summaryrefslogtreecommitdiffstats
path: root/lib/bitmap.c
blob: 730969c681cbaf6228e5f8a78bd56e3e547b7122 (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
/*
 * lib/bitmap.c
 * Helper functions for bitmap.h.
 *
 * This source code is licensed under the GNU General Public License,
 * Version 2.  See the file COPYING for more details.
 */
#include <linux/export.h>
#include <linux/thread_info.h>
#include <linux/ctype.h>
#include <linux/errno.h>
#include <linux/bitmap.h>
#include <linux/bitops.h>
#include <linux/bug.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/uaccess.h>

#include <asm/page.h>

/**
 * DOC: bitmap introduction
 *
 * bitmaps provide an array of bits, implemented using an an
 * array of unsigned longs.  The number of valid bits in a
 * given bitmap does _not_ need to be an exact multiple of
 * BITS_PER_LONG.
 *
 * The possible unused bits in the last, partially used word
 * of a bitmap are 'don't care'.  The implementation makes
 * no particular effort to keep them zero.  It ensures that
 * their value will not affect the results of any operation.
 * The bitmap operations that return Boolean (bitmap_empty,
 * for example) or scalar (bitmap_weight, for example) results
 * carefully filter out these unused bits from impacting their
 * results.
 *
 * These operations actually hold to a slightly stronger rule:
 * if you don't input any bitmaps to these ops that have some
 * unused bits set, then they won't output any set unused bits
 * in output bitmaps.
 *
 * The byte ordering of bitmaps is more natural on little
 * endian architectures.  See the big-endian headers
 * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h
 * for the best explanations of this ordering.
 */

int __bitmap_equal(const unsigned long *bitmap1,
		const unsigned long *bitmap2, unsigned int bits)
{
	unsigned int k, lim = bits/BITS_PER_LONG;
	for (k = 0; k < lim; ++k)
		if (bitmap1[k] != bitmap2[k])
			return 0;

	if (bits % BITS_PER_LONG)
		if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
			return 0;

	return 1;
}
EXPORT_SYMBOL(__bitmap_equal);

void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int bits)
{
	unsigned int k, lim = BITS_TO_LONGS(bits);
	for (k = 0; k < lim; ++k)
		dst[k] = ~src[k];
}
EXPORT_SYMBOL(__bitmap_complement);

/**
 * __bitmap_shift_right - logical right shift of the bits in a bitmap
 *   @dst : destination bitmap
 *   @src : source bitmap
 *   @shift : shift by this many bits
 *   @nbits : bitmap size, in bits
 *
 * Shifting right (dividing) means moving bits in the MS -> LS bit
 * direction.  Zeros are fed into the vacated MS positions and the
 * LS bits shifted off the bottom are lost.
 */
void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
			unsigned shift, unsigned nbits)
{
	unsigned k, lim = BITS_TO_LONGS(nbits);
	unsigned off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
	unsigned long mask = BITMAP_LAST_WORD_MASK(nbits);
	for (k = 0; off + k < lim; ++k) {
		unsigned long upper, lower;

		/*
		 * If shift is not word aligned, take lower rem bits of
		 * word above and make them the top rem bits of result.
		 */
		if (!rem || off + k + 1 >= lim)
			upper = 0;
		else {
			upper = src[off + k + 1];
			if (off + k + 1 == lim - 1)
				upper &= mask;
			upper <<= (BITS_PER_LONG - rem);
		}
		lower = src[off + k];
		if (off + k == lim - 1)
			lower &= mask;
		lower >>= rem;
		dst[k] = lower | upper;
	}
	if (off)
		memset(&dst[lim - off], 0, off*sizeof(unsigned long));
}
EXPORT_SYMBOL(__bitmap_shift_right);


/**
 * __bitmap_shift_left - logical left shift of the bits in a bitmap
 *   @dst : destination bitmap
 *   @src : source bitmap
 *   @shift : shift by this many bits
 *   @nbits : bitmap size, in bits
 *
 * Shifting left (multiplying) means moving bits in the LS -> MS
 * direction.  Zeros are fed into the vacated LS bit positions
 * and those MS bits shifted off the top are lost.
 */

void __bitmap_shift_left(unsigned long *dst, const unsigned long *src,
			unsigned int shift, unsigned int nbits)
{
	int k;
	unsigned int lim = BITS_TO_LONGS(nbits);
	unsigned int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
	for (k = lim - off - 1; k >= 0; --k) {
		unsigned long upper, lower;

