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 */
35const struct Qdisc_ops *default_qdisc_ops = &pfifo_fast_ops;
36EXPORT_SYMBOL(default_qdisc_ops);
37
38static void qdisc_maybe_clear_missed(struct Qdisc *q,
39 const struct netdev_queue *txq)
40{
41 clear_bit(nr: __QDISC_STATE_MISSED, addr: &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(dev_queue: txq))
54 set_bit(nr: __QDISC_STATE_MISSED, addr: &q->state);
55 else
56 set_bit(nr: __QDISC_STATE_DRAINING, addr: &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
72static 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(qdisc: q);
80 spin_lock(lock);
81 }
82
83 skb = skb_peek(list_: &q->skb_bad_txq);
84 if (skb) {
85 /* check the reason of requeuing without tx lock first */
86 txq = skb_get_tx_queue(dev: txq->dev, skb);
87 if (!netif_xmit_frozen_or_stopped(dev_queue: txq)) {
88 skb = __skb_dequeue(list: &q->skb_bad_txq);
89 if (qdisc_is_percpu_stats(q)) {
90 qdisc_qstats_cpu_backlog_dec(sch: q, skb);
91 qdisc_qstats_cpu_qlen_dec(sch: q);
92 } else {
93 qdisc_qstats_backlog_dec(sch: 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
108static inline struct sk_buff *qdisc_dequeue_skb_bad_txq(struct Qdisc *q)
109{
110 struct sk_buff *skb = skb_peek(list_: &q->skb_bad_txq);
111
112 if (unlikely(skb))
113 skb = __skb_dequeue_bad_txq(q);
114
115 return skb;
116}
117
118static 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(qdisc: q);
125 spin_lock(lock);
126 }
127
128 __skb_queue_tail(list: &q->skb_bad_txq, newsk: skb);
129
130 if (qdisc_is_percpu_stats(q)) {
131 qdisc_qstats_cpu_backlog_inc(sch: q, skb);
132 qdisc_qstats_cpu_qlen_inc(sch: q);
133 } else {
134 qdisc_qstats_backlog_inc(sch: q, skb);
135 q->q.qlen++;
136 }
137
138 if (lock)
139 spin_unlock(lock);
140}
141
142static 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(qdisc: q);
148 spin_lock(lock);
149 }
150
151 while (skb) {
152 struct sk_buff *next = skb->next;
153
154 __skb_queue_tail(list: &q->gso_skb, newsk: skb);
155
156 /* it's still part of the queue */
157 if (qdisc_is_percpu_stats(q)) {
158 qdisc_qstats_cpu_requeues_inc(sch: q);
159 qdisc_qstats_cpu_backlog_inc(sch: q, skb);
160 qdisc_qstats_cpu_qlen_inc(sch: q);
161 } else {
162 q->qstats.requeues++;
163 qdisc_qstats_backlog_inc(sch: q, skb);
164 q->q.qlen++;
165 }
166
167 skb = next;
168 }
169
170 if (lock) {
171 spin_unlock(lock);
172 set_bit(nr: __QDISC_STATE_MISSED, addr: &q->state);
173 } else {
174 __netif_schedule(q);
175 }
176}
177
178static 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 */
202static 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, skb: 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 */
228static 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(qdisc: q);
240 spin_lock(lock);
241 }
242
243 skb = skb_peek(list_: &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(dev: txq->dev, skb);
260 if (!netif_xmit_frozen_or_stopped(dev_queue: txq)) {
261 skb = __skb_dequeue(list: &q->gso_skb);
262 if (qdisc_is_percpu_stats(q)) {
263 qdisc_qstats_cpu_backlog_dec(sch: q, skb);
264 qdisc_qstats_cpu_qlen_dec(sch: q);
265 } else {
266 qdisc_qstats_backlog_dec(sch: 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 }
277validate:
278 *validate = true;
279
280 if ((q->flags & TCQ_F_ONETXQUEUE) &&
281 netif_xmit_frozen_or_stopped(dev_queue: 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) {
294bulk:
295 if (qdisc_may_bulk(qdisc: q))
296 try_bulk_dequeue_skb(q, skb, txq, packets);
297 else
298 try_bulk_dequeue_skb_slow(q, skb, packets);
299 }
300trace:
301 trace_qdisc_dequeue(qdisc: q, txq, packets: *packets, skb);
302 return skb;
303}
304
305/*
306 * Transmit possibly several skbs, and handle the return status as
307 * required. Owning qdisc running bit guarantees that only one CPU
308 * 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 */
314bool 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(lock: 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: &again);
328
329#ifdef CONFIG_XFRM_OFFLOAD
330 if (unlikely(again)) {
331 if (root_lock)
332 spin_lock(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(dev_queue: txq))
342 skb = dev_hard_start_xmit(skb, dev, txq, ret: &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(lock: root_lock);
350 return true;
351 }
352
353 if (root_lock)
354 spin_lock(lock: root_lock);
355
356 if (!dev_xmit_complete(rc: 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 */
388static 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: &validate, packets);
398 if (unlikely(!skb))
399 return false;
400
401 if (!(q->flags & TCQ_F_NOLOCK))
402 root_lock = qdisc_lock(qdisc: q);
403
404 dev = qdisc_dev(qdisc: q);
405 txq = skb_get_tx_queue(dev, skb);
406
407 return sch_direct_xmit(skb, q, dev, txq, root_lock, validate);
408}
409
410void __qdisc_run(struct Qdisc *q)
411{
412 int quota = READ_ONCE(dev_tx_weight);
413 int packets;
414
415 while (qdisc_restart(q, packets: &packets)) {
416 quota -= packets;
417 if (quota <= 0) {
418 if (q->flags & TCQ_F_NOLOCK)
419 set_bit(nr: __QDISC_STATE_MISSED, addr: &q->state);
420 else
421 __netif_schedule(q);
422
423 break;
424 }
425 }
426}
427
428unsigned long dev_trans_start(struct net_device *dev)
429{
430 unsigned long res = READ_ONCE(netdev_get_tx_queue(dev, 0)->trans_start);
431 unsigned long val;
432 unsigned int i;
433
434 for (i = 1; i < dev->num_tx_queues; i++) {
435 val = READ_ONCE(netdev_get_tx_queue(dev, i)->trans_start);
436 if (val && time_after(val, res))
437 res = val;
438 }
439
440 return res;
441}
442EXPORT_SYMBOL(dev_trans_start);
443
444static void netif_freeze_queues(struct net_device *dev)
445{
446 unsigned int i;
447 int cpu;
448
449 cpu = smp_processor_id();
450 for (i = 0; i < dev->num_tx_queues; i++) {
451 struct netdev_queue *txq = netdev_get_tx_queue(dev, index: i);
452
453 /* We are the only thread of execution doing a
454 * freeze, but we have to grab the _xmit_lock in
455 * order to synchronize with threads which are in
456 * the ->hard_start_xmit() handler and already
457 * checked the frozen bit.
