summaryrefslogtreecommitdiffstats
path: root/net/sched/sch_generic.c
blob: 99b697ad2b983a929d8a194411ff013f2824c122 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * net/sched/sch_generic.c	Generic packet scheduler routines.
 *
 * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
 *              Jamal Hadi Salim, <hadi@cyberus.ca> 990601
 *              - Ingress support
 */

#include <linux/bitops.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <linux/init.h>
#include <linux/rcupdate.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/if_vlan.h>
#include <linux/skb_array.h>
#include <linux/if_macvlan.h>
#include <net/sch_generic.h>
#include <net/pkt_sched.h>
#include <net/dst.h>
#include <trace/events/qdisc.h>
#include <trace/events/net.h>
#include <net/xfrm.h>

/* Qdisc to use by default */
const struct Qdisc_ops *default_qdisc_ops = &pfifo_fast_ops;
EXPORT_SYMBOL(default_qdisc_ops);

static void qdisc_maybe_clear_missed(struct Qdisc *q,
				     const struct netdev_queue *txq)
{
	clear_bit(__QDISC_STATE_MISSED, &q->state);

	/* Make sure the below netif_xmit_frozen_or_stopped()
	 * checking happens after clearing STATE_MISSED.
	 */
	smp_mb__after_atomic();

	/* Checking netif_xmit_frozen_or_stopped() again to
	 * make sure STATE_MISSED is set if the STATE_MISSED
	 * set by netif_tx_wake_queue()'s rescheduling of
	 * net_tx_action() is cleared by the above clear_bit().
	 */
	if (!netif_xmit_frozen_or_stopped(txq))
		set_bit(__QDISC_STATE_MISSED, &q->state);
	else
		set_bit(__QDISC_STATE_DRAINING, &q->state);
}

/* Main transmission queue. */

/* Modifications to data participating in scheduling must be protected with
 * qdisc_lock(qdisc) spinlock.
 *
 * The idea is the following:
 * - enqueue, dequeue are serialized via qdisc root lock
 * - ingress filtering is also serialized via qdisc root lock
 * - updates to tree and tree walking are only done under the rtnl mutex.
 */

#define SKB_XOFF_MAGIC ((struct sk_buff *)1UL)

static inline struct sk_buff *__skb_dequeue_bad_txq(struct Qdisc *q)
{
	const struct netdev_queue *txq = q->dev_queue;
	spinlock_t *lock = NULL;
	struct sk_buff *skb;

	if (q->flags & TCQ_F_NOLOCK) {
		lock = qdisc_lock(q);
		spin_lock(lock);
	}

	skb = skb_peek(&q->skb_bad_txq);
	if (skb) {
		/* check the reason of requeuing without tx lock first */
		txq = skb_get_tx_queue(txq->dev, skb);
		if (!netif_xmit_frozen_or_stopped(txq)) {
			skb = __skb_dequeue(&q->skb_bad_txq);
			if (qdisc_is_percpu_stats(q)) {
				qdisc_qstats_cpu_backlog_dec(q, skb);
				qdisc_qstats_cpu_qlen_dec(q);
			} else {
				qdisc_qstats_backlog_dec(q, skb);
				q->q.qlen--;
			}
		} else {
			skb = SKB_XOFF_MAGIC;
			qdisc_maybe_clear_missed(q, txq);
		}
	}

	if (lock)
		spin_unlock(lock);

	return skb;
}

static inline struct sk_buff *qdisc_dequeue_skb_bad_txq(struct Qdisc *q)
{
	struct sk_buff *skb = skb_peek(&q->skb_bad_txq);

	if (unlikely(skb))
		skb = __skb_dequeue_bad_txq(q);

	return skb;
}

static inline void qdisc_enqueue_skb_bad_txq(struct Qdisc *q,
					     struct sk_buff *skb)
{
	spinlock_t *lock = NULL;

	if (q->flags & TCQ_F_NOLOCK) {
		lock = qdisc_lock(q);
		spin_lock(lock);
	}

	__skb_queue_tail(&q->skb_bad_txq, skb);

	if (qdisc_is_percpu_stats(q)) {
		qdisc_qstats_cpu_backlog_inc(q, skb);
		qdisc_qstats_cpu_qlen_inc(q);
	} else {
		qdisc_qstats_backlog_inc(q, skb);
		q->q.qlen++;
	}

	if (lock)
		spin_unlock(lock);
}

static inline void dev_requeue_skb(struct sk_buff *skb, struct Qdisc *q)
{
	spinlock_t *lock = NULL;

	if (q->flags & TCQ_F_NOLOCK) {
		lock = qdisc_lock(q);
		spin_lock(lock);
	}

	while (skb) {
		struct sk_buff *next = skb->next;

		__skb_queue_tail(&q->gso_skb, skb);

		/* it's still part of the queue */
		if (qdisc_is_percpu_stats(q)) {
			qdisc_qstats_cpu_requeues_inc(q);
			qdisc_qstats_cpu_backlog_inc(q, skb);
			qdisc_qstats_cpu_qlen_inc(q);
		} else {
			q->qstats.requeues++;
			qdisc_qstats_backlog_inc(q, skb);
			q->q.qlen++;
		}

		skb = next;
	}

	if (lock) {
		spin_unlock(lock);
		set_bit(__QDISC_STATE_MISSED, &q->state);
	} else {
		__netif_schedule(q);
	}
}

static void try_bulk_dequeue_skb(struct Qdisc *q,
				 struct sk_buff *skb,
				 const struct netdev_queue *txq,
				 int *packets)
{
	int bytelimit = qdisc_avail_bulklimit(txq) - skb->len;

	while (bytelimit > 0) {
		struct sk_buff *nskb = q->dequeue(q);

		if (!nskb)
			break;

		bytelimit -= nskb->len; /* covers GSO len */
		skb->next = nskb;
		skb = nskb;
		(*packets)++; /* GSO counts as one pkt */
	}
	skb_mark_not_on_list(skb);
}

