Home Home > GIT Browse
summaryrefslogtreecommitdiff
blob: 14afeeb7d6ef5b91929702af25f96ef4eeb711ec (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
/*
 * Generic infrastructure for lifetime debugging of objects.
 *
 * Started by Thomas Gleixner
 *
 * Copyright (C) 2008, Thomas Gleixner <tglx@linutronix.de>
 *
 * For licencing details see kernel-base/COPYING
 */

#define pr_fmt(fmt) "ODEBUG: " fmt

#include <linux/debugobjects.h>
#include <linux/interrupt.h>
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/seq_file.h>
#include <linux/debugfs.h>
#include <linux/slab.h>
#include <linux/hash.h>
#include <linux/kmemleak.h>

#define ODEBUG_HASH_BITS	14
#define ODEBUG_HASH_SIZE	(1 << ODEBUG_HASH_BITS)

#define ODEBUG_POOL_SIZE	1024
#define ODEBUG_POOL_MIN_LEVEL	256

#define ODEBUG_CHUNK_SHIFT	PAGE_SHIFT
#define ODEBUG_CHUNK_SIZE	(1 << ODEBUG_CHUNK_SHIFT)
#define ODEBUG_CHUNK_MASK	(~(ODEBUG_CHUNK_SIZE - 1))

struct debug_bucket {
	struct hlist_head	list;
	raw_spinlock_t		lock;
};

static struct debug_bucket	obj_hash[ODEBUG_HASH_SIZE];

static struct debug_obj		obj_static_pool[ODEBUG_POOL_SIZE] __initdata;

static DEFINE_RAW_SPINLOCK(pool_lock);

static HLIST_HEAD(obj_pool);
static HLIST_HEAD(obj_to_free);

static int			obj_pool_min_free = ODEBUG_POOL_SIZE;
static int			obj_pool_free = ODEBUG_POOL_SIZE;
static int			obj_pool_used;
static int			obj_pool_max_used;
/* The number of objs on the global free list */
static int			obj_nr_tofree;
static struct kmem_cache	*obj_cache;

static int			debug_objects_maxchain __read_mostly;
static int __maybe_unused	debug_objects_maxchecked __read_mostly;
static int			debug_objects_fixups __read_mostly;
static int			debug_objects_warnings __read_mostly;
static int			debug_objects_enabled __read_mostly
				= CONFIG_DEBUG_OBJECTS_ENABLE_DEFAULT;
static int			debug_objects_pool_size __read_mostly
				= ODEBUG_POOL_SIZE;
static int			debug_objects_pool_min_level __read_mostly
				= ODEBUG_POOL_MIN_LEVEL;
static struct debug_obj_descr	*descr_test  __read_mostly;

/*
 * Track numbers of kmem_cache_alloc()/free() calls done.
 */
static int			debug_objects_allocated;
static int			debug_objects_freed;

static void free_obj_work(struct work_struct *work);
static DECLARE_WORK(debug_obj_work, free_obj_work);

static int __init enable_object_debug(char *str)
{
	debug_objects_enabled = 1;
	return 0;
}

static int __init disable_object_debug(char *str)
{
	debug_objects_enabled = 0;
	return 0;
}

early_param("debug_objects", enable_object_debug);
early_param("no_debug_objects", disable_object_debug);

static const char *obj_states[ODEBUG_STATE_MAX] = {
	[ODEBUG_STATE_NONE]		= "none",
	[ODEBUG_STATE_INIT]		= "initialized",
	[ODEBUG_STATE_INACTIVE]		= "inactive",
	[ODEBUG_STATE_ACTIVE]		= "active",
	[ODEBUG_STATE_DESTROYED]	= "destroyed",
	[ODEBUG_STATE_NOTAVAILABLE]	= "not available",
};

static void fill_pool(void)
{
	gfp_t gfp = GFP_ATOMIC | __GFP_NORETRY | __GFP_NOWARN;
	struct debug_obj *new, *obj;
	unsigned long flags;

	if (likely(obj_pool_free >= debug_objects_pool_min_level))
		return;

	/*
	 * Reuse objs from the global free list; they will be reinitialized
	 * when allocating.
	 */
	while (obj_nr_tofree && (obj_pool_free < obj_pool_min_free)) {
		raw_spin_lock_irqsave(&pool_lock, flags);
		/*
		 * Recheck with the lock held as the worker thread might have
		 * won the race and freed the global free list already.
		 */
		if (obj_nr_tofree) {
			obj = hlist_entry(obj_to_free.first, typeof(*obj), node);
			hlist_del(&obj->node);
			obj_nr_tofree--;
			hlist_add_head(&obj->node, &obj_pool);
			obj_pool_free++;
		}
		raw_spin_unlock_irqrestore(&pool_lock, flags);
	}

	if (unlikely(!obj_cache))
		return;

	while (obj_pool_free < debug_objects_pool_min_level) {

		new = kmem_cache_zalloc(obj_cache, gfp);
		if (!new)
			return;

		raw_spin_lock_irqsave(&pool_lock, flags);
		hlist_add_head(&new->node, &obj_pool);
		debug_objects_allocated++;
		obj_pool_free++;
		raw_spin_unlock_irqrestore(&pool_lock, flags);
	}
}