458 */
459 __netif_tx_lock(txq, cpu);
460 set_bit(nr: __QUEUE_STATE_FROZEN, addr: &txq->state);
461 __netif_tx_unlock(txq);
462 }
463}
464
465void netif_tx_lock(struct net_device *dev)
466{
467 spin_lock(lock: &dev->tx_global_lock);
468 netif_freeze_queues(dev);
469}
470EXPORT_SYMBOL(netif_tx_lock);
471
472static void netif_unfreeze_queues(struct net_device *dev)
473{
474 unsigned int i;
475
476 for (i = 0; i < dev->num_tx_queues; i++) {
477 struct netdev_queue *txq = netdev_get_tx_queue(dev, index: i);
478
479 /* No need to grab the _xmit_lock here. If the
480 * queue is not stopped for another reason, we
481 * force a schedule.
482 */
483 clear_bit(nr: __QUEUE_STATE_FROZEN, addr: &txq->state);
484 netif_schedule_queue(txq);
485 }
486}
487
488void netif_tx_unlock(struct net_device *dev)
489{
490 netif_unfreeze_queues(dev);
491 spin_unlock(lock: &dev->tx_global_lock);
492}
493EXPORT_SYMBOL(netif_tx_unlock);
494
495static void dev_watchdog(struct timer_list *t)
496{
497 struct net_device *dev = from_timer(dev, t, watchdog_timer);
498 bool release = true;
499
500 spin_lock(lock: &dev->tx_global_lock);
501 if (!qdisc_tx_is_noop(dev)) {
502 if (netif_device_present(dev) &&
503 netif_running(dev) &&
504 netif_carrier_ok(dev)) {
505 unsigned int timedout_ms = 0;
506 unsigned int i;
507 unsigned long trans_start;
508
509 for (i = 0; i < dev->num_tx_queues; i++) {
510 struct netdev_queue *txq;
511
512 txq = netdev_get_tx_queue(dev, index: i);
513 trans_start = READ_ONCE(txq->trans_start);
514 if (netif_xmit_stopped(dev_queue: txq) &&
515 time_after(jiffies, (trans_start +
516 dev->watchdog_timeo))) {
517 timedout_ms = jiffies_to_msecs(j: jiffies - trans_start);
518 atomic_long_inc(v: &txq->trans_timeout);
519 break;
520 }
521 }
522
523 if (unlikely(timedout_ms)) {
524 trace_net_dev_xmit_timeout(dev, queue_index: i);
525 WARN_ONCE(1, "NETDEV WATCHDOG: %s (%s): transmit queue %u timed out %u ms\n",
526 dev->name, netdev_drivername(dev), i, timedout_ms);
527 netif_freeze_queues(dev);
528 dev->netdev_ops->ndo_tx_timeout(dev, i);
529 netif_unfreeze_queues(dev);
530 }
531 if (!mod_timer(timer: &dev->watchdog_timer,
532 expires: round_jiffies(j: jiffies +
533 dev->watchdog_timeo)))
534 release = false;
535 }
536 }
537 spin_unlock(lock: &dev->tx_global_lock);
538
539 if (release)
540 netdev_put(dev, tracker: &dev->watchdog_dev_tracker);
541}
542
543void __netdev_watchdog_up(struct net_device *dev)
544{
545 if (dev->netdev_ops->ndo_tx_timeout) {
546 if (dev->watchdog_timeo <= 0)
547 dev->watchdog_timeo = 5*HZ;
548 if (!mod_timer(timer: &dev->watchdog_timer,
549 expires: round_jiffies(j: jiffies + dev->watchdog_timeo)))
550 netdev_hold(dev, tracker: &dev->watchdog_dev_tracker,
551 GFP_ATOMIC);
552 }
553}
554EXPORT_SYMBOL_GPL(__netdev_watchdog_up);
555
556static void dev_watchdog_up(struct net_device *dev)
557{
558 __netdev_watchdog_up(dev);
559}
560
561static void dev_watchdog_down(struct net_device *dev)
562{
563 netif_tx_lock_bh(dev);
564 if (del_timer(timer: &dev->watchdog_timer))
565 netdev_put(dev, tracker: &dev->watchdog_dev_tracker);
566 netif_tx_unlock_bh(dev);
567}
568
569/**
570 * netif_carrier_on - set carrier
571 * @dev: network device
572 *
573 * Device has detected acquisition of carrier.
574 */
575void netif_carrier_on(struct net_device *dev)
576{
577 if (test_and_clear_bit(nr: __LINK_STATE_NOCARRIER, addr: &dev->state)) {
578 if (dev->reg_state == NETREG_UNINITIALIZED)
579 return;
580 atomic_inc(v: &dev->carrier_up_count);
581 linkwatch_fire_event(dev);
582 if (netif_running(dev))
583 __netdev_watchdog_up(dev);
584 }
585}
586EXPORT_SYMBOL(netif_carrier_on);
587
588/**
589 * netif_carrier_off - clear carrier
590 * @dev: network device
591 *
592 * Device has detected loss of carrier.
593 */
594void netif_carrier_off(struct net_device *dev)
595{
596 if (!test_and_set_bit(nr: __LINK_STATE_NOCARRIER, addr: &dev->state)) {
597 if (dev->reg_state == NETREG_UNINITIALIZED)
598 return;
599 atomic_inc(v: &dev->carrier_down_count);
600 linkwatch_fire_event(dev);
601 }
602}
603EXPORT_SYMBOL(netif_carrier_off);
604
605/**
606 * netif_carrier_event - report carrier state event
607 * @dev: network device
608 *
609 * Device has detected a carrier event but the carrier state wasn't changed.