/* This variant of try_bulk_dequeue_skb() makes sure
 * all skbs in the chain are for the same txq
 */
static void try_bulk_dequeue_skb_slow(struct Qdisc *q,
				      struct sk_buff *skb,
				      int *packets)
{
	int mapping = skb_get_queue_mapping(skb);
	struct sk_buff *nskb;
	int cnt = 0;

	do {
		nskb = q->dequeue(q);
		if (!nskb)
			break;
		if (unlikely(skb_get_queue_mapping(nskb) != mapping)) {
			qdisc_enqueue_skb_bad_txq(q, nskb);
			break;
		}
		skb->next = nskb;
		skb = nskb;
	} while (++cnt < 8);
	(*packets) += cnt;
	skb_mark_not_on_list(skb);
}

/* Note that dequeue_skb can possibly return a SKB list (via skb->next).
 * A requeued skb (via q->gso_skb) can also be a SKB list.
 */
static struct sk_buff *dequeue_skb(struct Qdisc *q, bool *validate,
				   int *packets)
{
	const struct netdev_queue *txq = q->dev_queue;
	struct sk_buff *skb = NULL;

	*packets = 1;
	if (unlikely(!skb_queue_empty(&q->gso_skb))) {
		spinlock_t *lock = NULL;

		if (q->flags & TCQ_F_NOLOCK) {
			lock = qdisc_lock(q);
			spin_lock(lock);
		}

		skb = skb_peek(&q->gso_skb);

		/* skb may be null if another cpu pulls gso_skb off in between
		 * empty check and lock.
		 */
		if (!skb) {
			if (lock)
				spin_unlock(lock);
			goto validate;
		}

		/* skb in gso_skb were already validated */
		*validate = false;
		if (xfrm_offload(skb))
			*validate = true;
		/* check the reason of requeuing without tx lock first */
		txq = skb_get_tx_queue(txq->dev, skb);
		if (!netif_xmit_frozen_or_stopped(txq)) {
			skb = __skb_dequeue(&q->gso_skb);
			if (qdisc_is_percpu_stats(q)) {
				qdisc_qstats_cpu_backlog_dec(q, skb);
				qdisc_qstats_cpu_qlen_dec(q);
			} else {
				qdisc_qstats_backlog_dec(q, skb);
				q->q.qlen--;
			}
		} else {
			skb = NULL;
			qdisc_maybe_clear_missed(q, txq);
		}
		if (lock)
			spin_unlock(lock);
		goto trace;
	}
validate:
	*validate = true;

	if ((q->flags & TCQ_F_ONETXQUEUE) &&
	    netif_xmit_frozen_or_stopped(txq)) {
		qdisc_maybe_clear_missed(q, txq);
		return skb;
	}

	skb = qdisc_dequeue_skb_bad_txq(q);
	if (unlikely(skb)) {
		if (skb == SKB_XOFF_MAGIC)
			return NULL;
		goto bulk;
	}
	skb = q->dequeue(q);
	if (skb) {
bulk:
		if (qdisc_may_bulk(q))
			try_bulk_dequeue_skb(q, skb, txq, packets);
		else
			try_bulk_dequeue_skb_slow(q, skb, packets);
	}
trace:
	trace_qdisc_dequeue(q, txq, *packets, skb);
	return skb;
}

/*
 * Transmit possibly several skbs, and handle the return status as
 * required. Owning qdisc running bit guarantees that only one CPU
 * can execute this function.
 *
 * Returns to the caller:
 *				false  - hardware queue frozen backoff
 *				true   - feel free to send more pkts
 */
bool sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
		     struct net_device *dev, struct netdev_queue *txq,
		     spinlock_t *root_lock, bool validate)
{
	int ret = NETDEV_TX_BUSY;
	bool again = false;

	/* And release qdisc */
	if (root_lock)
		spin_unlock(root_lock);

	/* Note that we validate skb (GSO, checksum, ...) outside of locks */
	if (validate)
		skb = validate_xmit_skb_list(skb, dev, &again);

#ifdef CONFIG_XFRM_OFFLOAD
	if (unlikely(again)) {
		if (root_lock)
			spin_lock(root_lock);

		dev_requeue_skb(skb, q);
		return false;
	}
#endif

	if (likely(skb)) {
		HARD_TX_LOCK(dev, txq, smp_processor_id());
		if (!netif_xmit_frozen_or_stopped(txq))
			skb = dev_hard_start_xmit(skb, dev, txq, &ret);
		else
			qdisc_maybe_clear_missed(q, txq);

		HARD_TX_UNLOCK(dev, txq);
	} else {
		if (root_lock)
			spin_lock(root_lock);
		return true;
	}

	if (root_lock)
		spin_lock(root_lock);

	if (!dev_xmit_complete(ret)) {
		/* Driver returned NETDEV_TX_BUSY - requeue skb */
		if (unlikely(ret != NETDEV_TX_BUSY))
			net_warn_ratelimited("BUG %s code %d qlen %d\n",
					     dev->name, ret, q->q.qlen);

		dev_requeue_skb(skb, q);
		return false;
	}

	return true;
}

/*
 * NOTE: Called under qdisc_lock(q) with locally disabled BH.
 *
 * running seqcount guarantees only one CPU can process
 * this qdisc at a time. qdisc_lock(q) serializes queue accesses for
 * this queue.
 *
 *  netif_tx_lock serializes accesses to device driver.
 *
 *  qdisc_lock(q) and netif_tx_lock are mutually exclusive,
 *  if one is grabbed, another must be free.
 *
 * Note, that this procedure can be called by a watchdog timer
 *
 * Returns to the caller:
 *				0  - queue is empty or throttled.
 *				>0 - queue is not empty.
 *
 */
static inline bool qdisc_restart(struct Qdisc *q, int *packets)
{
	spinlock_t *root_lock = NULL;
	struct netdev_queue *txq;
	struct net_device *dev;
	struct sk_buff *skb;
	bool validate;