		/*
		 * If shift is not word aligned, take upper rem bits of
		 * word below and make them the bottom rem bits of result.
		 */
		if (rem && k > 0)
			lower = src[k - 1] >> (BITS_PER_LONG - rem);
		else
			lower = 0;
		upper = src[k] << rem;
		dst[k + off] = lower | upper;
	}
	if (off)
		memset(dst, 0, off*sizeof(unsigned long));
}
EXPORT_SYMBOL(__bitmap_shift_left);

int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
				const unsigned long *bitmap2, unsigned int bits)
{
	unsigned int k;
	unsigned int lim = bits/BITS_PER_LONG;
	unsigned long result = 0;

	for (k = 0; k < lim; k++)
		result |= (dst[k] = bitmap1[k] & bitmap2[k]);
	if (bits % BITS_PER_LONG)
		result |= (dst[k] = bitmap1[k] & bitmap2[k] &
			   BITMAP_LAST_WORD_MASK(bits));
	return result != 0;
}
EXPORT_SYMBOL(__bitmap_and);

void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
				const unsigned long *bitmap2, unsigned int bits)
{
	unsigned int k;
	unsigned int nr = BITS_TO_LONGS(bits);

	for (k = 0; k < nr; k++)
		dst[k] = bitmap1[k] | bitmap2[k];
}
EXPORT_SYMBOL(__bitmap_or);

void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
				const unsigned long *bitmap2, unsigned int bits)
{
	unsigned int k;
	unsigned int nr = BITS_TO_LONGS(bits);

	for (k = 0; k < nr; k++)
		dst[k] = bitmap1[k] ^ bitmap2[k];
}
EXPORT_SYMBOL(__bitmap_xor);

int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
				const unsigned long *bitmap2, unsigned int bits)
{
	unsigned int k;
	unsigned int lim = bits/BITS_PER_LONG;
	unsigned long result = 0;

	for (k = 0; k < lim; k++)
		result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
	if (bits % BITS_PER_LONG)
		result |= (dst[k] = bitmap1[k] & ~bitmap2[k] &
			   BITMAP_LAST_WORD_MASK(bits));
	return result != 0;
}
EXPORT_SYMBOL(__bitmap_andnot);

int __bitmap_intersects(const unsigned long *bitmap1,
			const unsigned long *bitmap2, unsigned int bits)
{
	unsigned int k, lim = bits/BITS_PER_LONG;
	for (k = 0; k < lim; ++k)
		if (bitmap1[k] & bitmap2[k])
			return 1;

	if (bits % BITS_PER_LONG)
		if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
			return 1;
	return 0;
}
EXPORT_SYMBOL(__bitmap_intersects);

int __bitmap_subset(const unsigned long *bitmap1,
		    const unsigned long *bitmap2, unsigned int bits)
{
	unsigned int k, lim = bits/BITS_PER_LONG;
	for (k = 0; k < lim; ++k)
		if (bitmap1[k] & ~bitmap2[k])
			return 0;

	if (bits % BITS_PER_LONG)
		if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
			return 0;
	return 1;
}
EXPORT_SYMBOL(__bitmap_subset);

int __bitmap_weight(const unsigned long *bitmap, unsigned int bits)
{
	unsigned int k, lim = bits/BITS_PER_LONG;
	int w = 0;

	for (k = 0; k < lim; k++)
		w += hweight_long(bitmap[k]);

	if (bits % BITS_PER_LONG)
		w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));

	return w;
}
EXPORT_SYMBOL(__bitmap_weight);

void __bitmap_set(unsigned long *map, unsigned int start, int len)
{
	unsigned long *p = map + BIT_WORD(start);
	const unsigned int size = start + len;
	int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
	unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);

	while (len - bits_to_set >= 0) {
		*p |= mask_to_set;
		len -= bits_to_set;
		bits_to_set = BITS_PER_LONG;
		mask_to_set = ~0UL;
		p++;
	}
	if (len) {
		mask_to_set &= BITMAP_LAST_WORD_MASK(size);
		*p |= mask_to_set;
	}
}
EXPORT_SYMBOL(__bitmap_set);

void __bitmap_clear(unsigned long *map, unsigned int start, int len)
{
	unsigned long *p = map + BIT_WORD(start);
	const unsigned int size = start + len;
	int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
	unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);

	while (len - bits_to_clear >= 0) {
		*p &= ~mask_to_clear;
		len -= bits_to_clear;
		bits_to_clear = BITS_PER_LONG;
		mask_to_clear = ~0UL;
		p++;
	}
	if (len) {
		mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
		*p &= ~mask_to_clear;
	}
}
EXPORT_SYMBOL(__bitmap_clear);

/**
 * bitmap_find_next_zero_area_off - find a contiguous aligned zero area
 * @map: The address to base the search on
 * @size: The bitmap size in bits
 * @start: The bitnumber to start searching at
 * @nr: The number of zeroed bits we're looking for
 * @align_mask: Alignment mask for zero area
 * @align_offset: Alignment offset for zero area.
 *
 * The @align_mask should be one less than a power of 2; the effect is that
 * the bit offset of all zero areas this function finds plus @align_offset
 * is multiple of that power of 2.
 */
unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
					     unsigned long size,
					     unsigned long start,
					     unsigned int nr,
					     unsigned long align_mask,
					     unsigned long align_offset)
{
	unsigned long index, end, i;
again:
	index = find_next_zero_bit(map, size, start);

	/* Align allocation */
	index = __ALIGN_MASK(index + align_offset, align_mask) - align_offset;

	end = index + nr;
	if (end > size)
		return end;
	i = find_next_bit(map, end, index);
	if (i < end) {
		start = i + 1;
		goto again;
	}
	return index;
}
EXPORT_SYMBOL(bitmap_find_next_zero_area_off);