610 * Use in drivers when querying carrier state asynchronously, to avoid missing
611 * events (link flaps) if link recovers before it's queried.
612 */
613void netif_carrier_event(struct net_device *dev)
614{
615 if (dev->reg_state == NETREG_UNINITIALIZED)
616 return;
617 atomic_inc(v: &dev->carrier_up_count);
618 atomic_inc(v: &dev->carrier_down_count);
619 linkwatch_fire_event(dev);
620}
621EXPORT_SYMBOL_GPL(netif_carrier_event);
622
623/* "NOOP" scheduler: the best scheduler, recommended for all interfaces
624 under all circumstances. It is difficult to invent anything faster or
625 cheaper.
626 */
627
628static int noop_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
629 struct sk_buff **to_free)
630{
631 __qdisc_drop(skb, to_free);
632 return NET_XMIT_CN;
633}
634
635static struct sk_buff *noop_dequeue(struct Qdisc *qdisc)
636{
637 return NULL;
638}
639
640struct Qdisc_ops noop_qdisc_ops __read_mostly = {
641 .id = "noop",
642 .priv_size = 0,
643 .enqueue = noop_enqueue,
644 .dequeue = noop_dequeue,
645 .peek = noop_dequeue,
646 .owner = THIS_MODULE,
647};
648
649static struct netdev_queue noop_netdev_queue = {
650 RCU_POINTER_INITIALIZER(qdisc, &noop_qdisc),
651 RCU_POINTER_INITIALIZER(qdisc_sleeping, &noop_qdisc),
652};
653
654struct Qdisc noop_qdisc = {
655 .enqueue = noop_enqueue,
656 .dequeue = noop_dequeue,
657 .flags = TCQ_F_BUILTIN,
658 .ops = &noop_qdisc_ops,
659 .q.lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
660 .dev_queue = &noop_netdev_queue,
661 .busylock = __SPIN_LOCK_UNLOCKED(noop_qdisc.busylock),
662 .gso_skb = {
663 .next = (struct sk_buff *)&noop_qdisc.gso_skb,
664 .prev = (struct sk_buff *)&noop_qdisc.gso_skb,
665 .qlen = 0,
666 .lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.gso_skb.lock),
667 },
668 .skb_bad_txq = {
669 .next = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
670 .prev = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
671 .qlen = 0,
672 .lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.skb_bad_txq.lock),
673 },
674};
675EXPORT_SYMBOL(noop_qdisc);
676
677static int noqueue_init(struct Qdisc *qdisc, struct nlattr *opt,
678 struct netlink_ext_ack *extack)
679{
680 /* register_qdisc() assigns a default of noop_enqueue if unset,
681 * but __dev_queue_xmit() treats noqueue only as such
682 * if this is NULL - so clear it here. */
683 qdisc->enqueue = NULL;
684 return 0;
685}
686
687struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
688 .id = "noqueue",
689 .priv_size = 0,
690 .init = noqueue_init,
691 .enqueue = noop_enqueue,
692 .dequeue = noop_dequeue,
693 .peek = noop_dequeue,
694 .owner = THIS_MODULE,
695};
696
697const u8 sch_default_prio2band[TC_PRIO_MAX + 1] = {
698 1, 2, 2, 2, 1, 2, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1
699};
700EXPORT_SYMBOL(sch_default_prio2band);
701
702/* 3-band FIFO queue: old style, but should be a bit faster than
703 generic prio+fifo combination.
704 */
705
706#define PFIFO_FAST_BANDS 3
707
708/*
709 * Private data for a pfifo_fast scheduler containing:
710 * - rings for priority bands
711 */
712struct pfifo_fast_priv {
713 struct skb_array q[PFIFO_FAST_BANDS];
714};
715
716static inline struct skb_array *band2list(struct pfifo_fast_priv *priv,
717 int band)
718{
719 return &priv->q[band];
720}
721
722static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
723 struct sk_buff **to_free)
724{
725 int band = sch_default_prio2band[skb->priority & TC_PRIO_MAX];
726 struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
727 struct skb_array *q = band2list(priv, band);
728 unsigned int pkt_len = qdisc_pkt_len(skb);
729 int err;
730
731 err = skb_array_produce(a: q, skb);
732
733 if (unlikely(err)) {
734 if (qdisc_is_percpu_stats(q: qdisc))
735 return qdisc_drop_cpu(skb, sch: qdisc, to_free);
736 else
737 return qdisc_drop(skb, sch: qdisc, to_free);
738 }
739
740 qdisc_update_stats_at_enqueue(sch: qdisc, pkt_len);
741 return NET_XMIT_SUCCESS;
742}
743
744static struct sk_buff *pfifo_fast_dequeue(struct Qdisc *qdisc)
745{
746 struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
747 struct sk_buff *skb = NULL;
748 bool need_retry = true;
749 int band;
750
751retry:
752 for (band = 0; band < PFIFO_FAST_BANDS && !skb; band++) {
753 struct skb_array *q = band2list(priv, band);
754
755 if (__skb_array_empty(a: q))
756 continue;
757
758 skb = __skb_array_consume(a: q);
759 }
760 if (likely(skb)) {
761 qdisc_update_stats_at_dequeue(sch: qdisc, skb);
762 } else if (need_retry &&
763 READ_ONCE(qdisc->state) & QDISC_STATE_NON_EMPTY) {
764 /* Delay clearing the STATE_MISSED here to reduce
765 * the overhead of the second spin_trylock() in
766 * qdisc_run_begin() and __netif_schedule() calling
767 * in qdisc_run_end().
768 */
769 clear_bit(nr: __QDISC_STATE_MISSED, addr: &qdisc->state);
770 clear_bit(nr: __QDISC_STATE_DRAINING, addr: &qdisc->state);
771
772 /* Make sure dequeuing happens after clearing
773 * STATE_MISSED.
774 */
775 smp_mb__after_atomic();
776
777 need_retry = false;
778
779 goto retry;
780 }
781
782 return skb;
783}
784
785static struct sk_buff *pfifo_fast_peek(struct Qdisc *qdisc)
786{
787 struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
788 struct sk_buff *skb = NULL;
789 int band;
790
791 for (band = 0; band < PFIFO_FAST_BANDS && !skb; band++) {
792 struct skb_array *q = band2list(priv, band);
793
794 skb = __skb_array_peek(a: q);
795 }
796
797 return skb;
798}
799
800static void pfifo_fast_reset(struct Qdisc *qdisc)
801{
802 int i, band;
803 struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
804
805 for (band = 0; band < PFIFO_FAST_BANDS; band++) {
806 struct skb_array *q = band2list(priv, band);
807 struct sk_buff *skb;
808
809 /* NULL ring is possible if destroy path is due to a failed
810 * skb_array_init() in pfifo_fast_init() case.
