aboutsummaryrefslogtreecommitdiff
path: root/kernel/params.c
blob: b6554aa71094473094a97010ec4e3f739f92b5c8 (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
/* Helpers for initial module or kernel cmdline parsing
   Copyright (C) 2001 Rusty Russell.

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/ctype.h>

#ifdef CONFIG_SYSFS
/* Protects all built-in parameters, modules use their own param_lock */
static DEFINE_MUTEX(param_lock);

/* Use the module's mutex, or if built-in use the built-in mutex */
#ifdef CONFIG_MODULES
#define KPARAM_MUTEX(mod)	((mod) ? &(mod)->param_lock : &param_lock)
#else
#define KPARAM_MUTEX(mod)	(&param_lock)
#endif

static inline void check_kparam_locked(struct module *mod)
{
	BUG_ON(!mutex_is_locked(KPARAM_MUTEX(mod)));
}
#else
static inline void check_kparam_locked(struct module *mod)
{
}
#endif /* !CONFIG_SYSFS */

/* This just allows us to keep track of which parameters are kmalloced. */
struct kmalloced_param {
	struct list_head list;
	char val[];
};
static LIST_HEAD(kmalloced_params);
static DEFINE_SPINLOCK(kmalloced_params_lock);

static void *kmalloc_parameter(unsigned int size)
{
	struct kmalloced_param *p;

	p = kmalloc(sizeof(*p) + size, GFP_KERNEL);
	if (!p)
		return NULL;

	spin_lock(&kmalloced_params_lock);
	list_add(&p->list, &kmalloced_params);
	spin_unlock(&kmalloced_params_lock);

	return p->val;
}

/* Does nothing if parameter wasn't kmalloced above. */
static void maybe_kfree_parameter(void *param)
{
	struct kmalloced_param *p;

	spin_lock(&kmalloced_params_lock);
	list_for_each_entry(p, &kmalloced_params, list) {
		if (p->val == param) {
			list_del(&p->list);
			kfree(p);
			break;
		}
	}
	spin_unlock(&kmalloced_params_lock);
}

static char dash2underscore(char c)
{
	if (c == '-')
		return '_';
	return c;
}

bool parameqn(const char *a, const char *b, size_t n)
{
	size_t i;

	for (i = 0; i < n; i++) {
		if (dash2underscore(a[i]) != dash2underscore(b[i]))
			return false;
	}
	return true;
}

bool parameq(const char *a, const char *b)
{
	return parameqn(a, b, strlen(a)+1);
}

static void param_check_unsafe(const struct kernel_param *kp)
{
	if (kp->flags & KERNEL_PARAM_FL_UNSAFE) {
		pr_warn("Setting dangerous option %s - tainting kernel\n",
			kp->name);
		add_taint(TAINT_USER, LOCKDEP_STILL_OK);
	}
}

static int parse_one(char *param,
		     char *val,
		     const char *doing,
		     const struct kernel_param *params,
		     unsigned num_params,
		     s16 min_level,
		     s16 max_level,
		     void *arg,
		     int (*handle_unknown)(char *param, char *val,
				     const char *doing, void *arg))
{
	unsigned int i;
	int err;

	/* Find parameter */
	for (i = 0; i < num_params; i++) {
		if (parameq(param, params[i].name)) {
			if (params[i].level < min_level
			    || params[i].level > max_level)
				return 0;
			/* No one handled NULL, so do it here. */
			if (!val &&
			    !(params[i].ops->flags & KERNEL_PARAM_OPS_FL_NOARG))
				return -EINVAL;
			pr_debug("handling %s with %p\n", param,
				params[i].ops->set);
			kernel_param_lock(params[i].mod);
			param_check_unsafe(&params[i]);
			err = params[i].ops->set(val, &params[i]);
			kernel_param_unlock(params[i].mod);
			return err;
		}
	}

	if (handle_unknown) {
		pr_debug("doing %s: %s='%s'\n", doing, param, val);
		return handle_unknown(param, val, doing, arg);
	}

	pr_debug("Unknown argument '%s'\n", param);
	return -ENOENT;
}

/* You can use " around spaces, but can't escape ". */
/* Hyphens and underscores equivalent in parameter names. */
static char *next_arg(char *args, char **param, char **val)
{
	unsigned int i, equals = 0;
	int in_quote = 0, quoted = 0;
	char *next;

	if (*args == '"') {
		args++;
		in_quote = 1;
		quoted = 1;
	}

	for (i = 0; args[i]; i++) {
		if (isspace(args[i]) && !in_quote)
			break;
		if (equals == 0) {
			if (args[i] == '=')
				equals = i;
		}
		if (args[i] == '"')
			in_quote = !in_quote;
	}