/*
 * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers,
 * second version by Paul Jackson, third by Joe Korty.
 */

#define CHUNKSZ				32
#define nbits_to_hold_value(val)	fls(val)
#define BASEDEC 10		/* fancier cpuset lists input in decimal */

/**
 * __bitmap_parse - convert an ASCII hex string into a bitmap.
 * @buf: pointer to buffer containing string.
 * @buflen: buffer size in bytes.  If string is smaller than this
 *    then it must be terminated with a \0.
 * @is_user: location of buffer, 0 indicates kernel space
 * @maskp: pointer to bitmap array that will contain result.
 * @nmaskbits: size of bitmap, in bits.
 *
 * Commas group hex digits into chunks.  Each chunk defines exactly 32
 * bits of the resultant bitmask.  No chunk may specify a value larger
 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
 * then leading 0-bits are prepended.  %-EINVAL is returned for illegal
 * characters and for grouping errors such as "1,,5", ",44", "," and "".
 * Leading and trailing whitespace accepted, but not embedded whitespace.
 */
int __bitmap_parse(const char *buf, unsigned int buflen,
		int is_user, unsigned long *maskp,
		int nmaskbits)
{
	int c, old_c, totaldigits, ndigits, nchunks, nbits;
	u32 chunk;
	const char __user __force *ubuf = (const char __user __force *)buf;

	bitmap_zero(maskp, nmaskbits);

	nchunks = nbits = totaldigits = c = 0;
	do {
		chunk = 0;
		ndigits = totaldigits;

		/* Get the next chunk of the bitmap */
		while (buflen) {
			old_c = c;
			if (is_user) {
				if (__get_user(c, ubuf++))
					return -EFAULT;
			}
			else
				c = *buf++;
			buflen--;
			if (isspace(c))
				continue;

			/*
			 * If the last character was a space and the current
			 * character isn't '\0', we've got embedded whitespace.
			 * This is a no-no, so throw an error.
			 */
			if (totaldigits && c && isspace(old_c))
				return -EINVAL;

			/* A '\0' or a ',' signal the end of the chunk */
			if (c == '\0' || c == ',')
				break;

			if (!isxdigit(c))
				return -EINVAL;

			/*
			 * Make sure there are at least 4 free bits in 'chunk'.
			 * If not, this hexdigit will overflow 'chunk', so
			 * throw an error.
			 */
			if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
				return -EOVERFLOW;

			chunk = (chunk << 4) | hex_to_bin(c);
			totaldigits++;
		}
		if (ndigits == totaldigits)
			return -EINVAL;
		if (nchunks == 0 && chunk == 0)
			continue;

		__bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
		*maskp |= chunk;
		nchunks++;
		nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
		if (nbits > nmaskbits)
			return -EOVERFLOW;
	} while (buflen && c == ',');

	return 0;
}
EXPORT_SYMBOL(__bitmap_parse);

/**
 * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap
 *
 * @ubuf: pointer to user buffer containing string.
 * @ulen: buffer size in bytes.  If string is smaller than this
 *    then it must be terminated with a \0.
 * @maskp: pointer to bitmap array that will contain result.
 * @nmaskbits: size of bitmap, in bits.
 *
 * Wrapper for __bitmap_parse(), providing it with user buffer.
 *
 * We cannot have this as an inline function in bitmap.h because it needs
 * linux/uaccess.h to get the access_ok() declaration and this causes
 * cyclic dependencies.
 */
int bitmap_parse_user(const char __user *ubuf,
			unsigned int ulen, unsigned long *maskp,
			int nmaskbits)
{
	if (!access_ok(VERIFY_READ, ubuf, ulen))
		return -EFAULT;
	return __bitmap_parse((const char __force *)ubuf,
				ulen, 1, maskp, nmaskbits);

}
EXPORT_SYMBOL(bitmap_parse_user);

/**
 * bitmap_print_to_pagebuf - convert bitmap to list or hex format ASCII string
 * @list: indicates whether the bitmap must be list
 * @buf: page aligned buffer into which string is placed
 * @maskp: pointer to bitmap to convert
 * @nmaskbits: size of bitmap, in bits
 *
 * Output format is a comma-separated list of decimal numbers and
 * ranges if list is specified or hex digits grouped into comma-separated
 * sets of 8 digits/set. Returns the number of characters written to buf.
 *
 * It is assumed that @buf is a pointer into a PAGE_SIZE area and that
 * sufficient storage remains at @buf to accommodate the
 * bitmap_print_to_pagebuf() output.
 */
int bitmap_print_to_pagebuf(bool list, char *buf, const unsigned long *maskp,
			    int nmaskbits)
{
	ptrdiff_t len = PTR_ALIGN(buf + PAGE_SIZE - 1, PAGE_SIZE) - buf;
	int n = 0;

	if (len > 1)
		n = list ? scnprintf(buf, len, "%*pbl\n", nmaskbits, maskp) :
			   scnprintf(buf, len, "%*pb\n", nmaskbits, maskp);
	return n;
}
EXPORT_SYMBOL(bitmap_print_to_pagebuf);