	/* Dequeue packet */
	skb = dequeue_skb(q, &validate, packets);
	if (unlikely(!skb))
		return false;

	if (!(q->flags & TCQ_F_NOLOCK))
		root_lock = qdisc_lock(q);

	dev = qdisc_dev(q);
	txq = skb_get_tx_queue(dev, skb);

	return sch_direct_xmit(skb, q, dev, txq, root_lock, validate);
}

void __qdisc_run(struct Qdisc *q)
{
	int quota = READ_ONCE(dev_tx_weight);
	int packets;

	while (qdisc_restart(q, &packets)) {
		quota -= packets;
		if (quota <= 0) {
			if (q->flags & TCQ_F_NOLOCK)
				set_bit(__QDISC_STATE_MISSED, &q->state);
			else
				__netif_schedule(q);

			break;
		}
	}
}

unsigned long dev_trans_start(struct net_device *dev)
{
	unsigned long res = READ_ONCE(netdev_get_tx_queue(dev, 0)->trans_start);
	unsigned long val;
	unsigned int i;

	for (i = 1; i < dev->num_tx_queues; i++) {
		val = READ_ONCE(netdev_get_tx_queue(dev, i)->trans_start);
		if (val && time_after(val, res))
			res = val;
	}

	return res;
}
EXPORT_SYMBOL(dev_trans_start);

static void netif_freeze_queues(struct net_device *dev)
{
	unsigned int i;
	int cpu;

	cpu = smp_processor_id();
	for (i = 0; i < dev->num_tx_queues; i++) {
		struct netdev_queue *txq = netdev_get_tx_queue(dev, i);

		/* We are the only thread of execution doing a
		 * freeze, but we have to grab the _xmit_lock in
		 * order to synchronize with threads which are in
		 * the ->hard_start_xmit() handler and already
		 * checked the frozen bit.
		 */
		__netif_tx_lock(txq, cpu);
		set_bit(__QUEUE_STATE_FROZEN, &txq->state);
		__netif_tx_unlock(txq);
	}
}

void netif_tx_lock(struct net_device *dev)
{
	spin_lock(&dev->tx_global_lock);
	netif_freeze_queues(dev);
}
EXPORT_SYMBOL(netif_tx_lock);

static void netif_unfreeze_queues(struct net_device *dev)
{
	unsigned int i;

	for (i = 0; i < dev->num_tx_queues; i++) {
		struct netdev_queue *txq = netdev_get_tx_queue(dev, i);

		/* No need to grab the _xmit_lock here.  If the
		 * queue is not stopped for another reason, we
		 * force a schedule.
		 */
		clear_bit(__QUEUE_STATE_FROZEN, &txq->state);
		netif_schedule_queue(txq);
	}
}

void netif_tx_unlock(struct net_device *dev)
{
	netif_unfreeze_queues(dev);
	spin_unlock(&dev->tx_global_lock);
}
EXPORT_SYMBOL(netif_tx_unlock);

static void dev_watchdog(struct timer_list *t)
{
	struct net_device *dev = from_timer(dev, t, watchdog_timer);
	bool release = true;

	spin_lock(&dev->tx_global_lock);
	if (!qdisc_tx_is_noop(dev)) {
		if (netif_device_present(dev) &&
		    netif_running(dev) &&
		    netif_carrier_ok(dev)) {
			int some_queue_timedout = 0;
			unsigned int i;
			unsigned long trans_start;

			for (i = 0; i < dev->num_tx_queues; i++) {
				struct netdev_queue *txq;

				txq = netdev_get_tx_queue(dev, i);
				trans_start = READ_ONCE(txq->trans_start);
				if (netif_xmit_stopped(txq) &&
				    time_after(jiffies, (trans_start +
							 dev->watchdog_timeo))) {
					some_queue_timedout = 1;
					atomic_long_inc(&txq->trans_timeout);
					break;
				}
			}

			if (unlikely(some_queue_timedout)) {
				trace_net_dev_xmit_timeout(dev, i);
				WARN_ONCE(1, KERN_INFO "NETDEV WATCHDOG: %s (%s): transmit queue %u timed out\n",
				       dev->name, netdev_drivername(dev), i);
				netif_freeze_queues(dev);
				dev->netdev_ops->ndo_tx_timeout(dev, i);
				netif_unfreeze_queues(dev);
			}
			if (!mod_timer(&dev->watchdog_timer,
				       round_jiffies(jiffies +
						     dev->watchdog_timeo)))
				release = false;
		}
	}
	spin_unlock(&dev->tx_global_lock);

	if (release)
		netdev_put(dev, &dev->watchdog_dev_tracker);
}

void __netdev_watchdog_up(struct net_device *dev)
{
	if (dev->netdev_ops->ndo_tx_timeout) {
		if (dev->watchdog_timeo <= 0)
			dev->watchdog_timeo = 5*HZ;
		if (!mod_timer(&dev->watchdog_timer,
			       round_jiffies(jiffies + dev->watchdog_timeo)))
			netdev_hold(dev, &dev->watchdog_dev_tracker,
				    GFP_ATOMIC);
	}
}
EXPORT_SYMBOL_GPL(__netdev_watchdog_up);

static void dev_watchdog_up(struct net_device *dev)
{
	__netdev_watchdog_up(dev);
}

static void dev_watchdog_down(struct net_device *dev)
{
	netif_tx_lock_bh(dev);
	if (del_timer(&dev->watchdog_timer))
		netdev_put(dev, &dev->watchdog_dev_tracker);
	netif_tx_unlock_bh(dev);
}

/**
 *	netif_carrier_on - set carrier
 *	@dev: network device
 *
 * Device has detected acquisition of carrier.
 */
void netif_carrier_on(struct net_device *dev)
{
	if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
		if (dev->reg_state == NETREG_UNINITIALIZED)
			return;
		atomic_inc(&dev->carrier_up_count);
		linkwatch_fire_event(dev);
		if (netif_running(dev))
			__netdev_watchdog_up(dev);
	}
}
EXPORT_SYMBOL(netif_carrier_on);

/**
 *	netif_carrier_off - clear carrier
 *	@dev: network device
 *
 * Device has detected loss of carrier.
 */
void netif_carrier_off(struct net_device *dev)
{
	if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
		if (dev->reg_state == NETREG_UNINITIALIZED)
			return;
		atomic_inc(&dev->carrier_down_count);
		linkwatch_fire_event(dev);
	}
}
EXPORT_SYMBOL(netif_carrier_off);