811 */
812 if (!q->ring.queue)
813 continue;
814
815 while ((skb = __skb_array_consume(a: q)) != NULL)
816 kfree_skb(skb);
817 }
818
819 if (qdisc_is_percpu_stats(q: qdisc)) {
820 for_each_possible_cpu(i) {
821 struct gnet_stats_queue *q;
822
823 q = per_cpu_ptr(qdisc->cpu_qstats, i);
824 q->backlog = 0;
825 q->qlen = 0;
826 }
827 }
828}
829
830static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
831{
832 struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
833
834 memcpy(&opt.priomap, sch_default_prio2band, TC_PRIO_MAX + 1);
835 if (nla_put(skb, attrtype: TCA_OPTIONS, attrlen: sizeof(opt), data: &opt))
836 goto nla_put_failure;
837 return skb->len;
838
839nla_put_failure:
840 return -1;
841}
842
843static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt,
844 struct netlink_ext_ack *extack)
845{
846 unsigned int qlen = qdisc_dev(qdisc)->tx_queue_len;
847 struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
848 int prio;
849
850 /* guard against zero length rings */
851 if (!qlen)
852 return -EINVAL;
853
854 for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
855 struct skb_array *q = band2list(priv, band: prio);
856 int err;
857
858 err = skb_array_init(a: q, size: qlen, GFP_KERNEL);
859 if (err)
860 return -ENOMEM;
861 }
862
863 /* Can by-pass the queue discipline */
864 qdisc->flags |= TCQ_F_CAN_BYPASS;
865 return 0;
866}
867
868static void pfifo_fast_destroy(struct Qdisc *sch)
869{
870 struct pfifo_fast_priv *priv = qdisc_priv(sch);
871 int prio;
872
873 for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
874 struct skb_array *q = band2list(priv, band: prio);
875
876 /* NULL ring is possible if destroy path is due to a failed
877 * skb_array_init() in pfifo_fast_init() case.
878 */
879 if (!q->ring.queue)
880 continue;
881 /* Destroy ring but no need to kfree_skb because a call to
882 * pfifo_fast_reset() has already done that work.
883 */
884 ptr_ring_cleanup(r: &q->ring, NULL);
885 }
886}
887
888static int pfifo_fast_change_tx_queue_len(struct Qdisc *sch,
889 unsigned int new_len)
890{
891 struct pfifo_fast_priv *priv = qdisc_priv(sch);
892 struct skb_array *bands[PFIFO_FAST_BANDS];
893 int prio;
894
895 for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
896 struct skb_array *q = band2list(priv, band: prio);
897
898 bands[prio] = q;
899 }
900
901 return skb_array_resize_multiple(rings: bands, PFIFO_FAST_BANDS, size: new_len,
902 GFP_KERNEL);
903}
904
905struct Qdisc_ops pfifo_fast_ops __read_mostly = {
906 .id = "pfifo_fast",
907 .priv_size = sizeof(struct pfifo_fast_priv),
908 .enqueue = pfifo_fast_enqueue,
909 .dequeue = pfifo_fast_dequeue,
910 .peek = pfifo_fast_peek,
911 .init = pfifo_fast_init,
912 .destroy = pfifo_fast_destroy,
913 .reset = pfifo_fast_reset,
914 .dump = pfifo_fast_dump,
915 .change_tx_queue_len = pfifo_fast_change_tx_queue_len,
916 .owner = THIS_MODULE,
917 .static_flags = TCQ_F_NOLOCK | TCQ_F_CPUSTATS,
918};
919EXPORT_SYMBOL(pfifo_fast_ops);
920
921static struct lock_class_key qdisc_tx_busylock;
922
923struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
924 const struct Qdisc_ops *ops,
925 struct netlink_ext_ack *extack)
926{
927 struct Qdisc *sch;
928 unsigned int size = sizeof(*sch) + ops->priv_size;
929 int err = -ENOBUFS;
930 struct net_device *dev;
931
932 if (!dev_queue) {
933 NL_SET_ERR_MSG(extack, "No device queue given");
934 err = -EINVAL;
935 goto errout;
936 }
937
938 dev = dev_queue->dev;
939 sch = kzalloc_node(size, GFP_KERNEL, node: netdev_queue_numa_node_read(q: dev_queue));
940
941 if (!sch)
942 goto errout;
943 __skb_queue_head_init(list: &sch->gso_skb);
944 __skb_queue_head_init(list: &sch->skb_bad_txq);
945 gnet_stats_basic_sync_init(b: &sch->bstats);
946 spin_lock_init(&sch->q.lock);
947
948 if (ops->static_flags & TCQ_F_CPUSTATS) {
949 sch->cpu_bstats =
950 netdev_alloc_pcpu_stats(struct gnet_stats_basic_sync);
951 if (!sch->cpu_bstats)
952 goto errout1;
953
954 sch->cpu_qstats = alloc_percpu(struct gnet_stats_queue);
955 if (!sch->cpu_qstats) {
956 free_percpu(pdata: sch->cpu_bstats);
957 goto errout1;
958 }
959 }
960
961 spin_lock_init(&sch->busylock);
962 lockdep_set_class(&sch->busylock,
963 dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
964
965 /* seqlock has the same scope of busylock, for NOLOCK qdisc */
966 spin_lock_init(&sch->seqlock);
967 lockdep_set_class(&sch->seqlock,
968 dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
969
970 sch->ops = ops;
971 sch->flags = ops->static_flags;
972 sch->enqueue = ops->enqueue;
973 sch->dequeue = ops->dequeue;
974 sch->dev_queue = dev_queue;
975 netdev_hold(dev, tracker: &sch->dev_tracker, GFP_KERNEL);
976 refcount_set(r: &sch->refcnt, n: 1);
977
978 return sch;
979errout1:
980 kfree(objp: sch);
981errout:
982 return ERR_PTR(error: err);
983}
984
985struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