/**
 * __bitmap_parselist - convert list format ASCII string to bitmap
 * @buf: read nul-terminated user string from this buffer
 * @buflen: buffer size in bytes.  If string is smaller than this
 *    then it must be terminated with a \0.
 * @is_user: location of buffer, 0 indicates kernel space
 * @maskp: write resulting mask here
 * @nmaskbits: number of bits in mask to be written
 *
 * Input format is a comma-separated list of decimal numbers and
 * ranges.  Consecutively set bits are shown as two hyphen-separated
 * decimal numbers, the smallest and largest bit numbers set in
 * the range.
 * Optionally each range can be postfixed to denote that only parts of it
 * should be set. The range will divided to groups of specific size.
 * From each group will be used only defined amount of bits.
 * Syntax: range:used_size/group_size
 * Example: 0-1023:2/256 ==> 0,1,256,257,512,513,768,769
 *
 * Returns: 0 on success, -errno on invalid input strings. Error values:
 *
 *   - ``-EINVAL``: second number in range smaller than first
 *   - ``-EINVAL``: invalid character in string
 *   - ``-ERANGE``: bit number specified too large for mask
 */
static int __bitmap_parselist(const char *buf, unsigned int buflen,
		int is_user, unsigned long *maskp,
		int nmaskbits)
{
	unsigned int a, b, old_a, old_b;
	unsigned int group_size, used_size, off;
	int c, old_c, totaldigits, ndigits;
	const char __user __force *ubuf = (const char __user __force *)buf;
	int at_start, in_range, in_partial_range;

	totaldigits = c = 0;
	old_a = old_b = 0;
	group_size = used_size = 0;
	bitmap_zero(maskp, nmaskbits);
	do {
		at_start = 1;
		in_range = 0;
		in_partial_range = 0;
		a = b = 0;
		ndigits = totaldigits;

		/* Get the next cpu# or a range of cpu#'s */
		while (buflen) {
			old_c = c;
			if (is_user) {
				if (__get_user(c, ubuf++))
					return -EFAULT;
			} else
				c = *buf++;
			buflen--;
			if (isspace(c))
				continue;

			/* A '\0' or a ',' signal the end of a cpu# or range */
			if (c == '\0' || c == ',')
				break;
			/*
			* whitespaces between digits are not allowed,
			* but it's ok if whitespaces are on head or tail.
			* when old_c is whilespace,
			* if totaldigits == ndigits, whitespace is on head.
			* if whitespace is on tail, it should not run here.
			* as c was ',' or '\0',
			* the last code line has broken the current loop.
			*/
			if ((totaldigits != ndigits) && isspace(old_c))
				return -EINVAL;

			if (c == '/') {
				used_size = a;
				at_start = 1;
				in_range = 0;
				a = b = 0;
				continue;
			}

			if (c == ':') {
				old_a = a;
				old_b = b;
				at_start = 1;
				in_range = 0;
				in_partial_range = 1;
				a = b = 0;
				continue;
			}

			if (c == '-') {
				if (at_start || in_range)
					return -EINVAL;
				b = 0;
				in_range = 1;
				at_start = 1;
				continue;
			}

			if (!isdigit(c))
				return -EINVAL;

			b = b * 10 + (c - '0');
			if (!in_range)
				a = b;
			at_start = 0;
			totaldigits++;
		}
		if (ndigits == totaldigits)
			continue;
		if (in_partial_range) {
			group_size = a;
			a = old_a;
			b = old_b;
			old_a = old_b = 0;
		} else {
			used_size = group_size = b - a + 1;
		}
		/* if no digit is after '-', it's wrong*/
		if (at_start && in_range)
			return -EINVAL;
		if (!(a <= b) || group_size == 0 || !(used_size <= group_size))
			return -EINVAL;
		if (b >= nmaskbits)
			return -ERANGE;
		while (a <= b) {
			off = min(b - a + 1, used_size);
			bitmap_set(maskp, a, off);
			a += group_size;
		}
	} while (buflen && c == ',');
	return 0;
}

int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
{
	char *nl  = strchrnul(bp, '\n');
	int len = nl - bp;

	return __bitmap_parselist(bp, len, 0, maskp, nmaskbits);
}
EXPORT_SYMBOL(bitmap_parselist);


/**
 * bitmap_parselist_user()
 *
 * @ubuf: pointer to user buffer containing string.
 * @ulen: buffer size in bytes.  If string is smaller than this
 *    then it must be terminated with a \0.
 * @maskp: pointer to bitmap array that will contain result.
 * @nmaskbits: size of bitmap, in bits.
 *
 * Wrapper for bitmap_parselist(), providing it with user buffer.
 *
 * We cannot have this as an inline function in bitmap.h because it needs
 * linux/uaccess.h to get the access_ok() declaration and this causes
 * cyclic dependencies.
 */
int bitmap_parselist_user(const char __user *ubuf,
			unsigned int ulen, unsigned long *maskp,
			int nmaskbits)
{
	if (!access_ok(VERIFY_READ, ubuf, ulen))
		return -EFAULT;
	return __bitmap_parselist((const char __force *)ubuf,
					ulen, 1, maskp, nmaskbits);
}
EXPORT_SYMBOL(bitmap_parselist_user);