	*param = args;
	if (!equals)
		*val = NULL;
	else {
		args[equals] = '\0';
		*val = args + equals + 1;

		/* Don't include quotes in value. */
		if (**val == '"') {
			(*val)++;
			if (args[i-1] == '"')
				args[i-1] = '\0';
		}
	}
	if (quoted && args[i-1] == '"')
		args[i-1] = '\0';

	if (args[i]) {
		args[i] = '\0';
		next = args + i + 1;
	} else
		next = args + i;

	/* Chew up trailing spaces. */
	return skip_spaces(next);
}

/* Args looks like "foo=bar,bar2 baz=fuz wiz". */
char *parse_args(const char *doing,
		 char *args,
		 const struct kernel_param *params,
		 unsigned num,
		 s16 min_level,
		 s16 max_level,
		 void *arg,
		 int (*unknown)(char *param, char *val,
				const char *doing, void *arg))
{
	char *param, *val;

	/* Chew leading spaces */
	args = skip_spaces(args);

	if (*args)
		pr_debug("doing %s, parsing ARGS: '%s'\n", doing, args);

	while (*args) {
		int ret;
		int irq_was_disabled;

		args = next_arg(args, &param, &val);
		/* Stop at -- */
		if (!val && strcmp(param, "--") == 0)
			return args;
		irq_was_disabled = irqs_disabled();
		ret = parse_one(param, val, doing, params, num,
				min_level, max_level, arg, unknown);
		if (irq_was_disabled && !irqs_disabled())
			pr_warn("%s: option '%s' enabled irq's!\n",
				doing, param);

		switch (ret) {
		case -ENOENT:
			pr_err("%s: Unknown parameter `%s'\n", doing, param);
			return ERR_PTR(ret);
		case -ENOSPC:
			pr_err("%s: `%s' too large for parameter `%s'\n",
			       doing, val ?: "", param);
			return ERR_PTR(ret);
		case 0:
			break;
		default:
			pr_err("%s: `%s' invalid for parameter `%s'\n",
			       doing, val ?: "", param);
			return ERR_PTR(ret);
		}
	}

	/* All parsed OK. */
	return NULL;
}

/* Lazy bastard, eh? */
#define STANDARD_PARAM_DEF(name, type, format, strtolfn)      		\
	int param_set_##name(const char *val, const struct kernel_param *kp) \
	{								\
		return strtolfn(val, 0, (type *)kp->arg);		\
	}								\
	int param_get_##name(char *buffer, const struct kernel_param *kp) \
	{								\
		return scnprintf(buffer, PAGE_SIZE, format,		\
				*((type *)kp->arg));			\
	}								\
	const struct kernel_param_ops param_ops_##name = {			\
		.set = param_set_##name,				\
		.get = param_get_##name,				\
	};								\
	EXPORT_SYMBOL(param_set_##name);				\
	EXPORT_SYMBOL(param_get_##name);				\
	EXPORT_SYMBOL(param_ops_##name)


STANDARD_PARAM_DEF(byte, unsigned char, "%hhu", kstrtou8);
STANDARD_PARAM_DEF(short, short, "%hi", kstrtos16);
STANDARD_PARAM_DEF(ushort, unsigned short, "%hu", kstrtou16);
STANDARD_PARAM_DEF(int, int, "%i", kstrtoint);
STANDARD_PARAM_DEF(uint, unsigned int, "%u", kstrtouint);
STANDARD_PARAM_DEF(long, long, "%li", kstrtol);
STANDARD_PARAM_DEF(ulong, unsigned long, "%lu", kstrtoul);
STANDARD_PARAM_DEF(ullong, unsigned long long, "%llu", kstrtoull);

int param_set_charp(const char *val, const struct kernel_param *kp)
{
	if (strlen(val) > 1024) {
		pr_err("%s: string parameter too long\n", kp->name);
		return -ENOSPC;
	}

	maybe_kfree_parameter(*(char **)kp->arg);