/*
 * Lookup an object in the hash bucket.
 */
static struct debug_obj *lookup_object(void *addr, struct debug_bucket *b)
{
	struct debug_obj *obj;
	int cnt = 0;

	hlist_for_each_entry(obj, &b->list, node) {
		cnt++;
		if (obj->object == addr)
			return obj;
	}
	if (cnt > debug_objects_maxchain)
		debug_objects_maxchain = cnt;

	return NULL;
}

/*
 * Allocate a new object. If the pool is empty, switch off the debugger.
 * Must be called with interrupts disabled.
 */
static struct debug_obj *
alloc_object(void *addr, struct debug_bucket *b, struct debug_obj_descr *descr)
{
	struct debug_obj *obj = NULL;

	raw_spin_lock(&pool_lock);
	if (obj_pool.first) {
		obj	    = hlist_entry(obj_pool.first, typeof(*obj), node);

		obj->object = addr;
		obj->descr  = descr;
		obj->state  = ODEBUG_STATE_NONE;
		obj->astate = 0;
		hlist_del(&obj->node);

		hlist_add_head(&obj->node, &b->list);

		obj_pool_used++;
		if (obj_pool_used > obj_pool_max_used)
			obj_pool_max_used = obj_pool_used;

		obj_pool_free--;
		if (obj_pool_free < obj_pool_min_free)
			obj_pool_min_free = obj_pool_free;
	}
	raw_spin_unlock(&pool_lock);

	return obj;
}

/*
 * workqueue function to free objects.
 *
 * To reduce contention on the global pool_lock, the actual freeing of
 * debug objects will be delayed if the pool_lock is busy.
 */
static void free_obj_work(struct work_struct *work)
{
	struct hlist_node *tmp;
	struct debug_obj *obj;
	unsigned long flags;
	HLIST_HEAD(tofree);

	if (!raw_spin_trylock_irqsave(&pool_lock, flags))
		return;

	/*
	 * The objs on the pool list might be allocated before the work is
	 * run, so recheck if pool list it full or not, if not fill pool
	 * list from the global free list
	 */
	while (obj_nr_tofree && obj_pool_free < debug_objects_pool_size) {
		obj = hlist_entry(obj_to_free.first, typeof(*obj), node);
		hlist_del(&obj->node);
		hlist_add_head(&obj->node, &obj_pool);
		obj_pool_free++;
		obj_nr_tofree--;
	}

	/*
	 * Pool list is already full and there are still objs on the free
	 * list. Move remaining free objs to a temporary list to free the
	 * memory outside the pool_lock held region.
	 */
	if (obj_nr_tofree) {
		hlist_move_list(&obj_to_free, &tofree);
		debug_objects_freed += obj_nr_tofree;
		obj_nr_tofree = 0;
	}
	raw_spin_unlock_irqrestore(&pool_lock, flags);

	hlist_for_each_entry_safe(obj, tmp, &tofree, node) {
		hlist_del(&obj->node);
		kmem_cache_free(obj_cache, obj);
	}
}

static bool __free_object(struct debug_obj *obj)
{
	unsigned long flags;
	bool work;

	raw_spin_lock_irqsave(&pool_lock, flags);
	work = (obj_pool_free > debug_objects_pool_size) && obj_cache;
	obj_pool_used--;

	if (work) {
		obj_nr_tofree++;
		hlist_add_head(&obj->node, &obj_to_free);
	} else {
		obj_pool_free++;
		hlist_add_head(&obj->node, &obj_pool);
	}
	raw_spin_unlock_irqrestore(&pool_lock, flags);
	return work;
}

/*
 * Put the object back into the pool and schedule work to free objects
 * if necessary.
 */
static void free_object(struct debug_obj *obj)
{
	if (__free_object(obj))
		schedule_work(&debug_obj_work);
}

/*
 * We run out of memory. That means we probably have tons of objects
 * allocated.
 */
static void debug_objects_oom(void)
{
	struct debug_bucket *db = obj_hash;
	struct hlist_node *tmp;
	HLIST_HEAD(freelist);
	struct debug_obj *obj;
	unsigned long flags;
	int i;

	pr_warn("Out of memory. ODEBUG disabled\n");

	for (i = 0; i < ODEBUG_HASH_SIZE; i++, db++) {
		raw_spin_lock_irqsave(&db->lock, flags);
		hlist_move_list(&db->list, &freelist);
		raw_spin_unlock_irqrestore(&db->lock, flags);