/**
 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
 *	@buf: pointer to a bitmap
 *	@pos: a bit position in @buf (0 <= @pos < @nbits)
 *	@nbits: number of valid bit positions in @buf
 *
 * Map the bit at position @pos in @buf (of length @nbits) to the
 * ordinal of which set bit it is.  If it is not set or if @pos
 * is not a valid bit position, map to -1.
 *
 * If for example, just bits 4 through 7 are set in @buf, then @pos
 * values 4 through 7 will get mapped to 0 through 3, respectively,
 * and other @pos values will get mapped to -1.  When @pos value 7
 * gets mapped to (returns) @ord value 3 in this example, that means
 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
 *
 * The bit positions 0 through @bits are valid positions in @buf.
 */
static int bitmap_pos_to_ord(const unsigned long *buf, unsigned int pos, unsigned int nbits)
{
	if (pos >= nbits || !test_bit(pos, buf))
		return -1;

	return __bitmap_weight(buf, pos);
}

/**
 * bitmap_ord_to_pos - find position of n-th set bit in bitmap
 *	@buf: pointer to bitmap
 *	@ord: ordinal bit position (n-th set bit, n >= 0)
 *	@nbits: number of valid bit positions in @buf
 *
 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
 * Value of @ord should be in range 0 <= @ord < weight(buf). If @ord
 * >= weight(buf), returns @nbits.
 *
 * If for example, just bits 4 through 7 are set in @buf, then @ord
 * values 0 through 3 will get mapped to 4 through 7, respectively,
 * and all other @ord values returns @nbits.  When @ord value 3
 * gets mapped to (returns) @pos value 7 in this example, that means
 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
 *
 * The bit positions 0 through @nbits-1 are valid positions in @buf.
 */
unsigned int bitmap_ord_to_pos(const unsigned long *buf, unsigned int ord, unsigned int nbits)
{
	unsigned int pos;

	for (pos = find_first_bit(buf, nbits);
	     pos < nbits && ord;
	     pos = find_next_bit(buf, nbits, pos + 1))
		ord--;

	return pos;
}

/**
 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
 *	@dst: remapped result
 *	@src: subset to be remapped
 *	@old: defines domain of map
 *	@new: defines range of map
 *	@nbits: number of bits in each of these bitmaps
 *
 * Let @old and @new define a mapping of bit positions, such that
 * whatever position is held by the n-th set bit in @old is mapped
 * to the n-th set bit in @new.  In the more general case, allowing
 * for the possibility that the weight 'w' of @new is less than the
 * weight of @old, map the position of the n-th set bit in @old to
 * the position of the m-th set bit in @new, where m == n % w.
 *
 * If either of the @old and @new bitmaps are empty, or if @src and
 * @dst point to the same location, then this routine copies @src
 * to @dst.
 *
 * The positions of unset bits in @old are mapped to themselves
 * (the identify map).
 *
 * Apply the above specified mapping to @src, placing the result in
 * @dst, clearing any bits previously set in @dst.
 *
 * For example, lets say that @old has bits 4 through 7 set, and
 * @new has bits 12 through 15 set.  This defines the mapping of bit
 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
 * bit positions unchanged.  So if say @src comes into this routine
 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
 * 13 and 15 set.
 */
void bitmap_remap(unsigned long *dst, const unsigned long *src,
		const unsigned long *old, const unsigned long *new,
		unsigned int nbits)
{
	unsigned int oldbit, w;

	if (dst == src)		/* following doesn't handle inplace remaps */
		return;
	bitmap_zero(dst, nbits);

	w = bitmap_weight(new, nbits);
	for_each_set_bit(oldbit, src, nbits) {
		int n = bitmap_pos_to_ord(old, oldbit, nbits);

		if (n < 0 || w == 0)
			set_bit(oldbit, dst);	/* identity map */
		else
			set_bit(bitmap_ord_to_pos(new, n % w, nbits), dst);
	}
}
EXPORT_SYMBOL(bitmap_remap);

/**
 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
 *	@oldbit: bit position to be mapped
 *	@old: defines domain of map
 *	@new: defines range of map
 *	@bits: number of bits in each of these bitmaps
 *
 * Let @old and @new define a mapping of bit positions, such that
 * whatever position is held by the n-th set bit in @old is mapped
 * to the n-th set bit in @new.  In the more general case, allowing
 * for the possibility that the weight 'w' of @new is less than the
 * weight of @old, map the position of the n-th set bit in @old to
 * the position of the m-th set bit in @new, where m == n % w.
 *
 * The positions of unset bits in @old are mapped to themselves
 * (the identify map).
 *
 * Apply the above specified mapping to bit position @oldbit, returning
 * the new bit position.
 *
 * For example, lets say that @old has bits 4 through 7 set, and
 * @new has bits 12 through 15 set.  This defines the mapping of bit
 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
 * bit positions unchanged.  So if say @oldbit is 5, then this routine
 * returns 13.
 */
int bitmap_bitremap(int oldbit, const unsigned long *old,
				const unsigned long *new, int bits)
{
	int w = bitmap_weight(new, bits);
	int n = bitmap_pos_to_ord(old, oldbit, bits);
	if (n < 0 || w == 0)
		return oldbit;
	else
		return bitmap_ord_to_pos(new, n % w, bits);
}
EXPORT_SYMBOL(bitmap_bitremap);