	/* This is a hack.  We can't kmalloc in early boot, and we
	 * don't need to; this mangled commandline is preserved. */
	if (slab_is_available()) {
		*(char **)kp->arg = kmalloc_parameter(strlen(val)+1);
		if (!*(char **)kp->arg)
			return -ENOMEM;
		strcpy(*(char **)kp->arg, val);
	} else
		*(const char **)kp->arg = val;

	return 0;
}
EXPORT_SYMBOL(param_set_charp);

int param_get_charp(char *buffer, const struct kernel_param *kp)
{
	return scnprintf(buffer, PAGE_SIZE, "%s", *((char **)kp->arg));
}
EXPORT_SYMBOL(param_get_charp);

static void param_free_charp(void *arg)
{
	maybe_kfree_parameter(*((char **)arg));
}

const struct kernel_param_ops param_ops_charp = {
	.set = param_set_charp,
	.get = param_get_charp,
	.free = param_free_charp,
};
EXPORT_SYMBOL(param_ops_charp);

/* Actually could be a bool or an int, for historical reasons. */
int param_set_bool(const char *val, const struct kernel_param *kp)
{
	/* No equals means "set"... */
	if (!val) val = "1";

	/* One of =[yYnN01] */
	return strtobool(val, kp->arg);
}
EXPORT_SYMBOL(param_set_bool);

int param_get_bool(char *buffer, const struct kernel_param *kp)
{
	/* Y and N chosen as being relatively non-coder friendly */
	return sprintf(buffer, "%c", *(bool *)kp->arg ? 'Y' : 'N');
}
EXPORT_SYMBOL(param_get_bool);

const struct kernel_param_ops param_ops_bool = {
	.flags = KERNEL_PARAM_OPS_FL_NOARG,
	.set = param_set_bool,
	.get = param_get_bool,
};
EXPORT_SYMBOL(param_ops_bool);

int param_set_bool_enable_only(const char *val, const struct kernel_param *kp)
{
	int err = 0;
	bool new_value;
	bool orig_value = *(bool *)kp->arg;
	struct kernel_param dummy_kp = *kp;

	dummy_kp.arg = &new_value;

	err = param_set_bool(val, &dummy_kp);
	if (err)
		return err;

	/* Don't let them unset it once it's set! */
	if (!new_value && orig_value)
		return -EROFS;

	if (new_value)
		err = param_set_bool(val, kp);

	return err;
}
EXPORT_SYMBOL_GPL(param_set_bool_enable_only);

const struct kernel_param_ops param_ops_bool_enable_only = {
	.flags = KERNEL_PARAM_OPS_FL_NOARG,
	.set = param_set_bool_enable_only,
	.get = param_get_bool,
};
EXPORT_SYMBOL_GPL(param_ops_bool_enable_only);

/* This one must be bool. */
int param_set_invbool(const char *val, const struct kernel_param *kp)
{
	int ret;
	bool boolval;
	struct kernel_param dummy;

	dummy.arg = &boolval;
	ret = param_set_bool(val, &dummy);
	if (ret == 0)
		*(bool *)kp->arg = !boolval;
	return ret;
}
EXPORT_SYMBOL(param_set_invbool);

int param_get_invbool(char *buffer, const struct kernel_param *kp)
{
	return sprintf(buffer, "%c", (*(bool *)kp->arg) ? 'N' : 'Y');
}
EXPORT_SYMBOL(param_get_invbool);

const struct kernel_param_ops param_ops_invbool = {
	.set = param_set_invbool,
	.get = param_get_invbool,
};
EXPORT_SYMBOL(param_ops_invbool);

int param_set_bint(const char *val, const struct kernel_param *kp)
{
	/* Match bool exactly, by re-using it. */
	struct kernel_param boolkp = *kp;
	bool v;
	int ret;

	boolkp.arg = &v;

	ret = param_set_bool(val, &boolkp);
	if (ret == 0)
		*(int *)kp->arg = v;
	return ret;
}
EXPORT_SYMBOL(param_set_bint);

const struct kernel_param_ops param_ops_bint = {
	.flags = KERNEL_PARAM_OPS_FL_NOARG,
	.set = param_set_bint,
	.get = param_get_int,
};
EXPORT_SYMBOL(param_ops_bint);