		/* Now free them */
		hlist_for_each_entry_safe(obj, tmp, &freelist, node) {
			hlist_del(&obj->node);
			free_object(obj);
		}
	}
}

/*
 * We use the pfn of the address for the hash. That way we can check
 * for freed objects simply by checking the affected bucket.
 */
static struct debug_bucket *get_bucket(unsigned long addr)
{
	unsigned long hash;

	hash = hash_long((addr >> ODEBUG_CHUNK_SHIFT), ODEBUG_HASH_BITS);
	return &obj_hash[hash];
}

static void debug_print_object(struct debug_obj *obj, char *msg)
{
	struct debug_obj_descr *descr = obj->descr;
	static int limit;

	if (limit < 5 && descr != descr_test) {
		void *hint = descr->debug_hint ?
			descr->debug_hint(obj->object) : NULL;
		limit++;
		WARN(1, KERN_ERR "ODEBUG: %s %s (active state %u) "
				 "object type: %s hint: %pS\n",
			msg, obj_states[obj->state], obj->astate,
			descr->name, hint);
	}
	debug_objects_warnings++;
}

/*
 * Try to repair the damage, so we have a better chance to get useful
 * debug output.
 */
static bool
debug_object_fixup(bool (*fixup)(void *addr, enum debug_obj_state state),
		   void * addr, enum debug_obj_state state)
{
	if (fixup && fixup(addr, state)) {
		debug_objects_fixups++;
		return true;
	}
	return false;
}

static void debug_object_is_on_stack(void *addr, int onstack)
{
	int is_on_stack;
	static int limit;

	if (limit > 4)
		return;

	is_on_stack = object_is_on_stack(addr);
	if (is_on_stack == onstack)
		return;

	limit++;
	if (is_on_stack)
		pr_warn("object %p is on stack %p, but NOT annotated.\n", addr,
			 task_stack_page(current));
	else
		pr_warn("object %p is NOT on stack %p, but annotated.\n", addr,
			 task_stack_page(current));

	WARN_ON(1);
}

static void
__debug_object_init(void *addr, struct debug_obj_descr *descr, int onstack)
{
	enum debug_obj_state state;
	struct debug_bucket *db;
	struct debug_obj *obj;
	unsigned long flags;

	fill_pool();

	db = get_bucket((unsigned long) addr);

	raw_spin_lock_irqsave(&db->lock, flags);

	obj = lookup_object(addr, db);
	if (!obj) {
		obj = alloc_object(addr, db, descr);
		if (!obj) {
			debug_objects_enabled = 0;
			raw_spin_unlock_irqrestore(&db->lock, flags);
			debug_objects_oom();
			return;
		}
		debug_object_is_on_stack(addr, onstack);
	}

	switch (obj->state) {
	case ODEBUG_STATE_NONE:
	case ODEBUG_STATE_INIT:
	case ODEBUG_STATE_INACTIVE:
		obj->state = ODEBUG_STATE_INIT;
		break;

	case ODEBUG_STATE_ACTIVE:
		debug_print_object(obj, "init");
		state = obj->state;
		raw_spin_unlock_irqrestore(&db->lock, flags);
		debug_object_fixup(descr->fixup_init, addr, state);
		return;

	case ODEBUG_STATE_DESTROYED:
		debug_print_object(obj, "init");
		break;
	default:
		break;
	}

	raw_spin_unlock_irqrestore(&db->lock, flags);
}

/**
 * debug_object_init - debug checks when an object is initialized
 * @addr:	address of the object
 * @descr:	pointer to an object specific debug description structure
 */
void debug_object_init(void *addr, struct debug_obj_descr *descr)
{
	if (!debug_objects_enabled)
		return;

	__debug_object_init(addr, descr, 0);
}
EXPORT_SYMBOL_GPL(debug_object_init);

/**
 * debug_object_init_on_stack - debug checks when an object on stack is
 *				initialized
 * @addr:	address of the object
 * @descr:	pointer to an object specific debug description structure
 */
void debug_object_init_on_stack(void *addr, struct debug_obj_descr *descr)
{
	if (!debug_objects_enabled)
		return;