/**
 *	netif_carrier_event - report carrier state event
 *	@dev: network device
 *
 * Device has detected a carrier event but the carrier state wasn't changed.
 * Use in drivers when querying carrier state asynchronously, to avoid missing
 * events (link flaps) if link recovers before it's queried.
 */
void netif_carrier_event(struct net_device *dev)
{
	if (dev->reg_state == NETREG_UNINITIALIZED)
		return;
	atomic_inc(&dev->carrier_up_count);
	atomic_inc(&dev->carrier_down_count);
	linkwatch_fire_event(dev);
}
EXPORT_SYMBOL_GPL(netif_carrier_event);

/* "NOOP" scheduler: the best scheduler, recommended for all interfaces
   under all circumstances. It is difficult to invent anything faster or
   cheaper.
 */

static int noop_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
			struct sk_buff **to_free)
{
	__qdisc_drop(skb, to_free);
	return NET_XMIT_CN;
}

static struct sk_buff *noop_dequeue(struct Qdisc *qdisc)
{
	return NULL;
}

struct Qdisc_ops noop_qdisc_ops __read_mostly = {
	.id		=	"noop",
	.priv_size	=	0,
	.enqueue	=	noop_enqueue,
	.dequeue	=	noop_dequeue,
	.peek		=	noop_dequeue,
	.owner		=	THIS_MODULE,
};

static struct netdev_queue noop_netdev_queue = {
	RCU_POINTER_INITIALIZER(qdisc, &noop_qdisc),
	.qdisc_sleeping	=	&noop_qdisc,
};

struct Qdisc noop_qdisc = {
	.enqueue	=	noop_enqueue,
	.dequeue	=	noop_dequeue,
	.flags		=	TCQ_F_BUILTIN,
	.ops		=	&noop_qdisc_ops,
	.q.lock		=	__SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
	.dev_queue	=	&noop_netdev_queue,
	.busylock	=	__SPIN_LOCK_UNLOCKED(noop_qdisc.busylock),
	.gso_skb = {
		.next = (struct sk_buff *)&noop_qdisc.gso_skb,
		.prev = (struct sk_buff *)&noop_qdisc.gso_skb,
		.qlen = 0,
		.lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.gso_skb.lock),
	},
	.skb_bad_txq = {
		.next = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
		.prev = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
		.qlen = 0,
		.lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.skb_bad_txq.lock),
	},
};
EXPORT_SYMBOL(noop_qdisc);

static int noqueue_init(struct Qdisc *qdisc, struct nlattr *opt,
			struct netlink_ext_ack *extack)
{
	/* register_qdisc() assigns a default of noop_enqueue if unset,
	 * but __dev_queue_xmit() treats noqueue only as such
	 * if this is NULL - so clear it here. */
	qdisc->enqueue = NULL;
	return 0;
}

struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
	.id		=	"noqueue",
	.priv_size	=	0,
	.init		=	noqueue_init,
	.enqueue	=	noop_enqueue,
	.dequeue	=	noop_dequeue,
	.peek		=	noop_dequeue,
	.owner		=	THIS_MODULE,
};

static const u8 prio2band[TC_PRIO_MAX + 1] = {
	1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1
};

/* 3-band FIFO queue: old style, but should be a bit faster than
   generic prio+fifo combination.
 */

#define PFIFO_FAST_BANDS 3

/*
 * Private data for a pfifo_fast scheduler containing:
 *	- rings for priority bands
 */
struct pfifo_fast_priv {
	struct skb_array q[PFIFO_FAST_BANDS];
};

static inline struct skb_array *band2list(struct pfifo_fast_priv *priv,
					  int band)
{
	return &priv->q[band];
}

static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
			      struct sk_buff **to_free)
{
	int band = prio2band[skb->priority & TC_PRIO_MAX];
	struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
	struct skb_array *q = band2list(priv, band);
	unsigned int pkt_len = qdisc_pkt_len(skb);
	int err;

	err = skb_array_produce(q, skb);

	if (unlikely(err)) {
		if (qdisc_is_percpu_stats(qdisc))
			return qdisc_drop_cpu(skb, qdisc, to_free);
		else
			return qdisc_drop(skb, qdisc, to_free);
	}

	qdisc_update_stats_at_enqueue(qdisc, pkt_len);
	return NET_XMIT_SUCCESS;
}

static struct sk_buff *pfifo_fast_dequeue(struct Qdisc *qdisc)
{
	struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
	struct sk_buff *skb = NULL;
	bool need_retry = true;
	int band;

retry:
	for (band = 0; band < PFIFO_FAST_BANDS && !skb; band++) {
		struct skb_array *q = band2list(priv, band);

		if (__skb_array_empty(q))
			continue;

		skb = __skb_array_consume(q);
	}
	if (likely(skb)) {
		qdisc_update_stats_at_dequeue(qdisc, skb);
	} else if (need_retry &&
		   READ_ONCE(qdisc->state) & QDISC_STATE_NON_EMPTY) {
		/* Delay clearing the STATE_MISSED here to reduce
		 * the overhead of the second spin_trylock() in
		 * qdisc_run_begin() and __netif_schedule() calling
		 * in qdisc_run_end().
		 */
		clear_bit(__QDISC_STATE_MISSED, &qdisc->state);
		clear_bit(__QDISC_STATE_DRAINING, &qdisc->state);

		/* Make sure dequeuing happens after clearing
		 * STATE_MISSED.
		 */
		smp_mb__after_atomic();

		need_retry = false;

		goto retry;
	}

	return skb;
}

static struct sk_buff *pfifo_fast_peek(struct Qdisc *qdisc)
{
	struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
	struct sk_buff *skb = NULL;
	int band;

	for (band = 0; band < PFIFO_FAST_BANDS && !skb; band++) {
		struct skb_array *q = band2list(priv, band);

		skb = __skb_array_peek(q);
	}

	return skb;
}

static void pfifo_fast_reset(struct Qdisc *qdisc)
{
	int i, band;
	struct pfifo_fast_priv *priv = qdisc_priv(qdisc);

	for (band = 0; band < PFIFO_FAST_BANDS; band++) {
		struct skb_array *q = band2list(priv, band);
		struct sk_buff *skb;