986 const struct Qdisc_ops *ops,
987 unsigned int parentid,
988 struct netlink_ext_ack *extack)
989{
990 struct Qdisc *sch;
991
992 if (!try_module_get(module: ops->owner)) {
993 NL_SET_ERR_MSG(extack, "Failed to increase module reference counter");
994 return NULL;
995 }
996
997 sch = qdisc_alloc(dev_queue, ops, extack);
998 if (IS_ERR(ptr: sch)) {
999 module_put(module: ops->owner);
1000 return NULL;
1001 }
1002 sch->parent = parentid;
1003
1004 if (!ops->init || ops->init(sch, NULL, extack) == 0) {
1005 trace_qdisc_create(ops, dev: dev_queue->dev, parent: parentid);
1006 return sch;
1007 }
1008
1009 qdisc_put(qdisc: sch);
1010 return NULL;
1011}
1012EXPORT_SYMBOL(qdisc_create_dflt);
1013
1014/* Under qdisc_lock(qdisc) and BH! */
1015
1016void qdisc_reset(struct Qdisc *qdisc)
1017{
1018 const struct Qdisc_ops *ops = qdisc->ops;
1019
1020 trace_qdisc_reset(q: qdisc);
1021
1022 if (ops->reset)
1023 ops->reset(qdisc);
1024
1025 __skb_queue_purge(list: &qdisc->gso_skb);
1026 __skb_queue_purge(list: &qdisc->skb_bad_txq);
1027
1028 qdisc->q.qlen = 0;
1029 qdisc->qstats.backlog = 0;
1030}
1031EXPORT_SYMBOL(qdisc_reset);
1032
1033void qdisc_free(struct Qdisc *qdisc)
1034{
1035 if (qdisc_is_percpu_stats(q: qdisc)) {
1036 free_percpu(pdata: qdisc->cpu_bstats);
1037 free_percpu(pdata: qdisc->cpu_qstats);
1038 }
1039
1040 kfree(objp: qdisc);
1041}
1042
1043static void qdisc_free_cb(struct rcu_head *head)
1044{
1045 struct Qdisc *q = container_of(head, struct Qdisc, rcu);
1046
1047 qdisc_free(qdisc: q);
1048}
1049
1050static void __qdisc_destroy(struct Qdisc *qdisc)
1051{
1052 const struct Qdisc_ops *ops = qdisc->ops;
1053
1054#ifdef CONFIG_NET_SCHED
1055 qdisc_hash_del(q: qdisc);
1056
1057 qdisc_put_stab(rtnl_dereference(qdisc->stab));
1058#endif
1059 gen_kill_estimator(ptr: &qdisc->rate_est);
1060
1061 qdisc_reset(qdisc);
1062
1063 if (ops->destroy)
1064 ops->destroy(qdisc);
1065
1066 module_put(module: ops->owner);
1067 netdev_put(dev: qdisc_dev(qdisc), tracker: &qdisc->dev_tracker);
1068
1069 trace_qdisc_destroy(q: qdisc);
1070
1071 call_rcu(head: &qdisc->rcu, func: qdisc_free_cb);
1072}
1073
1074void qdisc_destroy(struct Qdisc *qdisc)
1075{
1076 if (qdisc->flags & TCQ_F_BUILTIN)
1077 return;
1078
1079 __qdisc_destroy(qdisc);
1080}
1081
1082void qdisc_put(struct Qdisc *qdisc)
1083{
1084 if (!qdisc)
1085 return;
1086
1087 if (qdisc->flags & TCQ_F_BUILTIN ||
1088 !refcount_dec_and_test(r: &qdisc->refcnt))
1089 return;
1090
1091 __qdisc_destroy(qdisc);
1092}
1093EXPORT_SYMBOL(qdisc_put);
1094
1095/* Version of qdisc_put() that is called with rtnl mutex unlocked.
1096 * Intended to be used as optimization, this function only takes rtnl lock if
1097 * qdisc reference counter reached zero.
1098 */
1099
1100void qdisc_put_unlocked(struct Qdisc *qdisc)
1101{
1102 if (qdisc->flags & TCQ_F_BUILTIN ||
1103 !refcount_dec_and_rtnl_lock(r: &qdisc->refcnt))
1104 return;
1105
1106 __qdisc_destroy(qdisc);
1107 rtnl_unlock();
1108}
1109EXPORT_SYMBOL(qdisc_put_unlocked);
1110
1111/* Attach toplevel qdisc to device queue. */
1112struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
1113 struct Qdisc *qdisc)
1114{
1115 struct Qdisc *oqdisc = rtnl_dereference(dev_queue->qdisc_sleeping);
1116 spinlock_t *root_lock;
1117
1118 root_lock = qdisc_lock(qdisc: oqdisc);
1119 spin_lock_bh(lock: root_lock);
1120
1121 /* ... and graft new one */
1122 if (qdisc == NULL)
1123 qdisc = &noop_qdisc;
1124 rcu_assign_pointer(dev_queue->qdisc_sleeping, qdisc);
1125 rcu_assign_pointer(dev_queue->qdisc, &noop_qdisc);
1126
1127 spin_unlock_bh(lock: root_lock);
1128
1129 return oqdisc;
1130}
1131EXPORT_SYMBOL(dev_graft_qdisc);
1132
1133static void shutdown_scheduler_queue(struct net_device *dev,
1134 struct netdev_queue *dev_queue,
1135 void *_qdisc_default)
1136{
1137 struct Qdisc *qdisc = rtnl_dereference(dev_queue->qdisc_sleeping);
1138 struct Qdisc *qdisc_default = _qdisc_default;
1139
1140 if (qdisc) {
1141 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
1142 rcu_assign_pointer(dev_queue->qdisc_sleeping, qdisc_default);
1143
1144 qdisc_put(qdisc);
1145 }
1146}
1147
1148static void attach_one_default_qdisc(struct net_device *dev,
1149 struct netdev_queue *dev_queue,
1150 void *_unused)
1151{
1152 struct Qdisc *qdisc;
1153 const struct Qdisc_ops *ops = default_qdisc_ops;
1154
1155 if (dev->priv_flags & IFF_NO_QUEUE)
1156 ops = &noqueue_qdisc_ops;
1157 else if(dev->type == ARPHRD_CAN)
1158 ops = &pfifo_fast_ops;
1159
1160 qdisc = qdisc_create_dflt(dev_queue, ops, TC_H_ROOT, NULL);
1161 if (!qdisc)
1162 return;
1163
1164 if (!netif_is_multiqueue(dev))
1165 qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
1166 rcu_assign_pointer(dev_queue->qdisc_sleeping, qdisc);
1167}
1168
1169static void attach_default_qdiscs(struct net_device *dev)
1170{
1171 struct netdev_queue *txq;
1172 struct Qdisc *qdisc;
1173
