronize_net();
1295
1296 list_for_each_entry(dev, head, close_list) {
1297 netdev_for_each_tx_queue(dev, dev_reset_queue, NULL);
1298
1299 if (dev_ingress_queue(dev))
1300 dev_reset_queue(dev, dev_ingress_queue(dev), NULL);
1301 }
1302
1303 /* Wait for outstanding qdisc_run calls. */
1304 list_for_each_entry(dev, head, close_list) {
1305 while (some_qdisc_is_busy(dev)) {
1306 /* wait_event() would avoid this sleep-loop but would
1307 * require expensive checks in the fast paths of packet
1308 * processing which isn't worth it.
1309 */
1310 schedule_timeout_uninterruptible(1);
1311 }
1312 }
1313 }
1314
1315 void dev_deactivate(struct net_device *dev)
1316 {
1317 LIST_HEAD(single);
1318
1319 list_add(&dev->close_list, &single);
1320 dev_deactivate_many(&single);
1321 list_del(&single);
1322 }
1323 EXPORT_SYMBOL(dev_deactivate);
1324
1325 static int qdisc_change_tx_queue_len(struct net_device *dev,
1326 struct netdev_queue *dev_queue)
1327 {
1328 struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
1329 const struct Qdisc_ops *ops = qdisc->ops;
1330
1331 if (ops->change_tx_queue_len)
1332 return ops->change_tx_queue_len(qdisc, dev->tx_queue_len);
1333 return 0;
1334 }
1335
1336 void dev_qdisc_change_real_num_tx(struct net_device *dev,
1337 unsigned int new_real_tx)
1338 {
1339 struct Qdisc *qdisc = rtnl_dereference(dev->qdisc);
1340
1341 if (qdisc->ops->change_real_num_tx)
1342 qdisc->ops->change_real_num_tx(qdisc, new_real_tx);
1343 }
1344
1345 int dev_qdisc_change_tx_queue_len(struct net_device *dev)
1346 {
1347 bool up = dev->flags & IFF_UP;
1348 unsigned int i;
1349 int ret = 0;
1350
1351 if (up)
1352 dev_deactivate(dev);
1353
1354 for (i = 0; i < dev->num_tx_queues; i++) {
1355 ret = qdisc_change_tx_queue_len(dev, &dev->_tx[i]);
1356
1357 /* TODO: revert changes on a partial failure */
1358 if (ret)
1359 break;
1360 }
1361
1362 if (up)
1363 dev_activate(dev);
1364 return ret;
1365 }
1366
1367 static void dev_init_scheduler_queue(struct net_device *dev,
1368 struct netdev_queue *dev_queue,
1369 void *_qdisc)
1370 {
1371 struct Qdisc *qdisc = _qdisc;
1372
1373 rcu_assign_pointer(dev_queue->qdisc, qdisc);
1374 dev_queue->qdisc_sleeping = qdisc;
1375 }
1376
1377 void dev_init_scheduler(struct net_device *dev)
1378 {
1379 rcu_assign_pointer(dev->qdisc, &noop_qdisc);
1380 netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
1381 if (dev_ingress_queue(dev))
1382 dev_init_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
1383
1384 timer_setup(&dev->watchdog_timer, dev_watchdog, 0);
1385 }
1386
1387 static void shutdown_scheduler_queue(struct net_device *dev,
1388 struct netdev_queue *dev_queue,
1389 void *_qdisc_default)
1390 {
1391 struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
1392 struct Qdisc *qdisc_default = _qdisc_default;
1393
1394 if (qdisc) {
1395 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
1396 dev_queue->qdisc_sleeping = qdisc_default;
1397
1398 qdisc_put(qdisc);
1399 }
1400 }
1401
1402 void dev_shutdown(struct net_device *dev)
1403 {
1404 netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
1405 if (dev_ingress_queue(dev))
1406 shutdown_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
1407 qdisc_put(rtnl_dereference(dev->qdisc));
1408 rcu_assign_pointer(dev->qdisc, &noop_qdisc);
1409
1410 WARN_ON(timer_pending(&dev->watchdog_timer));
1411 }
1412
1413 /**
1414 * psched_ratecfg_precompute__() - Pre-compute values for reciprocal division
1415 * @rate: Rate to compute reciprocal division values of
1416 * @mult: Multiplier for reciprocal division
1417 * @shift: Shift for reciprocal division
1418 *
1419 * The multiplier and shift for reciprocal division by rate are stored
1420 * in mult and shift.