		/* NULL ring is possible if destroy path is due to a failed
		 * skb_array_init() in pfifo_fast_init() case.
		 */
		if (!q->ring.queue)
			continue;

		while ((skb = __skb_array_consume(q)) != NULL)
			kfree_skb(skb);
	}

	if (qdisc_is_percpu_stats(qdisc)) {
		for_each_possible_cpu(i) {
			struct gnet_stats_queue *q;

			q = per_cpu_ptr(qdisc->cpu_qstats, i);
			q->backlog = 0;
			q->qlen = 0;
		}
	}
}

static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
{
	struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };

	memcpy(&opt.priomap, prio2band, TC_PRIO_MAX + 1);
	if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
		goto nla_put_failure;
	return skb->len;

nla_put_failure:
	return -1;
}

static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt,
			   struct netlink_ext_ack *extack)
{
	unsigned int qlen = qdisc_dev(qdisc)->tx_queue_len;
	struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
	int prio;

	/* guard against zero length rings */
	if (!qlen)
		return -EINVAL;

	for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
		struct skb_array *q = band2list(priv, prio);
		int err;

		err = skb_array_init(q, qlen, GFP_KERNEL);
		if (err)
			return -ENOMEM;
	}

	/* Can by-pass the queue discipline */
	qdisc->flags |= TCQ_F_CAN_BYPASS;
	return 0;
}

static void pfifo_fast_destroy(struct Qdisc *sch)
{
	struct pfifo_fast_priv *priv = qdisc_priv(sch);
	int prio;

	for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
		struct skb_array *q = band2list(priv, prio);

		/* NULL ring is possible if destroy path is due to a failed
		 * skb_array_init() in pfifo_fast_init() case.
		 */
		if (!q->ring.queue)
			continue;
		/* Destroy ring but no need to kfree_skb because a call to
		 * pfifo_fast_reset() has already done that work.
		 */
		ptr_ring_cleanup(&q->ring, NULL);
	}
}

static int pfifo_fast_change_tx_queue_len(struct Qdisc *sch,
					  unsigned int new_len)
{
	struct pfifo_fast_priv *priv = qdisc_priv(sch);
	struct skb_array *bands[PFIFO_FAST_BANDS];
	int prio;

	for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
		struct skb_array *q = band2list(priv, prio);

		bands[prio] = q;
	}

	return skb_array_resize_multiple(bands, PFIFO_FAST_BANDS, new_len,
					 GFP_KERNEL);
}

struct Qdisc_ops pfifo_fast_ops __read_mostly = {
	.id		=	"pfifo_fast",
	.priv_size	=	sizeof(struct pfifo_fast_priv),
	.enqueue	=	pfifo_fast_enqueue,
	.dequeue	=	pfifo_fast_dequeue,
	.peek		=	pfifo_fast_peek,
	.init		=	pfifo_fast_init,
	.destroy	=	pfifo_fast_destroy,
	.reset		=	pfifo_fast_reset,
	.dump		=	pfifo_fast_dump,
	.change_tx_queue_len =  pfifo_fast_change_tx_queue_len,
	.owner		=	THIS_MODULE,
	.static_flags	=	TCQ_F_NOLOCK | TCQ_F_CPUSTATS,
};
EXPORT_SYMBOL(pfifo_fast_ops);

static struct lock_class_key qdisc_tx_busylock;

struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
			  const struct Qdisc_ops *ops,
			  struct netlink_ext_ack *extack)
{
	struct Qdisc *sch;
	unsigned int size = sizeof(*sch) + ops->priv_size;
	int err = -ENOBUFS;
	struct net_device *dev;

	if (!dev_queue) {
		NL_SET_ERR_MSG(extack, "No device queue given");
		err = -EINVAL;
		goto errout;
	}

	dev = dev_queue->dev;
	sch = kzalloc_node(size, GFP_KERNEL, netdev_queue_numa_node_read(dev_queue));

	if (!sch)
		goto errout;
	__skb_queue_head_init(&sch->gso_skb);
	__skb_queue_head_init(&sch->skb_bad_txq);
	qdisc_skb_head_init(&sch->q);
	gnet_stats_basic_sync_init(&sch->bstats);
	spin_lock_init(&sch->q.lock);

	if (ops->static_flags & TCQ_F_CPUSTATS) {
		sch->cpu_bstats =
			netdev_alloc_pcpu_stats(struct gnet_stats_basic_sync);
		if (!sch->cpu_bstats)
			goto errout1;

		sch->cpu_qstats = alloc_percpu(struct gnet_stats_queue);
		if (!sch->cpu_qstats) {
			free_percpu(sch->cpu_bstats);
			goto errout1;
		}
	}

	spin_lock_init(&sch->busylock);
	lockdep_set_class(&sch->busylock,
			  dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);

	/* seqlock has the same scope of busylock, for NOLOCK qdisc */
	spin_lock_init(&sch->seqlock);
	lockdep_set_class(&sch->seqlock,
			  dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);

	sch->ops = ops;
	sch->flags = ops->static_flags;
	sch->enqueue = ops->enqueue;
	sch->dequeue = ops->dequeue;
	sch->dev_queue = dev_queue;
	netdev_hold(dev, &sch->dev_tracker, GFP_KERNEL);
	refcount_set(&sch->refcnt, 1);

	return sch;
errout1:
	kfree(sch);
errout:
	return ERR_PTR(err);
}

struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
				const struct Qdisc_ops *ops,
				unsigned int parentid,
				struct netlink_ext_ack *extack)
{
	struct Qdisc *sch;

	if (!try_module_get(ops->owner)) {
		NL_SET_ERR_MSG(extack, "Failed to increase module reference counter");
		return NULL;
	}

	sch = qdisc_alloc(dev_queue, ops, extack);
	if (IS_ERR(sch)) {
		module_put(ops->owner);
		return NULL;
	}
	sch->parent = parentid;

	if (!ops->init || ops->init(sch, NULL, extack) == 0) {
		trace_qdisc_create(ops, dev_queue->dev, parentid);
		return sch;
	}

	qdisc_put(sch);
	return NULL;
}
EXPORT_SYMBOL(qdisc_create_dflt);

/* Under qdisc_lock(qdisc) and BH! */

void qdisc_reset(struct Qdisc *qdisc)
{
	const struct Qdisc_ops *ops = qdisc->ops;

	trace_qdisc_reset(qdisc);

	if (ops->reset)
		ops->reset(qdisc);