1174 txq = netdev_get_tx_queue(dev, index: 0);
1175
1176 if (!netif_is_multiqueue(dev) ||
1177 dev->priv_flags & IFF_NO_QUEUE) {
1178 netdev_for_each_tx_queue(dev, f: attach_one_default_qdisc, NULL);
1179 qdisc = rtnl_dereference(txq->qdisc_sleeping);
1180 rcu_assign_pointer(dev->qdisc, qdisc);
1181 qdisc_refcount_inc(qdisc);
1182 } else {
1183 qdisc = qdisc_create_dflt(txq, &mq_qdisc_ops, TC_H_ROOT, NULL);
1184 if (qdisc) {
1185 rcu_assign_pointer(dev->qdisc, qdisc);
1186 qdisc->ops->attach(qdisc);
1187 }
1188 }
1189 qdisc = rtnl_dereference(dev->qdisc);
1190
1191 /* Detect default qdisc setup/init failed and fallback to "noqueue" */
1192 if (qdisc == &noop_qdisc) {
1193 netdev_warn(dev, format: "default qdisc (%s) fail, fallback to %s\n",
1194 default_qdisc_ops->id, noqueue_qdisc_ops.id);
1195 netdev_for_each_tx_queue(dev, f: shutdown_scheduler_queue, arg: &noop_qdisc);
1196 dev->priv_flags |= IFF_NO_QUEUE;
1197 netdev_for_each_tx_queue(dev, f: attach_one_default_qdisc, NULL);
1198 qdisc = rtnl_dereference(txq->qdisc_sleeping);
1199 rcu_assign_pointer(dev->qdisc, qdisc);
1200 qdisc_refcount_inc(qdisc);
1201 dev->priv_flags ^= IFF_NO_QUEUE;
1202 }
1203
1204#ifdef CONFIG_NET_SCHED
1205 if (qdisc != &noop_qdisc)
1206 qdisc_hash_add(q: qdisc, invisible: false);
1207#endif
1208}
1209
1210static void transition_one_qdisc(struct net_device *dev,
1211 struct netdev_queue *dev_queue,
1212 void *_need_watchdog)
1213{
1214 struct Qdisc *new_qdisc = rtnl_dereference(dev_queue->qdisc_sleeping);
1215 int *need_watchdog_p = _need_watchdog;
1216
1217 if (!(new_qdisc->flags & TCQ_F_BUILTIN))
1218 clear_bit(nr: __QDISC_STATE_DEACTIVATED, addr: &new_qdisc->state);
1219
1220 rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
1221 if (need_watchdog_p) {
1222 WRITE_ONCE(dev_queue->trans_start, 0);
1223 *need_watchdog_p = 1;
1224 }
1225}
1226
1227void dev_activate(struct net_device *dev)
1228{
1229 int need_watchdog;
1230
1231 /* No queueing discipline is attached to device;
1232 * create default one for devices, which need queueing
1233 * and noqueue_qdisc for virtual interfaces
1234 */
1235
1236 if (rtnl_dereference(dev->qdisc) == &noop_qdisc)
1237 attach_default_qdiscs(dev);
1238
1239 if (!netif_carrier_ok(dev))
1240 /* Delay activation until next carrier-on event */
1241 return;
1242
1243 need_watchdog = 0;
1244 netdev_for_each_tx_queue(dev, f: transition_one_qdisc, arg: &need_watchdog);
1245 if (dev_ingress_queue(dev))
1246 transition_one_qdisc(dev, dev_queue: dev_ingress_queue(dev), NULL);
1247
1248 if (need_watchdog) {
1249 netif_trans_update(dev);
1250 dev_watchdog_up(dev);
1251 }
1252}
1253EXPORT_SYMBOL(dev_activate);
1254
1255static void qdisc_deactivate(struct Qdisc *qdisc)
1256{
1257 if (qdisc->flags & TCQ_F_BUILTIN)
1258 return;
1259
1260 set_bit(nr: __QDISC_STATE_DEACTIVATED, addr: &qdisc->state);
1261}
1262
1263static void dev_deactivate_queue(struct net_device *dev,
1264 struct netdev_queue *dev_queue,
1265 void *_qdisc_default)
1266{
1267 struct Qdisc *qdisc_default = _qdisc_default;
1268 struct Qdisc *qdisc;
1269
1270 qdisc = rtnl_dereference(dev_queue->qdisc);
1271 if (qdisc) {
1272 qdisc_deactivate(qdisc);
1273 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
1274 }
1275}
1276
1277static void dev_reset_queue(struct net_device *dev,
1278 struct netdev_queue *dev_queue,
1279 void *_unused)
1280{
1281 struct Qdisc *qdisc;
1282 bool nolock;
1283
1284 qdisc = rtnl_dereference(dev_queue->qdisc_sleeping);
1285 if (!qdisc)
1286 return;
1287
1288 nolock = qdisc->flags & TCQ_F_NOLOCK;
1289
1290 if (nolock)
1291 spin_lock_bh(lock: &qdisc->seqlock);
1292 spin_lock_bh(lock: qdisc_lock(qdisc));
1293
1294 qdisc_reset(qdisc);
1295
1296 spin_unlock_bh(lock: qdisc_lock(qdisc));
1297 if (nolock) {
1298 clear_bit(nr: __QDISC_STATE_MISSED, addr: &qdisc->state);
1299 clear_bit(nr: __QDISC_STATE_DRAINING, addr: &qdisc->state);
1300 spin_unlock_bh(lock: &qdisc->seqlock);
1301 }
1302}
1303
1304static bool some_qdisc_is_busy(struct net_device *dev)
1305{
1306 unsigned int i;
1307
1308 for (i = 0; i < dev->num_tx_queues; i++) {
1309 struct netdev_queue *dev_queue;
1310 spinlock_t *root_lock;
1311 struct Qdisc *q;
1312 int val;
1313
1314 dev_queue = netdev_get_tx_queue(dev, index: i);
1315 q = rtnl_dereference(dev_queue->qdisc_sleeping);
1316
1317 root_lock = qdisc_lock(qdisc: q);
1318 spin_lock_bh(lock: root_lock);
1319
1320 val = (qdisc_is_running(qdisc: q) ||
1321 test_bit(__QDISC_STATE_SCHED, &q->state));
1322
1323 spin_unlock_bh(lock: root_lock);
1324
1325 if (val)
1326 return true;
1327 }
1328 return false;
1329}
1330
1331/**
1332 * dev_deactivate_many - deactivate transmissions on several devices
1333 * @head: list of devices to deactivate
1334 *
1335 * This function returns only when all outstanding transmissions
1336 * have completed, unless all devices are in dismantle phase.