	__debug_object_init(addr, descr, 1);
}
EXPORT_SYMBOL_GPL(debug_object_init_on_stack);

/**
 * debug_object_activate - debug checks when an object is activated
 * @addr:	address of the object
 * @descr:	pointer to an object specific debug description structure
 * Returns 0 for success, -EINVAL for check failed.
 */
int debug_object_activate(void *addr, struct debug_obj_descr *descr)
{
	enum debug_obj_state state;
	struct debug_bucket *db;
	struct debug_obj *obj;
	unsigned long flags;
	int ret;
	struct debug_obj o = { .object = addr,
			       .state = ODEBUG_STATE_NOTAVAILABLE,
			       .descr = descr };

	if (!debug_objects_enabled)
		return 0;

	db = get_bucket((unsigned long) addr);

	raw_spin_lock_irqsave(&db->lock, flags);

	obj = lookup_object(addr, db);
	if (obj) {
		switch (obj->state) {
		case ODEBUG_STATE_INIT:
		case ODEBUG_STATE_INACTIVE:
			obj->state = ODEBUG_STATE_ACTIVE;
			ret = 0;
			break;

		case ODEBUG_STATE_ACTIVE:
			debug_print_object(obj, "activate");
			state = obj->state;
			raw_spin_unlock_irqrestore(&db->lock, flags);
			ret = debug_object_fixup(descr->fixup_activate, addr, state);
			return ret ? 0 : -EINVAL;

		case ODEBUG_STATE_DESTROYED:
			debug_print_object(obj, "activate");
			ret = -EINVAL;
			break;
		default:
			ret = 0;
			break;
		}
		raw_spin_unlock_irqrestore(&db->lock, flags);
		return ret;
	}

	raw_spin_unlock_irqrestore(&db->lock, flags);
	/*
	 * We are here when a static object is activated. We
	 * let the type specific code confirm whether this is
	 * true or not. if true, we just make sure that the
	 * static object is tracked in the object tracker. If
	 * not, this must be a bug, so we try to fix it up.
	 */
	if (descr->is_static_object && descr->is_static_object(addr)) {
		/* track this static object */
		debug_object_init(addr, descr);
		debug_object_activate(addr, descr);
	} else {
		debug_print_object(&o, "activate");
		ret = debug_object_fixup(descr->fixup_activate, addr,
					ODEBUG_STATE_NOTAVAILABLE);
		return ret ? 0 : -EINVAL;
	}
	return 0;
}
EXPORT_SYMBOL_GPL(debug_object_activate);

/**
 * debug_object_deactivate - debug checks when an object is deactivated
 * @addr:	address of the object
 * @descr:	pointer to an object specific debug description structure
 */
void debug_object_deactivate(void *addr, struct debug_obj_descr *descr)
{
	struct debug_bucket *db;
	struct debug_obj *obj;
	unsigned long flags;

	if (!debug_objects_enabled)
		return;

	db = get_bucket((unsigned long) addr);

	raw_spin_lock_irqsave(&db->lock, flags);

	obj = lookup_object(addr, db);
	if (obj) {
		switch (obj->state) {
		case ODEBUG_STATE_INIT:
		case ODEBUG_STATE_INACTIVE:
		case ODEBUG_STATE_ACTIVE:
			if (!obj->astate)
				obj->state = ODEBUG_STATE_INACTIVE;
			else
				debug_print_object(obj, "deactivate");
			break;

		case ODEBUG_STATE_DESTROYED:
			debug_print_object(obj, "deactivate");
			break;
		default:
			break;
		}
	} else {
		struct debug_obj o = { .object = addr,
				       .state = ODEBUG_STATE_NOTAVAILABLE,
				       .descr = descr };

		debug_print_object(&o, "deactivate");
	}

	raw_spin_unlock_irqrestore(&db->lock, flags);
}
EXPORT_SYMBOL_GPL(debug_object_deactivate);

/**
 * debug_object_destroy - debug checks when an object is destroyed
 * @addr:	address of the object
 * @descr:	pointer to an object specific debug description structure
 */
void debug_object_destroy(void *addr, struct debug_obj_descr *descr)
{
	enum debug_obj_state state;
	struct debug_bucket *db;
	struct debug_obj *obj;
	unsigned long flags;

	if (!debug_objects_enabled)
		return;

	db = get_bucket((unsigned long) addr);

	raw_spin_lock_irqsave(&db->lock, flags);

	obj = lookup_object(addr, db);
	if (!obj)
		goto out_unlock;

	switch (obj->state) {
	case ODEBUG_STATE_NONE:
	case ODEBUG_STATE_INIT:
	case ODEBUG_STATE_INACTIVE:
		obj->state = ODEBUG_STATE_DESTROYED;
		break;
	case ODEBUG_STATE_ACTIVE:
		debug_print_object(obj, "destroy");
		state = obj->state;
		raw_spin_unlock_irqrestore(&db->lock, flags);
		debug_object_fixup(descr->fixup_destroy, addr, state);
		return;

	case ODEBUG_STATE_DESTROYED:
		debug_print_object(obj, "destroy");
		break;
	default:
		break;
	}
out_unlock:
	raw_spin_unlock_irqrestore(&db->lock, flags);
}
EXPORT_SYMBOL_GPL(debug_object_destroy);