	__skb_queue_purge(&qdisc->gso_skb);
	__skb_queue_purge(&qdisc->skb_bad_txq);

	qdisc->q.qlen = 0;
	qdisc->qstats.backlog = 0;
}
EXPORT_SYMBOL(qdisc_reset);

void qdisc_free(struct Qdisc *qdisc)
{
	if (qdisc_is_percpu_stats(qdisc)) {
		free_percpu(qdisc->cpu_bstats);
		free_percpu(qdisc->cpu_qstats);
	}

	kfree(qdisc);
}

static void qdisc_free_cb(struct rcu_head *head)
{
	struct Qdisc *q = container_of(head, struct Qdisc, rcu);

	qdisc_free(q);
}

static void qdisc_destroy(struct Qdisc *qdisc)
{
	const struct Qdisc_ops  *ops = qdisc->ops;

#ifdef CONFIG_NET_SCHED
	qdisc_hash_del(qdisc);

	qdisc_put_stab(rtnl_dereference(qdisc->stab));
#endif
	gen_kill_estimator(&qdisc->rate_est);

	qdisc_reset(qdisc);

	if (ops->destroy)
		ops->destroy(qdisc);

	module_put(ops->owner);
	netdev_put(qdisc_dev(qdisc), &qdisc->dev_tracker);

	trace_qdisc_destroy(qdisc);

	call_rcu(&qdisc->rcu, qdisc_free_cb);
}

void qdisc_put(struct Qdisc *qdisc)
{
	if (!qdisc)
		return;

	if (qdisc->flags & TCQ_F_BUILTIN ||
	    !refcount_dec_and_test(&qdisc->refcnt))
		return;

	qdisc_destroy(qdisc);
}
EXPORT_SYMBOL(qdisc_put);

/* Version of qdisc_put() that is called with rtnl mutex unlocked.
 * Intended to be used as optimization, this function only takes rtnl lock if
 * qdisc reference counter reached zero.
 */

void qdisc_put_unlocked(struct Qdisc *qdisc)
{
	if (qdisc->flags & TCQ_F_BUILTIN ||
	    !refcount_dec_and_rtnl_lock(&qdisc->refcnt))
		return;

	qdisc_destroy(qdisc);
	rtnl_unlock();
}
EXPORT_SYMBOL(qdisc_put_unlocked);

/* Attach toplevel qdisc to device queue. */
struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
			      struct Qdisc *qdisc)
{
	struct Qdisc *oqdisc = dev_queue->qdisc_sleeping;
	spinlock_t *root_lock;

	root_lock = qdisc_lock(oqdisc);
	spin_lock_bh(root_lock);

	/* ... and graft new one */
	if (qdisc == NULL)
		qdisc = &noop_qdisc;
	dev_queue->qdisc_sleeping = qdisc;
	rcu_assign_pointer(dev_queue->qdisc, &noop_qdisc);

	spin_unlock_bh(root_lock);

	return oqdisc;
}
EXPORT_SYMBOL(dev_graft_qdisc);

static void attach_one_default_qdisc(struct net_device *dev,
				     struct netdev_queue *dev_queue,
				     void *_unused)
{
	struct Qdisc *qdisc;
	const struct Qdisc_ops *ops = default_qdisc_ops;

	if (dev->priv_flags & IFF_NO_QUEUE)
		ops = &noqueue_qdisc_ops;
	else if(dev->type == ARPHRD_CAN)
		ops = &pfifo_fast_ops;

	qdisc = qdisc_create_dflt(dev_queue, ops, TC_H_ROOT, NULL);
	if (!qdisc)
		return;

	if (!netif_is_multiqueue(dev))
		qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
	dev_queue->qdisc_sleeping = qdisc;
}

static void attach_default_qdiscs(struct net_device *dev)
{
	struct netdev_queue *txq;
	struct Qdisc *qdisc;

	txq = netdev_get_tx_queue(dev, 0);

	if (!netif_is_multiqueue(dev) ||
	    dev->priv_flags & IFF_NO_QUEUE) {
		netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
		qdisc = txq->qdisc_sleeping;
		rcu_assign_pointer(dev->qdisc, qdisc);
		qdisc_refcount_inc(qdisc);
	} else {
		qdisc = qdisc_create_dflt(txq, &mq_qdisc_ops, TC_H_ROOT, NULL);
		if (qdisc) {
			rcu_assign_pointer(dev->qdisc, qdisc);
			qdisc->ops->attach(qdisc);
		}
	}
	qdisc = rtnl_dereference(dev->qdisc);

	/* Detect default qdisc setup/init failed and fallback to "noqueue" */
	if (qdisc == &noop_qdisc) {
		netdev_warn(dev, "default qdisc (%s) fail, fallback to %s\n",
			    default_qdisc_ops->id, noqueue_qdisc_ops.id);
		dev->priv_flags |= IFF_NO_QUEUE;
		netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
		qdisc = txq->qdisc_sleeping;
		rcu_assign_pointer(dev->qdisc, qdisc);
		qdisc_refcount_inc(qdisc);
		dev->priv_flags ^= IFF_NO_QUEUE;
	}

#ifdef CONFIG_NET_SCHED
	if (qdisc != &noop_qdisc)
		qdisc_hash_add(qdisc, false);
#endif
}

static void transition_one_qdisc(struct net_device *dev,
				 struct netdev_queue *dev_queue,
				 void *_need_watchdog)
{
	struct Qdisc *new_qdisc = dev_queue->qdisc_sleeping;
	int *need_watchdog_p = _need_watchdog;

	if (!(new_qdisc->flags & TCQ_F_BUILTIN))
		clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state);

	rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
	if (need_watchdog_p) {
		WRITE_ONCE(dev_queue->trans_start, 0);
		*need_watchdog_p = 1;
	}
}

void dev_activate(struct net_device *dev)
{
	int need_watchdog;