/**
 * bitmap_onto - translate one bitmap relative to another
 *	@dst: resulting translated bitmap
 * 	@orig: original untranslated bitmap
 * 	@relmap: bitmap relative to which translated
 *	@bits: number of bits in each of these bitmaps
 *
 * Set the n-th bit of @dst iff there exists some m such that the
 * n-th bit of @relmap is set, the m-th bit of @orig is set, and
 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
 * (If you understood the previous sentence the first time your
 * read it, you're overqualified for your current job.)
 *
 * In other words, @orig is mapped onto (surjectively) @dst,
 * using the map { <n, m> | the n-th bit of @relmap is the
 * m-th set bit of @relmap }.
 *
 * Any set bits in @orig above bit number W, where W is the
 * weight of (number of set bits in) @relmap are mapped nowhere.
 * In particular, if for all bits m set in @orig, m >= W, then
 * @dst will end up empty.  In situations where the possibility
 * of such an empty result is not desired, one way to avoid it is
 * to use the bitmap_fold() operator, below, to first fold the
 * @orig bitmap over itself so that all its set bits x are in the
 * range 0 <= x < W.  The bitmap_fold() operator does this by
 * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
 *
 * Example [1] for bitmap_onto():
 *  Let's say @relmap has bits 30-39 set, and @orig has bits
 *  1, 3, 5, 7, 9 and 11 set.  Then on return from this routine,
 *  @dst will have bits 31, 33, 35, 37 and 39 set.
 *
 *  When bit 0 is set in @orig, it means turn on the bit in
 *  @dst corresponding to whatever is the first bit (if any)
 *  that is turned on in @relmap.  Since bit 0 was off in the
 *  above example, we leave off that bit (bit 30) in @dst.
 *
 *  When bit 1 is set in @orig (as in the above example), it
 *  means turn on the bit in @dst corresponding to whatever
 *  is the second bit that is turned on in @relmap.  The second
 *  bit in @relmap that was turned on in the above example was
 *  bit 31, so we turned on bit 31 in @dst.
 *
 *  Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
 *  because they were the 4th, 6th, 8th and 10th set bits
 *  set in @relmap, and the 4th, 6th, 8th and 10th bits of
 *  @orig (i.e. bits 3, 5, 7 and 9) were also set.
 *
 *  When bit 11 is set in @orig, it means turn on the bit in
 *  @dst corresponding to whatever is the twelfth bit that is
 *  turned on in @relmap.  In the above example, there were
 *  only ten bits turned on in @relmap (30..39), so that bit
 *  11 was set in @orig had no affect on @dst.
 *
 * Example [2] for bitmap_fold() + bitmap_onto():
 *  Let's say @relmap has these ten bits set::
 *
 *		40 41 42 43 45 48 53 61 74 95
 *
 *  (for the curious, that's 40 plus the first ten terms of the
 *  Fibonacci sequence.)
 *
 *  Further lets say we use the following code, invoking
 *  bitmap_fold() then bitmap_onto, as suggested above to
 *  avoid the possibility of an empty @dst result::
 *
 *	unsigned long *tmp;	// a temporary bitmap's bits
 *
 *	bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
 *	bitmap_onto(dst, tmp, relmap, bits);
 *
 *  Then this table shows what various values of @dst would be, for
 *  various @orig's.  I list the zero-based positions of each set bit.
 *  The tmp column shows the intermediate result, as computed by
 *  using bitmap_fold() to fold the @orig bitmap modulo ten
 *  (the weight of @relmap):
 *
 *      =============== ============== =================
 *      @orig           tmp            @dst
 *      0                0             40
 *      1                1             41
 *      9                9             95
 *      10               0             40 [#f1]_
 *      1 3 5 7          1 3 5 7       41 43 48 61
 *      0 1 2 3 4        0 1 2 3 4     40 41 42 43 45
 *      0 9 18 27        0 9 8 7       40 61 74 95
 *      0 10 20 30       0             40
 *      0 11 22 33       0 1 2 3       40 41 42 43
 *      0 12 24 36       0 2 4 6       40 42 45 53
 *      78 102 211       1 2 8         41 42 74 [#f1]_
 *      =============== ============== =================
 *
 * .. [#f1]
 *
 *     For these marked lines, if we hadn't first done bitmap_fold()
 *     into tmp, then the @dst result would have been empty.
 *
 * If either of @orig or @relmap is empty (no set bits), then @dst
 * will be returned empty.
 *
 * If (as explained above) the only set bits in @orig are in positions
 * m where m >= W, (where W is the weight of @relmap) then @dst will
 * once again be returned empty.
 *
 * All bits in @dst not set by the above rule are cleared.
 */
void bitmap_onto(unsigned long *dst, const unsigned long *orig,
			const unsigned long *relmap, unsigned int bits)
{
	unsigned int n, m;	/* same meaning as in above comment */

	if (dst == orig)	/* following doesn't handle inplace mappings */
		return;
	bitmap_zero(dst, bits);