/**
 * debug_object_free - debug checks when an object is freed
 * @addr:	address of the object
 * @descr:	pointer to an object specific debug description structure
 */
void debug_object_free(void *addr, struct debug_obj_descr *descr)
{
	enum debug_obj_state state;
	struct debug_bucket *db;
	struct debug_obj *obj;
	unsigned long flags;

	if (!debug_objects_enabled)
		return;

	db = get_bucket((unsigned long) addr);

	raw_spin_lock_irqsave(&db->lock, flags);

	obj = lookup_object(addr, db);
	if (!obj)
		goto out_unlock;

	switch (obj->state) {
	case ODEBUG_STATE_ACTIVE:
		debug_print_object(obj, "free");
		state = obj->state;
		raw_spin_unlock_irqrestore(&db->lock, flags);
		debug_object_fixup(descr->fixup_free, addr, state);
		return;
	default:
		hlist_del(&obj->node);
		raw_spin_unlock_irqrestore(&db->lock, flags);
		free_object(obj);
		return;
	}
out_unlock:
	raw_spin_unlock_irqrestore(&db->lock, flags);
}
EXPORT_SYMBOL_GPL(debug_object_free);

/**
 * debug_object_assert_init - debug checks when object should be init-ed
 * @addr:	address of the object
 * @descr:	pointer to an object specific debug description structure
 */
void debug_object_assert_init(void *addr, struct debug_obj_descr *descr)
{
	struct debug_bucket *db;
	struct debug_obj *obj;
	unsigned long flags;

	if (!debug_objects_enabled)
		return;

	db = get_bucket((unsigned long) addr);

	raw_spin_lock_irqsave(&db->lock, flags);

	obj = lookup_object(addr, db);
	if (!obj) {
		struct debug_obj o = { .object = addr,
				       .state = ODEBUG_STATE_NOTAVAILABLE,
				       .descr = descr };

		raw_spin_unlock_irqrestore(&db->lock, flags);
		/*
		 * Maybe the object is static, and we let the type specific
		 * code confirm. Track this static object if true, else invoke
		 * fixup.
		 */
		if (descr->is_static_object && descr->is_static_object(addr)) {
			/* Track this static object */
			debug_object_init(addr, descr);
		} else {
			debug_print_object(&o, "assert_init");
			debug_object_fixup(descr->fixup_assert_init, addr,
					   ODEBUG_STATE_NOTAVAILABLE);
		}
		return;
	}

	raw_spin_unlock_irqrestore(&db->lock, flags);
}
EXPORT_SYMBOL_GPL(debug_object_assert_init);

/**
 * debug_object_active_state - debug checks object usage state machine
 * @addr:	address of the object
 * @descr:	pointer to an object specific debug description structure
 * @expect:	expected state
 * @next:	state to move to if expected state is found
 */
void
debug_object_active_state(void *addr, struct debug_obj_descr *descr,
			  unsigned int expect, unsigned int next)
{
	struct debug_bucket *db;
	struct debug_obj *obj;
	unsigned long flags;

	if (!debug_objects_enabled)
		return;

	db = get_bucket((unsigned long) addr);

	raw_spin_lock_irqsave(&db->lock, flags);

	obj = lookup_object(addr, db);
	if (obj) {
		switch (obj->state) {
		case ODEBUG_STATE_ACTIVE:
			if (obj->astate == expect)
				obj->astate = next;
			else
				debug_print_object(obj, "active_state");
			break;

		default:
			debug_print_object(obj, "active_state");
			break;
		}
	} else {
		struct debug_obj o = { .object = addr,
				       .state = ODEBUG_STATE_NOTAVAILABLE,
				       .descr = descr };

		debug_print_object(&o, "active_state");
	}

	raw_spin_unlock_irqrestore(&db->lock, flags);
}
EXPORT_SYMBOL_GPL(debug_object_active_state);