/* We break the rule and mangle the string. */
static int param_array(struct module *mod,
		       const char *name,
		       const char *val,
		       unsigned int min, unsigned int max,
		       void *elem, int elemsize,
		       int (*set)(const char *, const struct kernel_param *kp),
		       s16 level,
		       unsigned int *num)
{
	int ret;
	struct kernel_param kp;
	char save;

	/* Get the name right for errors. */
	kp.name = name;
	kp.arg = elem;
	kp.level = level;

	*num = 0;
	/* We expect a comma-separated list of values. */
	do {
		int len;

		if (*num == max) {
			pr_err("%s: can only take %i arguments\n", name, max);
			return -EINVAL;
		}
		len = strcspn(val, ",");

		/* nul-terminate and parse */
		save = val[len];
		((char *)val)[len] = '\0';
		check_kparam_locked(mod);
		ret = set(val, &kp);

		if (ret != 0)
			return ret;
		kp.arg += elemsize;
		val += len+1;
		(*num)++;
	} while (save == ',');

	if (*num < min) {
		pr_err("%s: needs at least %i arguments\n", name, min);
		return -EINVAL;
	}
	return 0;
}

static int param_array_set(const char *val, const struct kernel_param *kp)
{
	const struct kparam_array *arr = kp->arr;
	unsigned int temp_num;

	return param_array(kp->mod, kp->name, val, 1, arr->max, arr->elem,
			   arr->elemsize, arr->ops->set, kp->level,
			   arr->num ?: &temp_num);
}

static int param_array_get(char *buffer, const struct kernel_param *kp)
{
	int i, off, ret;
	const struct kparam_array *arr = kp->arr;
	struct kernel_param p = *kp;

	for (i = off = 0; i < (arr->num ? *arr->num : arr->max); i++) {
		if (i)
			buffer[off++] = ',';
		p.arg = arr->elem + arr->elemsize * i;
		check_kparam_locked(p.mod);
		ret = arr->ops->get(buffer + off, &p);
		if (ret < 0)
			return ret;
		off += ret;
	}
	buffer[off] = '\0';
	return off;
}

static void param_array_free(void *arg)
{
	unsigned int i;
	const struct kparam_array *arr = arg;

	if (arr->ops->free)
		for (i = 0; i < (arr->num ? *arr->num : arr->max); i++)
			arr->ops->free(arr->elem + arr->elemsize * i);
}

const struct kernel_param_ops param_array_ops = {
	.set = param_array_set,
	.get = param_array_get,
	.free = param_array_free,
};
EXPORT_SYMBOL(param_array_ops);

int param_set_copystring(const char *val, const struct kernel_param *kp)
{
	const struct kparam_string *kps = kp->str;

	if (strlen(val)+1 > kps->maxlen) {
		pr_err("%s: string doesn't fit in %u chars.\n",
		       kp->name, kps->maxlen-1);
		return -ENOSPC;
	}
	strcpy(kps->string, val);
	return 0;
}
EXPORT_SYMBOL(param_set_copystring);

int param_get_string(char *buffer, const struct kernel_param *kp)
{
	const struct kparam_string *kps = kp->str;
	return strlcpy(buffer, kps->string, kps->maxlen);
}
EXPORT_SYMBOL(param_get_string);

const struct kernel_param_ops param_ops_string = {
	.set = param_set_copystring,
	.get = param_get_string,
};
EXPORT_SYMBOL(param_ops_string);

/* sysfs output in /sys/modules/XYZ/parameters/ */
#define to_module_attr(n) container_of(n, struct module_attribute, attr)
#define to_module_kobject(n) container_of(n, struct module_kobject, kobj)

struct param_attribute
{
	struct module_attribute mattr;
	const struct kernel_param *param;
};

struct module_param_attrs
{
	unsigned int num;
	struct attribute_group grp;
	struct param_attribute attrs[0];
};