	/*
	 * The following code is a more efficient, but less
	 * obvious, equivalent to the loop:
	 *	for (m = 0; m < bitmap_weight(relmap, bits); m++) {
	 *		n = bitmap_ord_to_pos(orig, m, bits);
	 *		if (test_bit(m, orig))
	 *			set_bit(n, dst);
	 *	}
	 */

	m = 0;
	for_each_set_bit(n, relmap, bits) {
		/* m == bitmap_pos_to_ord(relmap, n, bits) */
		if (test_bit(m, orig))
			set_bit(n, dst);
		m++;
	}
}
EXPORT_SYMBOL(bitmap_onto);

/**
 * bitmap_fold - fold larger bitmap into smaller, modulo specified size
 *	@dst: resulting smaller bitmap
 *	@orig: original larger bitmap
 *	@sz: specified size
 *	@nbits: number of bits in each of these bitmaps
 *
 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
 * Clear all other bits in @dst.  See further the comment and
 * Example [2] for bitmap_onto() for why and how to use this.
 */
void bitmap_fold(unsigned long *dst, const unsigned long *orig,
			unsigned int sz, unsigned int nbits)
{
	unsigned int oldbit;

	if (dst == orig)	/* following doesn't handle inplace mappings */
		return;
	bitmap_zero(dst, nbits);

	for_each_set_bit(oldbit, orig, nbits)
		set_bit(oldbit % sz, dst);
}
EXPORT_SYMBOL(bitmap_fold);

/*
 * Common code for bitmap_*_region() routines.
 *	bitmap: array of unsigned longs corresponding to the bitmap
 *	pos: the beginning of the region
 *	order: region size (log base 2 of number of bits)
 *	reg_op: operation(s) to perform on that region of bitmap
 *
 * Can set, verify and/or release a region of bits in a bitmap,
 * depending on which combination of REG_OP_* flag bits is set.
 *
 * A region of a bitmap is a sequence of bits in the bitmap, of
 * some size '1 << order' (a power of two), aligned to that same
 * '1 << order' power of two.
 *
 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
 * Returns 0 in all other cases and reg_ops.
 */

enum {
	REG_OP_ISFREE,		/* true if region is all zero bits */
	REG_OP_ALLOC,		/* set all bits in region */
	REG_OP_RELEASE,		/* clear all bits in region */
};

static int __reg_op(unsigned long *bitmap, unsigned int pos, int order, int reg_op)
{
	int nbits_reg;		/* number of bits in region */
	int index;		/* index first long of region in bitmap */
	int offset;		/* bit offset region in bitmap[index] */
	int nlongs_reg;		/* num longs spanned by region in bitmap */
	int nbitsinlong;	/* num bits of region in each spanned long */
	unsigned long mask;	/* bitmask for one long of region */
	int i;			/* scans bitmap by longs */
	int ret = 0;		/* return value */

	/*
	 * Either nlongs_reg == 1 (for small orders that fit in one long)
	 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
	 */
	nbits_reg = 1 << order;
	index = pos / BITS_PER_LONG;
	offset = pos - (index * BITS_PER_LONG);
	nlongs_reg = BITS_TO_LONGS(nbits_reg);
	nbitsinlong = min(nbits_reg,  BITS_PER_LONG);

	/*
	 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
	 * overflows if nbitsinlong == BITS_PER_LONG.
	 */
	mask = (1UL << (nbitsinlong - 1));
	mask += mask - 1;
	mask <<= offset;

	switch (reg_op) {
	case REG_OP_ISFREE:
		for (i = 0; i < nlongs_reg; i++) {
			if (bitmap[index + i] & mask)
				goto done;
		}
		ret = 1;	/* all bits in region free (zero) */
		break;

	case REG_OP_ALLOC:
		for (i = 0; i < nlongs_reg; i++)
			bitmap[index + i] |= mask;
		break;

	case REG_OP_RELEASE:
		for (i = 0; i < nlongs_reg; i++)
			bitmap[index + i] &= ~mask;
		break;
	}
done:
	return ret;
}