#ifdef CONFIG_DEBUG_OBJECTS_FREE
static void __debug_check_no_obj_freed(const void *address, unsigned long size)
{
	unsigned long flags, oaddr, saddr, eaddr, paddr, chunks;
	struct debug_obj_descr *descr;
	enum debug_obj_state state;
	struct debug_bucket *db;
	struct hlist_node *tmp;
	struct debug_obj *obj;
	int cnt, objs_checked = 0;
	bool work = false;

	saddr = (unsigned long) address;
	eaddr = saddr + size;
	paddr = saddr & ODEBUG_CHUNK_MASK;
	chunks = ((eaddr - paddr) + (ODEBUG_CHUNK_SIZE - 1));
	chunks >>= ODEBUG_CHUNK_SHIFT;

	for (;chunks > 0; chunks--, paddr += ODEBUG_CHUNK_SIZE) {
		db = get_bucket(paddr);

repeat:
		cnt = 0;
		raw_spin_lock_irqsave(&db->lock, flags);
		hlist_for_each_entry_safe(obj, tmp, &db->list, node) {
			cnt++;
			oaddr = (unsigned long) obj->object;
			if (oaddr < saddr || oaddr >= eaddr)
				continue;

			switch (obj->state) {
			case ODEBUG_STATE_ACTIVE:
				debug_print_object(obj, "free");
				descr = obj->descr;
				state = obj->state;
				raw_spin_unlock_irqrestore(&db->lock, flags);
				debug_object_fixup(descr->fixup_free,
						   (void *) oaddr, state);
				goto repeat;
			default:
				hlist_del(&obj->node);
				work |= __free_object(obj);
				break;
			}
		}
		raw_spin_unlock_irqrestore(&db->lock, flags);

		if (cnt > debug_objects_maxchain)
			debug_objects_maxchain = cnt;

		objs_checked += cnt;
	}

	if (objs_checked > debug_objects_maxchecked)
		debug_objects_maxchecked = objs_checked;

	/* Schedule work to actually kmem_cache_free() objects */
	if (work)
		schedule_work(&debug_obj_work);
}

void debug_check_no_obj_freed(const void *address, unsigned long size)
{
	if (debug_objects_enabled)
		__debug_check_no_obj_freed(address, size);
}
#endif

#ifdef CONFIG_DEBUG_FS

static int debug_stats_show(struct seq_file *m, void *v)
{
	seq_printf(m, "max_chain     :%d\n", debug_objects_maxchain);
	seq_printf(m, "max_checked   :%d\n", debug_objects_maxchecked);
	seq_printf(m, "warnings      :%d\n", debug_objects_warnings);
	seq_printf(m, "fixups        :%d\n", debug_objects_fixups);
	seq_printf(m, "pool_free     :%d\n", obj_pool_free);
	seq_printf(m, "pool_min_free :%d\n", obj_pool_min_free);
	seq_printf(m, "pool_used     :%d\n", obj_pool_used);
	seq_printf(m, "pool_max_used :%d\n", obj_pool_max_used);
	seq_printf(m, "on_free_list  :%d\n", obj_nr_tofree);
	seq_printf(m, "objs_allocated:%d\n", debug_objects_allocated);
	seq_printf(m, "objs_freed    :%d\n", debug_objects_freed);
	return 0;
}

static int debug_stats_open(struct inode *inode, struct file *filp)
{
	return single_open(filp, debug_stats_show, NULL);
}

static const struct file_operations debug_stats_fops = {
	.open		= debug_stats_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
};

static int __init debug_objects_init_debugfs(void)
{
	struct dentry *dbgdir, *dbgstats;

	if (!debug_objects_enabled)
		return 0;

	dbgdir = debugfs_create_dir("debug_objects", NULL);
	if (!dbgdir)
		return -ENOMEM;

	dbgstats = debugfs_create_file("stats", 0444, dbgdir, NULL,
				       &debug_stats_fops);
	if (!dbgstats)
		goto err;

	return 0;

err:
	debugfs_remove(dbgdir);

	return -ENOMEM;
}
__initcall(debug_objects_init_debugfs);

#else
static inline void debug_objects_init_debugfs(void) { }
#endif

#ifdef CONFIG_DEBUG_OBJECTS_SELFTEST

/* Random data structure for the self test */
struct self_test {
	unsigned long	dummy1[6];
	int		static_init;
	unsigned long	dummy2[3];
};

static __initdata struct debug_obj_descr descr_type_test;

static bool __init is_static_object(void *addr)
{
	struct self_test *obj = addr;

	return obj->static_init;
}

/*
 * fixup_init is called when:
 * - an active object is initialized
 */
static bool __init fixup_init(void *addr, enum debug_obj_state state)
{
	struct self_test *obj = addr;

	switch (state) {
	case ODEBUG_STATE_ACTIVE:
		debug_object_deactivate(obj, &descr_type_test);
		debug_object_init(obj, &descr_type_test);
		return true;
	default:
		return false;
	}
}