1337 */
1338void dev_deactivate_many(struct list_head *head)
1339{
1340 struct net_device *dev;
1341
1342 list_for_each_entry(dev, head, close_list) {
1343 netdev_for_each_tx_queue(dev, f: dev_deactivate_queue,
1344 arg: &noop_qdisc);
1345 if (dev_ingress_queue(dev))
1346 dev_deactivate_queue(dev, dev_queue: dev_ingress_queue(dev),
1347 qdisc_default: &noop_qdisc);
1348
1349 dev_watchdog_down(dev);
1350 }
1351
1352 /* Wait for outstanding qdisc-less dev_queue_xmit calls or
1353 * outstanding qdisc enqueuing calls.
1354 * This is avoided if all devices are in dismantle phase :
1355 * Caller will call synchronize_net() for us
1356 */
1357 synchronize_net();
1358
1359 list_for_each_entry(dev, head, close_list) {
1360 netdev_for_each_tx_queue(dev, f: dev_reset_queue, NULL);
1361
1362 if (dev_ingress_queue(dev))
1363 dev_reset_queue(dev, dev_queue: dev_ingress_queue(dev), NULL);
1364 }
1365
1366 /* Wait for outstanding qdisc_run calls. */
1367 list_for_each_entry(dev, head, close_list) {
1368 while (some_qdisc_is_busy(dev)) {
1369 /* wait_event() would avoid this sleep-loop but would
1370 * require expensive checks in the fast paths of packet
1371 * processing which isn't worth it.
1372 */
1373 schedule_timeout_uninterruptible(timeout: 1);
1374 }
1375 }
1376}
1377
1378void dev_deactivate(struct net_device *dev)
1379{
1380 LIST_HEAD(single);
1381
1382 list_add(new: &dev->close_list, head: &single);
1383 dev_deactivate_many(head: &single);
1384 list_del(entry: &single);
1385}
1386EXPORT_SYMBOL(dev_deactivate);
1387
1388static int qdisc_change_tx_queue_len(struct net_device *dev,
1389 struct netdev_queue *dev_queue)
1390{
1391 struct Qdisc *qdisc = rtnl_dereference(dev_queue->qdisc_sleeping);
1392 const struct Qdisc_ops *ops = qdisc->ops;
1393
1394 if (ops->change_tx_queue_len)
1395 return ops->change_tx_queue_len(qdisc, dev->tx_queue_len);
1396 return 0;
1397}
1398
1399void dev_qdisc_change_real_num_tx(struct net_device *dev,
1400 unsigned int new_real_tx)
1401{
1402 struct Qdisc *qdisc = rtnl_dereference(dev->qdisc);
1403
1404 if (qdisc->ops->change_real_num_tx)
1405 qdisc->ops->change_real_num_tx(qdisc, new_real_tx);
1406}
1407
1408void mq_change_real_num_tx(struct Qdisc *sch, unsigned int new_real_tx)
1409{
1410#ifdef CONFIG_NET_SCHED
1411 struct net_device *dev = qdisc_dev(qdisc: sch);
1412 struct Qdisc *qdisc;
1413 unsigned int i;
1414
1415 for (i = new_real_tx; i < dev->real_num_tx_queues; i++) {
1416 qdisc = rtnl_dereference(netdev_get_tx_queue(dev, i)->qdisc_sleeping);
1417 /* Only update the default qdiscs we created,
1418 * qdiscs with handles are always hashed.
1419 */
1420 if (qdisc != &noop_qdisc && !qdisc->handle)
1421 qdisc_hash_del(q: qdisc);
1422 }
1423 for (i = dev->real_num_tx_queues; i < new_real_tx; i++) {
1424 qdisc = rtnl_dereference(netdev_get_tx_queue(dev, i)->qdisc_sleeping);
1425 if (qdisc != &noop_qdisc && !qdisc->handle)
1426 qdisc_hash_add(q: qdisc, invisible: false);
1427 }
1428#endif
1429}
1430EXPORT_SYMBOL(mq_change_real_num_tx);
1431
1432int dev_qdisc_change_tx_queue_len(struct net_device *dev)
1433{
1434 bool up = dev->flags & IFF_UP;
1435 unsigned int i;
1436 int ret = 0;
1437
1438 if (up)
1439 dev_deactivate(dev);
1440
1441 for (i = 0; i < dev->num_tx_queues; i++) {
1442 ret = qdisc_change_tx_queue_len(dev, dev_queue: &dev->_tx[i]);
1443
1444 /* TODO: revert changes on a partial failure */
1445 if (ret)
1446 break;
1447 }
1448
1449 if (up)
1450 dev_activate(dev);
1451 return ret;
1452}
1453
1454static void dev_init_scheduler_queue(struct net_device *dev,
1455 struct netdev_queue *dev_queue,
1456 void *_qdisc)
1457{
1458 struct Qdisc *qdisc = _qdisc;
1459
1460 rcu_assign_pointer(dev_queue->qdisc, qdisc);
1461 rcu_assign_pointer(dev_queue->qdisc_sleeping, qdisc);
1462}
1463
1464void dev_init_scheduler(struct net_device *dev)
1465{
1466 rcu_assign_pointer(dev->qdisc, &noop_qdisc);
1467 netdev_for_each_tx_queue(dev, f: dev_init_scheduler_queue, arg: &noop_qdisc);
1468 if (dev_ingress_queue(dev))
1469 dev_init_scheduler_queue(dev, dev_queue: dev_ingress_queue(dev), qdisc: &noop_qdisc);
1470
1471 timer_setup(&dev->watchdog_timer, dev_watchdog, 0);
1472}
1473
1474void dev_shutdown(struct net_device *dev)
1475{
1476 netdev_for_each_tx_queue(dev, f: shutdown_scheduler_queue, arg: &noop_qdisc);
1477 if (dev_ingress_queue(dev))
1478 shutdown_scheduler_queue(dev, dev_queue: dev_ingress_queue(dev), qdisc_default: &noop_qdisc);
1479 qdisc_put(rtnl_dereference(dev->qdisc));
1480 rcu_assign_pointer(dev->qdisc, &noop_qdisc);
1481
1482 WARN_ON(timer_pending(&dev->watchdog_timer));
1483}
1484
1485/**
1486 * psched_ratecfg_precompute__() - Pre-compute values for reciprocal division
1487 * @rate: Rate to compute reciprocal division values of
1488 * @mult: Multiplier for reciprocal division
1489 * @shift: Shift for reciprocal division
1490 *
1491 * The multiplier and shift for reciprocal division by rate are stored
1492 * in mult and shift.