1421 *
1422 * The deal here is to replace a divide by a reciprocal one
1423 * in fast path (a reciprocal divide is a multiply and a shift)
1424 *
1425 * Normal formula would be :
1426 * time_in_ns = (NSEC_PER_SEC * len) / rate_bps
1427 *
1428 * We compute mult/shift to use instead :
1429 * time_in_ns = (len * mult) >> shift;
1430 *
1431 * We try to get the highest possible mult value for accuracy,
1432 * but have to make sure no overflows will ever happen.
1433 *
1434 * reciprocal_value() is not used here it doesn't handle 64-bit values.
1435 */
1436 static void psched_ratecfg_precompute__(u64 rate, u32 *mult, u8 *shift)
1437 {
1438 u64 factor = NSEC_PER_SEC;
1439
1440 *mult = 1;
1441 *shift = 0;
1442
1443 if (rate <= 0)
1444 return;
1445
1446 for (;;) {
1447 *mult = div64_u64(factor, rate);
1448 if (*mult & (1U << 31) || factor & (1ULL << 63))
1449 break;
1450 factor <<= 1;
1451 (*shift)++;
1452 }
1453 }
1454
1455 void psched_ratecfg_precompute(struct psched_ratecfg *r,
1456 const struct tc_ratespec *conf,
1457 u64 rate64)
1458 {
1459 memset(r, 0, sizeof(*r));
1460 r->overhead = conf->overhead;
1461 r->mpu = conf->mpu;
1462 r->rate_bytes_ps = max_t(u64, conf->rate, rate64);
1463 r->linklayer = (conf->linklayer & TC_LINKLAYER_MASK);
1464 psched_ratecfg_precompute__(r->rate_bytes_ps, &r->mult, &r->shift);
1465 }
1466 EXPORT_SYMBOL(psched_ratecfg_precompute);
1467
1468 void psched_ppscfg_precompute(struct psched_pktrate *r, u64 pktrate64)
1469 {
1470 r->rate_pkts_ps = pktrate64;
1471 psched_ratecfg_precompute__(r->rate_pkts_ps, &r->mult, &r->shift);
1472 }
1473 EXPORT_SYMBOL(psched_ppscfg_precompute);
1474
1475 static void mini_qdisc_rcu_func(struct rcu_head *head)
1476 {
1477 }
1478
1479 void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp,
1480 struct tcf_proto *tp_head)
1481 {
1482 /* Protected with chain0->filter_chain_lock.
1483 * Can't access chain directly because tp_head can be NULL.
1484 */
1485 struct mini_Qdisc *miniq_old =
1486 rcu_dereference_protected(*miniqp->p_miniq, 1);
1487 struct mini_Qdisc *miniq;
1488
1489 if (!tp_head) {
1490 RCU_INIT_POINTER(*miniqp->p_miniq, NULL);
1491 /* Wait for flying RCU callback before it is freed. */
1492 rcu_barrier();
1493 return;
1494 }
1495
1496 miniq = !miniq_old || miniq_old == &miniqp->miniq2 ?
1497 &miniqp->miniq1 : &miniqp->miniq2;
1498
1499 /* We need to make sure that readers won't see the miniq
1500 * we are about to modify. So wait until previous call_rcu callback
1501 * is done.
1502 */
1503 rcu_barrier();
1504 miniq->filter_list = tp_head;
1505 rcu_assign_pointer(*miniqp->p_miniq, miniq);
1506
1507 if (miniq_old)
1508 /* This is counterpart of the rcu barriers above. We need to
1509 * block potential new user of miniq_old until all readers
1510 * are not seeing it.
1511 */
1512 call_rcu(&miniq_old->rcu, mini_qdisc_rcu_func);
1513 }
1514 EXPORT_SYMBOL(mini_qdisc_pair_swap);
1515
1516 void mini_qdisc_pair_block_init(struct mini_Qdisc_pair *miniqp,
1517 struct tcf_block *block)
1518 {
1519 miniqp->miniq1.block = block;
1520 miniqp->miniq2.block = block;
1521 }
1522 EXPORT_SYMBOL(mini_qdisc_pair_block_init);
1523
1524 void mini_qdisc_pair_init(struct mini_Qdisc_pair *miniqp, struct Qdisc *qdisc,
1525 struct mini_Qdisc __rcu **p_miniq)
1526 {
1527 miniqp->miniq1.cpu_bstats = qdisc->cpu_bstats;
1528 miniqp->miniq1.cpu_qstats = qdisc->cpu_qstats;
1529 miniqp->miniq2.cpu_bstats = qdisc->cpu_bstats;
1530 miniqp->miniq2.cpu_qstats = qdisc->cpu_qstats;
1531 miniqp->p_miniq = p_miniq;
1532 }
1533 EXPORT_SYMBOL(mini_qdisc_pair_init);
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