#ifdef CONFIG_SYSFS
#define to_param_attr(n) container_of(n, struct param_attribute, mattr)

static ssize_t param_attr_show(struct module_attribute *mattr,
			       struct module_kobject *mk, char *buf)
{
	int count;
	struct param_attribute *attribute = to_param_attr(mattr);

	if (!attribute->param->ops->get)
		return -EPERM;

	kernel_param_lock(mk->mod);
	count = attribute->param->ops->get(buf, attribute->param);
	kernel_param_unlock(mk->mod);
	if (count > 0) {
		strcat(buf, "\n");
		++count;
	}
	return count;
}

/* sysfs always hands a nul-terminated string in buf.  We rely on that. */
static ssize_t param_attr_store(struct module_attribute *mattr,
				struct module_kobject *mk,
				const char *buf, size_t len)
{
 	int err;
	struct param_attribute *attribute = to_param_attr(mattr);

	if (!attribute->param->ops->set)
		return -EPERM;

	kernel_param_lock(mk->mod);
	param_check_unsafe(attribute->param);
	err = attribute->param->ops->set(buf, attribute->param);
	kernel_param_unlock(mk->mod);
	if (!err)
		return len;
	return err;
}
#endif

#ifdef CONFIG_MODULES
#define __modinit
#else
#define __modinit __init
#endif

#ifdef CONFIG_SYSFS
void kernel_param_lock(struct module *mod)
{
	mutex_lock(KPARAM_MUTEX(mod));
}

void kernel_param_unlock(struct module *mod)
{
	mutex_unlock(KPARAM_MUTEX(mod));
}

EXPORT_SYMBOL(kernel_param_lock);
EXPORT_SYMBOL(kernel_param_unlock);

/*
 * add_sysfs_param - add a parameter to sysfs
 * @mk: struct module_kobject
 * @kparam: the actual parameter definition to add to sysfs
 * @name: name of parameter
 *
 * Create a kobject if for a (per-module) parameter if mp NULL, and
 * create file in sysfs.  Returns an error on out of memory.  Always cleans up
 * if there's an error.
 */
static __modinit int add_sysfs_param(struct module_kobject *mk,
				     const struct kernel_param *kp,
				     const char *name)
{
	struct module_param_attrs *new_mp;
	struct attribute **new_attrs;
	unsigned int i;

	/* We don't bother calling this with invisible parameters. */
	BUG_ON(!kp->perm);

	if (!mk->mp) {
		/* First allocation. */
		mk->mp = kzalloc(sizeof(*mk->mp), GFP_KERNEL);
		if (!mk->mp)
			return -ENOMEM;
		mk->mp->grp.name = "parameters";
		/* NULL-terminated attribute array. */
		mk->mp->grp.attrs = kzalloc(sizeof(mk->mp->grp.attrs[0]),
					    GFP_KERNEL);
		/* Caller will cleanup via free_module_param_attrs */
		if (!mk->mp->grp.attrs)
			return -ENOMEM;
	}

	/* Enlarge allocations. */
	new_mp = krealloc(mk->mp,
			  sizeof(*mk->mp) +
			  sizeof(mk->mp->attrs[0]) * (mk->mp->num + 1),
			  GFP_KERNEL);
	if (!new_mp)
		return -ENOMEM;
	mk->mp = new_mp;

	/* Extra pointer for NULL terminator */
	new_attrs = krealloc(mk->mp->grp.attrs,
			     sizeof(mk->mp->grp.attrs[0]) * (mk->mp->num + 2),
			     GFP_KERNEL);
	if (!new_attrs)
		return -ENOMEM;
	mk->mp->grp.attrs = new_attrs;

	/* Tack new one on the end. */
	memset(&mk->mp->attrs[mk->mp->num], 0, sizeof(mk->mp->attrs[0]));
	sysfs_attr_init(&mk->mp->attrs[mk->mp->num].mattr.attr);
	mk->mp->attrs[mk->mp->num].param = kp;
	mk->mp->attrs[mk->mp->num].mattr.show = param_attr_show;
	/* Do not allow runtime DAC changes to make param writable. */
	if ((kp->perm & (S_IWUSR | S_IWGRP | S_IWOTH)) != 0)
		mk->mp->attrs[mk->mp->num].mattr.store = param_attr_store;
	else
		mk->mp->attrs[mk->mp->num].mattr.store = NULL;
	mk->mp->attrs[mk->mp->num].mattr.attr.name = (char *)name;
	mk->mp->attrs[mk->mp->num].mattr.attr.mode = kp->perm;
	mk->mp->num++;