/*
 * fixup_activate is called when:
 * - an active object is activated
 * - an unknown non-static object is activated
 */
static bool __init fixup_activate(void *addr, enum debug_obj_state state)
{
	struct self_test *obj = addr;

	switch (state) {
	case ODEBUG_STATE_NOTAVAILABLE:
		return true;
	case ODEBUG_STATE_ACTIVE:
		debug_object_deactivate(obj, &descr_type_test);
		debug_object_activate(obj, &descr_type_test);
		return true;

	default:
		return false;
	}
}

/*
 * fixup_destroy is called when:
 * - an active object is destroyed
 */
static bool __init fixup_destroy(void *addr, enum debug_obj_state state)
{
	struct self_test *obj = addr;

	switch (state) {
	case ODEBUG_STATE_ACTIVE:
		debug_object_deactivate(obj, &descr_type_test);
		debug_object_destroy(obj, &descr_type_test);
		return true;
	default:
		return false;
	}
}

/*
 * fixup_free is called when:
 * - an active object is freed
 */
static bool __init fixup_free(void *addr, enum debug_obj_state state)
{
	struct self_test *obj = addr;

	switch (state) {
	case ODEBUG_STATE_ACTIVE:
		debug_object_deactivate(obj, &descr_type_test);
		debug_object_free(obj, &descr_type_test);
		return true;
	default:
		return false;
	}
}

static int __init
check_results(void *addr, enum debug_obj_state state, int fixups, int warnings)
{
	struct debug_bucket *db;
	struct debug_obj *obj;
	unsigned long flags;
	int res = -EINVAL;

	db = get_bucket((unsigned long) addr);

	raw_spin_lock_irqsave(&db->lock, flags);

	obj = lookup_object(addr, db);
	if (!obj && state != ODEBUG_STATE_NONE) {
		WARN(1, KERN_ERR "ODEBUG: selftest object not found\n");
		goto out;
	}
	if (obj && obj->state != state) {
		WARN(1, KERN_ERR "ODEBUG: selftest wrong state: %d != %d\n",
		       obj->state, state);
		goto out;
	}
	if (fixups != debug_objects_fixups) {
		WARN(1, KERN_ERR "ODEBUG: selftest fixups failed %d != %d\n",
		       fixups, debug_objects_fixups);
		goto out;
	}
	if (warnings != debug_objects_warnings) {
		WARN(1, KERN_ERR "ODEBUG: selftest warnings failed %d != %d\n",
		       warnings, debug_objects_warnings);
		goto out;
	}
	res = 0;
out:
	raw_spin_unlock_irqrestore(&db->lock, flags);
	if (res)
		debug_objects_enabled = 0;
	return res;
}

static __initdata struct debug_obj_descr descr_type_test = {
	.name			= "selftest",
	.is_static_object	= is_static_object,
	.fixup_init		= fixup_init,
	.fixup_activate		= fixup_activate,
	.fixup_destroy		= fixup_destroy,
	.fixup_free		= fixup_free,
};

static __initdata struct self_test obj = { .static_init = 0 };

static void __init debug_objects_selftest(void)
{
	int fixups, oldfixups, warnings, oldwarnings;
	unsigned long flags;

	local_irq_save(flags);

	fixups = oldfixups = debug_objects_fixups;
	warnings = oldwarnings = debug_objects_warnings;
	descr_test = &descr_type_test;

	debug_object_init(&obj, &descr_type_test);
	if (check_results(&obj, ODEBUG_STATE_INIT, fixups, warnings))
		goto out;
	debug_object_activate(&obj, &descr_type_test);
	if (check_results(&obj, ODEBUG_STATE_ACTIVE, fixups, warnings))
		goto out;
	debug_object_activate(&obj, &descr_type_test);
	if (check_results(&obj, ODEBUG_STATE_ACTIVE, ++fixups, ++warnings))
		goto out;
	debug_object_deactivate(&obj, &descr_type_test);
	if (check_results(&obj, ODEBUG_STATE_INACTIVE, fixups, warnings))
		goto out;
	debug_object_destroy(&obj, &descr_type_test);
	if (check_results(&obj, ODEBUG_STATE_DESTROYED, fixups, warnings))
		goto out;
	debug_object_init(&obj, &descr_type_test);
	if (check_results(&obj, ODEBUG_STATE_DESTROYED, fixups, ++warnings))
		goto out;
	debug_object_activate(&obj, &descr_type_test);
	if (check_results(&obj, ODEBUG_STATE_DESTROYED, fixups, ++warnings))
		goto out;
	debug_object_deactivate(&obj, &descr_type_test);
	if (check_results(&obj, ODEBUG_STATE_DESTROYED, fixups, ++warnings))
		goto out;
	debug_object_free(&obj, &descr_type_test);
	if (check_results(&obj, ODEBUG_STATE_NONE, fixups, warnings))
		goto out;

	obj.static_init = 1;
	debug_object_activate(&obj, &descr_type_test);
	if (check_results(&obj, ODEBUG_STATE_ACTIVE, fixups, warnings))
		goto out;
	debug_object_init(&obj, &descr_type_test);
	if (check_results(&obj, ODEBUG_STATE_INIT, ++fixups, ++warnings))
		goto out;
	debug_object_free(&obj, &descr_type_test);
	if (check_results(&obj, ODEBUG_STATE_NONE, fixups, warnings))
		goto out;