/**
 * bitmap_find_free_region - find a contiguous aligned mem region
 *	@bitmap: array of unsigned longs corresponding to the bitmap
 *	@bits: number of bits in the bitmap
 *	@order: region size (log base 2 of number of bits) to find
 *
 * Find a region of free (zero) bits in a @bitmap of @bits bits and
 * allocate them (set them to one).  Only consider regions of length
 * a power (@order) of two, aligned to that power of two, which
 * makes the search algorithm much faster.
 *
 * Return the bit offset in bitmap of the allocated region,
 * or -errno on failure.
 */
int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order)
{
	unsigned int pos, end;		/* scans bitmap by regions of size order */

	for (pos = 0 ; (end = pos + (1U << order)) <= bits; pos = end) {
		if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
			continue;
		__reg_op(bitmap, pos, order, REG_OP_ALLOC);
		return pos;
	}
	return -ENOMEM;
}
EXPORT_SYMBOL(bitmap_find_free_region);

/**
 * bitmap_release_region - release allocated bitmap region
 *	@bitmap: array of unsigned longs corresponding to the bitmap
 *	@pos: beginning of bit region to release
 *	@order: region size (log base 2 of number of bits) to release
 *
 * This is the complement to __bitmap_find_free_region() and releases
 * the found region (by clearing it in the bitmap).
 *
 * No return value.
 */
void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order)
{
	__reg_op(bitmap, pos, order, REG_OP_RELEASE);
}
EXPORT_SYMBOL(bitmap_release_region);

/**
 * bitmap_allocate_region - allocate bitmap region
 *	@bitmap: array of unsigned longs corresponding to the bitmap
 *	@pos: beginning of bit region to allocate
 *	@order: region size (log base 2 of number of bits) to allocate
 *
 * Allocate (set bits in) a specified region of a bitmap.
 *
 * Return 0 on success, or %-EBUSY if specified region wasn't
 * free (not all bits were zero).
 */
int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order)
{
	if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
		return -EBUSY;
	return __reg_op(bitmap, pos, order, REG_OP_ALLOC);
}
EXPORT_SYMBOL(bitmap_allocate_region);

/**
 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
 * @dst:   destination buffer
 * @src:   bitmap to copy
 * @nbits: number of bits in the bitmap
 *
 * Require nbits % BITS_PER_LONG == 0.
 */
#ifdef __BIG_ENDIAN
void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int nbits)
{
	unsigned int i;

	for (i = 0; i < nbits/BITS_PER_LONG; i++) {
		if (BITS_PER_LONG == 64)
			dst[i] = cpu_to_le64(src[i]);
		else
			dst[i] = cpu_to_le32(src[i]);
	}
}
EXPORT_SYMBOL(bitmap_copy_le);
#endif

unsigned long *bitmap_alloc(unsigned int nbits, gfp_t flags)
{
	return kmalloc_array(BITS_TO_LONGS(nbits), sizeof(unsigned long),
			     flags);
}
EXPORT_SYMBOL(bitmap_alloc);

unsigned long *bitmap_zalloc(unsigned int nbits, gfp_t flags)
{
	return bitmap_alloc(nbits, flags | __GFP_ZERO);
}
EXPORT_SYMBOL(bitmap_zalloc);

void bitmap_free(const unsigned long *bitmap)
{
	kfree(bitmap);
}
EXPORT_SYMBOL(bitmap_free);

#if BITS_PER_LONG == 64
/**
 * bitmap_from_arr32 - copy the contents of u32 array of bits to bitmap
 *	@bitmap: array of unsigned longs, the destination bitmap
 *	@buf: array of u32 (in host byte order), the source bitmap
 *	@nbits: number of bits in @bitmap
 */
void bitmap_from_arr32(unsigned long *bitmap, const u32 *buf,
						unsigned int nbits)
{
	unsigned int i, halfwords;

	if (!nbits)
		return;

	halfwords = DIV_ROUND_UP(nbits, 32);
	for (i = 0; i < halfwords; i++) {
		bitmap[i/2] = (unsigned long) buf[i];
		if (++i < halfwords)
			bitmap[i/2] |= ((unsigned long) buf[i]) << 32;
	}

	/* Clear tail bits in last word beyond nbits. */
	if (nbits % BITS_PER_LONG)
		bitmap[(halfwords - 1) / 2] &= BITMAP_LAST_WORD_MASK(nbits);
}
EXPORT_SYMBOL(bitmap_from_arr32);

/**
 * bitmap_to_arr32 - copy the contents of bitmap to a u32 array of bits
 *	@buf: array of u32 (in host byte order), the dest bitmap
 *	@bitmap: array of unsigned longs, the source bitmap
 *	@nbits: number of bits in @bitmap
 */
void bitmap_to_arr32(u32 *buf, const unsigned long *bitmap, unsigned int nbits)
{
	unsigned int i, halfwords;

	if (!nbits)
		return;

	halfwords = DIV_ROUND_UP(nbits, 32);
	for (i = 0; i < halfwords; i++) {
		buf[i] = (u32) (bitmap[i/2] & UINT_MAX);
		if (++i < halfwords)
			buf[i] = (u32) (bitmap[i/2] >> 32);
	}

	/* Clear tail bits in last element of array beyond nbits. */
	if (nbits % BITS_PER_LONG)
		buf[halfwords - 1] &= (u32) (UINT_MAX >> ((-nbits) & 31));
}
EXPORT_SYMBOL(bitmap_to_arr32);

#endif