	/* Fix up all the pointers, since krealloc can move us */
	for (i = 0; i < mk->mp->num; i++)
		mk->mp->grp.attrs[i] = &mk->mp->attrs[i].mattr.attr;
	mk->mp->grp.attrs[mk->mp->num] = NULL;
	return 0;
}

#ifdef CONFIG_MODULES
static void free_module_param_attrs(struct module_kobject *mk)
{
	if (mk->mp)
		kfree(mk->mp->grp.attrs);
	kfree(mk->mp);
	mk->mp = NULL;
}

/*
 * module_param_sysfs_setup - setup sysfs support for one module
 * @mod: module
 * @kparam: module parameters (array)
 * @num_params: number of module parameters
 *
 * Adds sysfs entries for module parameters under
 * /sys/module/[mod->name]/parameters/
 */
int module_param_sysfs_setup(struct module *mod,
			     const struct kernel_param *kparam,
			     unsigned int num_params)
{
	int i, err;
	bool params = false;

	for (i = 0; i < num_params; i++) {
		if (kparam[i].perm == 0)
			continue;
		err = add_sysfs_param(&mod->mkobj, &kparam[i], kparam[i].name);
		if (err) {
			free_module_param_attrs(&mod->mkobj);
			return err;
		}
		params = true;
	}

	if (!params)
		return 0;

	/* Create the param group. */
	err = sysfs_create_group(&mod->mkobj.kobj, &mod->mkobj.mp->grp);
	if (err)
		free_module_param_attrs(&mod->mkobj);
	return err;
}

/*
 * module_param_sysfs_remove - remove sysfs support for one module
 * @mod: module
 *
 * Remove sysfs entries for module parameters and the corresponding
 * kobject.
 */
void module_param_sysfs_remove(struct module *mod)
{
	if (mod->mkobj.mp) {
		sysfs_remove_group(&mod->mkobj.kobj, &mod->mkobj.mp->grp);
		/* We are positive that no one is using any param
		 * attrs at this point.  Deallocate immediately. */
		free_module_param_attrs(&mod->mkobj);
	}
}
#endif

void destroy_params(const struct kernel_param *params, unsigned num)
{
	unsigned int i;

	for (i = 0; i < num; i++)
		if (params[i].ops->free)
			params[i].ops->free(params[i].arg);
}

static struct module_kobject * __init locate_module_kobject(const char *name)
{
	struct module_kobject *mk;
	struct kobject *kobj;
	int err;

	kobj = kset_find_obj(module_kset, name);
	if (kobj) {
		mk = to_module_kobject(kobj);
	} else {
		mk = kzalloc(sizeof(struct module_kobject), GFP_KERNEL);
		BUG_ON(!mk);

		mk->mod = THIS_MODULE;
		mk->kobj.kset = module_kset;
		err = kobject_init_and_add(&mk->kobj, &module_ktype, NULL,
					   "%s", name);
#ifdef CONFIG_MODULES
		if (!err)
			err = sysfs_create_file(&mk->kobj, &module_uevent.attr);
#endif
		if (err) {
			kobject_put(&mk->kobj);
			pr_crit("Adding module '%s' to sysfs failed (%d), the system may be unstable.\n",
				name, err);
			return NULL;
		}

		/* So that we hold reference in both cases. */
		kobject_get(&mk->kobj);
	}

	return mk;
}

static void __init kernel_add_sysfs_param(const char *name,
					  const struct kernel_param *kparam,
					  unsigned int name_skip)
{
	struct module_kobject *mk;
	int err;

	mk = locate_module_kobject(name);
	if (!mk)
		return;

	/* We need to remove old parameters before adding more. */
	if (mk->mp)
		sysfs_remove_group(&mk->kobj, &mk->mp->grp);

	/* These should not fail at boot. */
	err = add_sysfs_param(mk, kparam, kparam->name + name_skip);
	BUG_ON(err);
	err = sysfs_create_group(&mk->kobj, &mk->mp->grp);
	BUG_ON(err);
	kobject_uevent(&mk->kobj, KOBJ_ADD);
	kobject_put(&mk->kobj);
}