#ifdef CONFIG_DEBUG_OBJECTS_FREE
	debug_object_init(&obj, &descr_type_test);
	if (check_results(&obj, ODEBUG_STATE_INIT, fixups, warnings))
		goto out;
	debug_object_activate(&obj, &descr_type_test);
	if (check_results(&obj, ODEBUG_STATE_ACTIVE, fixups, warnings))
		goto out;
	__debug_check_no_obj_freed(&obj, sizeof(obj));
	if (check_results(&obj, ODEBUG_STATE_NONE, ++fixups, ++warnings))
		goto out;
#endif
	pr_info("selftest passed\n");

out:
	debug_objects_fixups = oldfixups;
	debug_objects_warnings = oldwarnings;
	descr_test = NULL;

	local_irq_restore(flags);
}
#else
static inline void debug_objects_selftest(void) { }
#endif

/*
 * Called during early boot to initialize the hash buckets and link
 * the static object pool objects into the poll list. After this call
 * the object tracker is fully operational.
 */
void __init debug_objects_early_init(void)
{
	int i;

	for (i = 0; i < ODEBUG_HASH_SIZE; i++)
		raw_spin_lock_init(&obj_hash[i].lock);

	for (i = 0; i < ODEBUG_POOL_SIZE; i++)
		hlist_add_head(&obj_static_pool[i].node, &obj_pool);
}

/*
 * Convert the statically allocated objects to dynamic ones:
 */
static int __init debug_objects_replace_static_objects(void)
{
	struct debug_bucket *db = obj_hash;
	struct hlist_node *tmp;
	struct debug_obj *obj, *new;
	HLIST_HEAD(objects);
	int i, cnt = 0;

	for (i = 0; i < ODEBUG_POOL_SIZE; i++) {
		obj = kmem_cache_zalloc(obj_cache, GFP_KERNEL);
		if (!obj)
			goto free;
		hlist_add_head(&obj->node, &objects);
	}

	/*
	 * When debug_objects_mem_init() is called we know that only
	 * one CPU is up, so disabling interrupts is enough
	 * protection. This avoids the lockdep hell of lock ordering.
	 */
	local_irq_disable();

	/* Remove the statically allocated objects from the pool */
	hlist_for_each_entry_safe(obj, tmp, &obj_pool, node)
		hlist_del(&obj->node);
	/* Move the allocated objects to the pool */
	hlist_move_list(&objects, &obj_pool);

	/* Replace the active object references */
	for (i = 0; i < ODEBUG_HASH_SIZE; i++, db++) {
		hlist_move_list(&db->list, &objects);

		hlist_for_each_entry(obj, &objects, node) {
			new = hlist_entry(obj_pool.first, typeof(*obj), node);
			hlist_del(&new->node);
			/* copy object data */
			*new = *obj;
			hlist_add_head(&new->node, &db->list);
			cnt++;
		}
	}
	local_irq_enable();

	pr_debug("%d of %d active objects replaced\n",
		 cnt, obj_pool_used);
	return 0;
free:
	hlist_for_each_entry_safe(obj, tmp, &objects, node) {
		hlist_del(&obj->node);
		kmem_cache_free(obj_cache, obj);
	}
	return -ENOMEM;
}

/*
 * Called after the kmem_caches are functional to setup a dedicated
 * cache pool, which has the SLAB_DEBUG_OBJECTS flag set. This flag
 * prevents that the debug code is called on kmem_cache_free() for the
 * debug tracker objects to avoid recursive calls.
 */
void __init debug_objects_mem_init(void)
{
	if (!debug_objects_enabled)
		return;

	obj_cache = kmem_cache_create("debug_objects_cache",
				      sizeof (struct debug_obj), 0,
				      SLAB_DEBUG_OBJECTS | SLAB_NOLEAKTRACE,
				      NULL);

	if (!obj_cache || debug_objects_replace_static_objects()) {
		debug_objects_enabled = 0;
		kmem_cache_destroy(obj_cache);
		pr_warn("out of memory.\n");
	} else
		debug_objects_selftest();

	/*
	 * Increase the thresholds for allocating and freeing objects
	 * according to the number of possible CPUs available in the system.
	 */
	debug_objects_pool_size += num_possible_cpus() * 32;
	debug_objects_pool_min_level += num_possible_cpus() * 4;
}