	/* No queueing discipline is attached to device;
	 * create default one for devices, which need queueing
	 * and noqueue_qdisc for virtual interfaces
	 */

	if (rtnl_dereference(dev->qdisc) == &noop_qdisc)
		attach_default_qdiscs(dev);

	if (!netif_carrier_ok(dev))
		/* Delay activation until next carrier-on event */
		return;

	need_watchdog = 0;
	netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
	if (dev_ingress_queue(dev))
		transition_one_qdisc(dev, dev_ingress_queue(dev), NULL);

	if (need_watchdog) {
		netif_trans_update(dev);
		dev_watchdog_up(dev);
	}
}
EXPORT_SYMBOL(dev_activate);

static void qdisc_deactivate(struct Qdisc *qdisc)
{
	if (qdisc->flags & TCQ_F_BUILTIN)
		return;

	set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
}

static void dev_deactivate_queue(struct net_device *dev,
				 struct netdev_queue *dev_queue,
				 void *_qdisc_default)
{
	struct Qdisc *qdisc_default = _qdisc_default;
	struct Qdisc *qdisc;

	qdisc = rtnl_dereference(dev_queue->qdisc);
	if (qdisc) {
		qdisc_deactivate(qdisc);
		rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
	}
}

static void dev_reset_queue(struct net_device *dev,
			    struct netdev_queue *dev_queue,
			    void *_unused)
{
	struct Qdisc *qdisc;
	bool nolock;

	qdisc = dev_queue->qdisc_sleeping;
	if (!qdisc)
		return;

	nolock = qdisc->flags & TCQ_F_NOLOCK;

	if (nolock)
		spin_lock_bh(&qdisc->seqlock);
	spin_lock_bh(qdisc_lock(qdisc));

	qdisc_reset(qdisc);

	spin_unlock_bh(qdisc_lock(qdisc));
	if (nolock) {
		clear_bit(__QDISC_STATE_MISSED, &qdisc->state);
		clear_bit(__QDISC_STATE_DRAINING, &qdisc->state);
		spin_unlock_bh(&qdisc->seqlock);
	}
}

static bool some_qdisc_is_busy(struct net_device *dev)
{
	unsigned int i;

	for (i = 0; i < dev->num_tx_queues; i++) {
		struct netdev_queue *dev_queue;
		spinlock_t *root_lock;
		struct Qdisc *q;
		int val;

		dev_queue = netdev_get_tx_queue(dev, i);
		q = dev_queue->qdisc_sleeping;

		root_lock = qdisc_lock(q);
		spin_lock_bh(root_lock);

		val = (qdisc_is_running(q) ||
		       test_bit(__QDISC_STATE_SCHED, &q->state));

		spin_unlock_bh(root_lock);

		if (val)
			return true;
	}
	return false;
}

/**
 * 	dev_deactivate_many - deactivate transmissions on several devices
 * 	@head: list of devices to deactivate
 *
 *	This function returns only when all outstanding transmissions
 *	have completed, unless all devices are in dismantle phase.
 */
void dev_deactivate_many(struct list_head *head)
{
	struct net_device *dev;

	list_for_each_entry(dev, head, close_list) {
		netdev_for_each_tx_queue(dev, dev_deactivate_queue,
					 &noop_qdisc);
		if (dev_ingress_queue(dev))
			dev_deactivate_queue(dev, dev_ingress_queue(dev),
					     &noop_qdisc);

		dev_watchdog_down(dev);
	}

	/* Wait for outstanding qdisc-less dev_queue_xmit calls or
	 * outstanding qdisc enqueuing calls.
	 * This is avoided if all devices are in dismantle phase :
	 * Caller will call synchronize_net() for us
	 */
	synchronize_net();

	list_for_each_entry(dev, head, close_list) {
		netdev_for_each_tx_queue(dev, dev_reset_queue, NULL);

		if (dev_ingress_queue(dev))
			dev_reset_queue(dev, dev_ingress_queue(dev), NULL);
	}

	/* Wait for outstanding qdisc_run calls. */
	list_for_each_entry(dev, head, close_list) {
		while (some_qdisc_is_busy(dev)) {
			/* wait_event() would avoid this sleep-loop but would
			 * require expensive checks in the fast paths of packet
			 * processing which isn't worth it.
			 */
			schedule_timeout_uninterruptible(1);
		}
	}
}

void dev_deactivate(struct net_device *dev)
{
	LIST_HEAD(single);

	list_add(&dev->close_list, &single);
	dev_deactivate_many(&single);
	list_del(&single);
}
EXPORT_SYMBOL(dev_deactivate);

static int qdisc_change_tx_queue_len(struct net_device *dev,
				     struct netdev_queue *dev_queue)
{
	struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
	const struct Qdisc_ops *ops = qdisc->ops;

	if (ops->change_tx_queue_len)
		return ops->change_tx_queue_len(qdisc, dev->tx_queue_len);
	return 0;
}

void dev_qdisc_change_real_num_tx(struct net_device *dev,
				  unsigned int new_real_tx)
{
	struct Qdisc *qdisc = rtnl_dereference(dev->qdisc);

	if (qdisc->ops->change_real_num_tx)
		qdisc->ops->change_real_num_tx(qdisc, new_real_tx);
}

void mq_change_real_num_tx(struct Qdisc *sch, unsigned int new_real_tx)
{
#ifdef CONFIG_NET_SCHED
	struct net_device *dev = qdisc_dev(sch);
	struct Qdisc *qdisc;
	unsigned int i;

	for (i = new_real_tx; i < dev->real_num_tx_queues; i++) {
		qdisc = netdev_get_tx_queue(dev, i)->qdisc_sleeping;
		/* Only update the default qdiscs we created,
		 * qdiscs with handles are always hashed.
		 */
		if (qdisc != &noop_qdisc && !qdisc->handle)
			qdisc_hash_del(qdisc);
	}
	for (i = dev->real_num_tx_queues; i < new_real_tx; i++) {
		qdisc = netdev_get_tx_queue(dev, i)->qdisc_sleeping;
		if (qdisc != &noop_qdisc && !qdisc->handle)
			qdisc_hash_add(qdisc, false);
	}
#endif
}
EXPORT_SYMBOL(mq_change_real_num_tx);

int dev_qdisc_change_tx_queue_len(struct net_device *dev)
{
	bool up = dev->flags & IFF_UP;
	unsigned int i;
	int ret = 0;

	if (up)
		dev_deactivate(dev);

	for (i = 0; i < dev->num_tx_queues; i++) {
		ret = qdisc_change_tx_queue_len(dev, &dev->_tx[i]);