1493 *
1494 * The deal here is to replace a divide by a reciprocal one
1495 * in fast path (a reciprocal divide is a multiply and a shift)
1496 *
1497 * Normal formula would be :
1498 * time_in_ns = (NSEC_PER_SEC * len) / rate_bps
1499 *
1500 * We compute mult/shift to use instead :
1501 * time_in_ns = (len * mult) >> shift;
1502 *
1503 * We try to get the highest possible mult value for accuracy,
1504 * but have to make sure no overflows will ever happen.
1505 *
1506 * reciprocal_value() is not used here it doesn't handle 64-bit values.
1507 */
1508static void psched_ratecfg_precompute__(u64 rate, u32 *mult, u8 *shift)
1509{
1510 u64 factor = NSEC_PER_SEC;
1511
1512 *mult = 1;
1513 *shift = 0;
1514
1515 if (rate <= 0)
1516 return;
1517
1518 for (;;) {
1519 *mult = div64_u64(dividend: factor, divisor: rate);
1520 if (*mult & (1U << 31) || factor & (1ULL << 63))
1521 break;
1522 factor <<= 1;
1523 (*shift)++;
1524 }
1525}
1526
1527void psched_ratecfg_precompute(struct psched_ratecfg *r,
1528 const struct tc_ratespec *conf,
1529 u64 rate64)
1530{
1531 memset(r, 0, sizeof(*r));
1532 r->overhead = conf->overhead;
1533 r->mpu = conf->mpu;
1534 r->rate_bytes_ps = max_t(u64, conf->rate, rate64);
1535 r->linklayer = (conf->linklayer & TC_LINKLAYER_MASK);
1536 psched_ratecfg_precompute__(rate: r->rate_bytes_ps, mult: &r->mult, shift: &r->shift);
1537}
1538EXPORT_SYMBOL(psched_ratecfg_precompute);
1539
1540void psched_ppscfg_precompute(struct psched_pktrate *r, u64 pktrate64)
1541{
1542 r->rate_pkts_ps = pktrate64;
1543 psched_ratecfg_precompute__(rate: r->rate_pkts_ps, mult: &r->mult, shift: &r->shift);
1544}
1545EXPORT_SYMBOL(psched_ppscfg_precompute);
1546
1547void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp,
1548 struct tcf_proto *tp_head)
1549{
1550 /* Protected with chain0->filter_chain_lock.
1551 * Can't access chain directly because tp_head can be NULL.
1552 */
1553 struct mini_Qdisc *miniq_old =
1554 rcu_dereference_protected(*miniqp->p_miniq, 1);
1555 struct mini_Qdisc *miniq;
1556
1557 if (!tp_head) {
1558 RCU_INIT_POINTER(*miniqp->p_miniq, NULL);
1559 } else {
1560 miniq = miniq_old != &miniqp->miniq1 ?
1561 &miniqp->miniq1 : &miniqp->miniq2;
1562
1563 /* We need to make sure that readers won't see the miniq
1564 * we are about to modify. So ensure that at least one RCU
1565 * grace period has elapsed since the miniq was made
1566 * inactive.
1567 */
1568 if (IS_ENABLED(CONFIG_PREEMPT_RT))
1569 cond_synchronize_rcu(oldstate: miniq->rcu_state);
1570 else if (!poll_state_synchronize_rcu(oldstate: miniq->rcu_state))
1571 synchronize_rcu_expedited();
1572
1573 miniq->filter_list = tp_head;
1574 rcu_assign_pointer(*miniqp->p_miniq, miniq);
1575 }
1576
1577 if (miniq_old)
1578 /* This is counterpart of the rcu sync above. We need to
1579 * block potential new user of miniq_old until all readers
1580 * are not seeing it.
1581 */
1582 miniq_old->rcu_state = start_poll_synchronize_rcu();
1583}
1584EXPORT_SYMBOL(mini_qdisc_pair_swap);
1585
1586void mini_qdisc_pair_block_init(struct mini_Qdisc_pair *miniqp,
1587 struct tcf_block *block)
1588{
1589 miniqp->miniq1.block = block;
1590 miniqp->miniq2.block = block;
1591}
1592EXPORT_SYMBOL(mini_qdisc_pair_block_init);
1593
1594void mini_qdisc_pair_init(struct mini_Qdisc_pair *miniqp, struct Qdisc *qdisc,
1595 struct mini_Qdisc __rcu **p_miniq)
1596{
1597 miniqp->miniq1.cpu_bstats = qdisc->cpu_bstats;
1598 miniqp->miniq1.cpu_qstats = qdisc->cpu_qstats;
1599 miniqp->miniq2.cpu_bstats = qdisc->cpu_bstats;
1600 miniqp->miniq2.cpu_qstats = qdisc->cpu_qstats;
1601 miniqp->miniq1.rcu_state = get_state_synchronize_rcu();
1602 miniqp->miniq2.rcu_state = miniqp->miniq1.rcu_state;
1603 miniqp->p_miniq = p_miniq;
1604}
1605EXPORT_SYMBOL(mini_qdisc_pair_init);
1606

source code of linux/net/sched/sch_generic.c