/*
 * param_sysfs_builtin - add sysfs parameters for built-in modules
 *
 * Add module_parameters to sysfs for "modules" built into the kernel.
 *
 * The "module" name (KBUILD_MODNAME) is stored before a dot, the
 * "parameter" name is stored behind a dot in kernel_param->name. So,
 * extract the "module" name for all built-in kernel_param-eters,
 * and for all who have the same, call kernel_add_sysfs_param.
 */
static void __init param_sysfs_builtin(void)
{
	const struct kernel_param *kp;
	unsigned int name_len;
	char modname[MODULE_NAME_LEN];

	for (kp = __start___param; kp < __stop___param; kp++) {
		char *dot;

		if (kp->perm == 0)
			continue;

		dot = strchr(kp->name, '.');
		if (!dot) {
			/* This happens for core_param() */
			strcpy(modname, "kernel");
			name_len = 0;
		} else {
			name_len = dot - kp->name + 1;
			strlcpy(modname, kp->name, name_len);
		}
		kernel_add_sysfs_param(modname, kp, name_len);
	}
}

ssize_t __modver_version_show(struct module_attribute *mattr,
			      struct module_kobject *mk, char *buf)
{
	struct module_version_attribute *vattr =
		container_of(mattr, struct module_version_attribute, mattr);

	return scnprintf(buf, PAGE_SIZE, "%s\n", vattr->version);
}

extern const struct module_version_attribute *__start___modver[];
extern const struct module_version_attribute *__stop___modver[];

static void __init version_sysfs_builtin(void)
{
	const struct module_version_attribute **p;
	struct module_kobject *mk;
	int err;

	for (p = __start___modver; p < __stop___modver; p++) {
		const struct module_version_attribute *vattr = *p;

		mk = locate_module_kobject(vattr->module_name);
		if (mk) {
			err = sysfs_create_file(&mk->kobj, &vattr->mattr.attr);
			WARN_ON_ONCE(err);
			kobject_uevent(&mk->kobj, KOBJ_ADD);
			kobject_put(&mk->kobj);
		}
	}
}

/* module-related sysfs stuff */

static ssize_t module_attr_show(struct kobject *kobj,
				struct attribute *attr,
				char *buf)
{
	struct module_attribute *attribute;
	struct module_kobject *mk;
	int ret;

	attribute = to_module_attr(attr);
	mk = to_module_kobject(kobj);

	if (!attribute->show)
		return -EIO;

	ret = attribute->show(attribute, mk, buf);

	return ret;
}

static ssize_t module_attr_store(struct kobject *kobj,
				struct attribute *attr,
				const char *buf, size_t len)
{
	struct module_attribute *attribute;
	struct module_kobject *mk;
	int ret;

	attribute = to_module_attr(attr);
	mk = to_module_kobject(kobj);

	if (!attribute->store)
		return -EIO;

	ret = attribute->store(attribute, mk, buf, len);

	return ret;
}

static const struct sysfs_ops module_sysfs_ops = {
	.show = module_attr_show,
	.store = module_attr_store,
};

static int uevent_filter(struct kset *kset, struct kobject *kobj)
{
	struct kobj_type *ktype = get_ktype(kobj);

	if (ktype == &module_ktype)
		return 1;
	return 0;
}

static const struct kset_uevent_ops module_uevent_ops = {
	.filter = uevent_filter,
};

struct kset *module_kset;
int module_sysfs_initialized;

static void module_kobj_release(struct kobject *kobj)
{
	struct module_kobject *mk = to_module_kobject(kobj);
	complete(mk->kobj_completion);
}

struct kobj_type module_ktype = {
	.release   =	module_kobj_release,
	.sysfs_ops =	&module_sysfs_ops,
};

/*
 * param_sysfs_init - wrapper for built-in params support
 */
static int __init param_sysfs_init(void)
{
	module_kset = kset_create_and_add("module", &module_uevent_ops, NULL);
	if (!module_kset) {
		printk(KERN_WARNING "%s (%d): error creating kset\n",
			__FILE__, __LINE__);
		return -ENOMEM;
	}
	module_sysfs_initialized = 1;

	version_sysfs_builtin();
	param_sysfs_builtin();

	return 0;
}
subsys_initcall(param_sysfs_init);

#endif /* CONFIG_SYSFS */