		/* TODO: revert changes on a partial failure */
		if (ret)
			break;
	}

	if (up)
		dev_activate(dev);
	return ret;
}

static void dev_init_scheduler_queue(struct net_device *dev,
				     struct netdev_queue *dev_queue,
				     void *_qdisc)
{
	struct Qdisc *qdisc = _qdisc;

	rcu_assign_pointer(dev_queue->qdisc, qdisc);
	dev_queue->qdisc_sleeping = qdisc;
}

void dev_init_scheduler(struct net_device *dev)
{
	rcu_assign_pointer(dev->qdisc, &noop_qdisc);
	netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
	if (dev_ingress_queue(dev))
		dev_init_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);

	timer_setup(&dev->watchdog_timer, dev_watchdog, 0);
}

static void shutdown_scheduler_queue(struct net_device *dev,
				     struct netdev_queue *dev_queue,
				     void *_qdisc_default)
{
	struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
	struct Qdisc *qdisc_default = _qdisc_default;

	if (qdisc) {
		rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
		dev_queue->qdisc_sleeping = qdisc_default;

		qdisc_put(qdisc);
	}
}

void dev_shutdown(struct net_device *dev)
{
	netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
	if (dev_ingress_queue(dev))
		shutdown_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
	qdisc_put(rtnl_dereference(dev->qdisc));
	rcu_assign_pointer(dev->qdisc, &noop_qdisc);

	WARN_ON(timer_pending(&dev->watchdog_timer));
}

/**
 * psched_ratecfg_precompute__() - Pre-compute values for reciprocal division
 * @rate:   Rate to compute reciprocal division values of
 * @mult:   Multiplier for reciprocal division
 * @shift:  Shift for reciprocal division
 *
 * The multiplier and shift for reciprocal division by rate are stored
 * in mult and shift.
 *
 * The deal here is to replace a divide by a reciprocal one
 * in fast path (a reciprocal divide is a multiply and a shift)
 *
 * Normal formula would be :
 *  time_in_ns = (NSEC_PER_SEC * len) / rate_bps
 *
 * We compute mult/shift to use instead :
 *  time_in_ns = (len * mult) >> shift;
 *
 * We try to get the highest possible mult value for accuracy,
 * but have to make sure no overflows will ever happen.
 *
 * reciprocal_value() is not used here it doesn't handle 64-bit values.
 */
static void psched_ratecfg_precompute__(u64 rate, u32 *mult, u8 *shift)
{
	u64 factor = NSEC_PER_SEC;

	*mult = 1;
	*shift = 0;

	if (rate <= 0)
		return;

	for (;;) {
		*mult = div64_u64(factor, rate);
		if (*mult & (1U << 31) || factor & (1ULL << 63))
			break;
		factor <<= 1;
		(*shift)++;
	}
}

void psched_ratecfg_precompute(struct psched_ratecfg *r,
			       const struct tc_ratespec *conf,
			       u64 rate64)
{
	memset(r, 0, sizeof(*r));
	r->overhead = conf->overhead;
	r->mpu = conf->mpu;
	r->rate_bytes_ps = max_t(u64, conf->rate, rate64);
	r->linklayer = (conf->linklayer & TC_LINKLAYER_MASK);
	psched_ratecfg_precompute__(r->rate_bytes_ps, &r->mult, &r->shift);
}
EXPORT_SYMBOL(psched_ratecfg_precompute);

void psched_ppscfg_precompute(struct psched_pktrate *r, u64 pktrate64)
{
	r->rate_pkts_ps = pktrate64;
	psched_ratecfg_precompute__(r->rate_pkts_ps, &r->mult, &r->shift);
}
EXPORT_SYMBOL(psched_ppscfg_precompute);

void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp,
			  struct tcf_proto *tp_head)
{
	/* Protected with chain0->filter_chain_lock.
	 * Can't access chain directly because tp_head can be NULL.
	 */
	struct mini_Qdisc *miniq_old =
		rcu_dereference_protected(*miniqp->p_miniq, 1);
	struct mini_Qdisc *miniq;

	if (!tp_head) {
		RCU_INIT_POINTER(*miniqp->p_miniq, NULL);
	} else {
		miniq = miniq_old != &miniqp->miniq1 ?
			&miniqp->miniq1 : &miniqp->miniq2;

		/* We need to make sure that readers won't see the miniq
		 * we are about to modify. So ensure that at least one RCU
		 * grace period has elapsed since the miniq was made
		 * inactive.
		 */
		if (IS_ENABLED(CONFIG_PREEMPT_RT))
			cond_synchronize_rcu(miniq->rcu_state);
		else if (!poll_state_synchronize_rcu(miniq->rcu_state))
			synchronize_rcu_expedited();

		miniq->filter_list = tp_head;
		rcu_assign_pointer(*miniqp->p_miniq, miniq);
	}

	if (miniq_old)
		/* This is counterpart of the rcu sync above. We need to
		 * block potential new user of miniq_old until all readers
		 * are not seeing it.
		 */
		miniq_old->rcu_state = start_poll_synchronize_rcu();
}
EXPORT_SYMBOL(mini_qdisc_pair_swap);

void mini_qdisc_pair_block_init(struct mini_Qdisc_pair *miniqp,
				struct tcf_block *block)
{
	miniqp->miniq1.block = block;
	miniqp->miniq2.block = block;
}
EXPORT_SYMBOL(mini_qdisc_pair_block_init);

void mini_qdisc_pair_init(struct mini_Qdisc_pair *miniqp, struct Qdisc *qdisc,
			  struct mini_Qdisc __rcu **p_miniq)
{
	miniqp->miniq1.cpu_bstats = qdisc->cpu_bstats;
	miniqp->miniq1.cpu_qstats = qdisc->cpu_qstats;
	miniqp->miniq2.cpu_bstats = qdisc->cpu_bstats;
	miniqp->miniq2.cpu_qstats = qdisc->cpu_qstats;
	miniqp->miniq1.rcu_state = get_state_synchronize_rcu();
	miniqp->miniq2.rcu_state = miniqp->miniq1.rcu_state;
	miniqp->p_miniq = p_miniq;
}
EXPORT_SYMBOL(mini_qdisc_pair_init);