xref: /linux/kernel/params.c (revision f2ee442115c9b6219083c019939a9cc0c9abb2f8)
1 /* Helpers for initial module or kernel cmdline parsing
2    Copyright (C) 2001 Rusty Russell.
3 
4     This program is free software; you can redistribute it and/or modify
5     it under the terms of the GNU General Public License as published by
6     the Free Software Foundation; either version 2 of the License, or
7     (at your option) any later version.
8 
9     This program is distributed in the hope that it will be useful,
10     but WITHOUT ANY WARRANTY; without even the implied warranty of
11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12     GNU General Public License for more details.
13 
14     You should have received a copy of the GNU General Public License
15     along with this program; if not, write to the Free Software
16     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
17 */
18 #include <linux/module.h>
19 #include <linux/kernel.h>
20 #include <linux/string.h>
21 #include <linux/errno.h>
22 #include <linux/module.h>
23 #include <linux/device.h>
24 #include <linux/err.h>
25 #include <linux/slab.h>
26 #include <linux/ctype.h>
27 
28 #if 0
29 #define DEBUGP printk
30 #else
31 #define DEBUGP(fmt, a...)
32 #endif
33 
34 /* Protects all parameters, and incidentally kmalloced_param list. */
35 static DEFINE_MUTEX(param_lock);
36 
37 /* This just allows us to keep track of which parameters are kmalloced. */
38 struct kmalloced_param {
39 	struct list_head list;
40 	char val[];
41 };
42 static LIST_HEAD(kmalloced_params);
43 
44 static void *kmalloc_parameter(unsigned int size)
45 {
46 	struct kmalloced_param *p;
47 
48 	p = kmalloc(sizeof(*p) + size, GFP_KERNEL);
49 	if (!p)
50 		return NULL;
51 
52 	list_add(&p->list, &kmalloced_params);
53 	return p->val;
54 }
55 
56 /* Does nothing if parameter wasn't kmalloced above. */
57 static void maybe_kfree_parameter(void *param)
58 {
59 	struct kmalloced_param *p;
60 
61 	list_for_each_entry(p, &kmalloced_params, list) {
62 		if (p->val == param) {
63 			list_del(&p->list);
64 			kfree(p);
65 			break;
66 		}
67 	}
68 }
69 
70 static char dash2underscore(char c)
71 {
72 	if (c == '-')
73 		return '_';
74 	return c;
75 }
76 
77 bool parameqn(const char *a, const char *b, size_t n)
78 {
79 	size_t i;
80 
81 	for (i = 0; i < n; i++) {
82 		if (dash2underscore(a[i]) != dash2underscore(b[i]))
83 			return false;
84 	}
85 	return true;
86 }
87 
88 bool parameq(const char *a, const char *b)
89 {
90 	return parameqn(a, b, strlen(a)+1);
91 }
92 
93 static int parse_one(char *param,
94 		     char *val,
95 		     const struct kernel_param *params,
96 		     unsigned num_params,
97 		     int (*handle_unknown)(char *param, char *val))
98 {
99 	unsigned int i;
100 	int err;
101 
102 	/* Find parameter */
103 	for (i = 0; i < num_params; i++) {
104 		if (parameq(param, params[i].name)) {
105 			/* No one handled NULL, so do it here. */
106 			if (!val && params[i].ops->set != param_set_bool)
107 				return -EINVAL;
108 			DEBUGP("They are equal!  Calling %p\n",
109 			       params[i].ops->set);
110 			mutex_lock(&param_lock);
111 			err = params[i].ops->set(val, &params[i]);
112 			mutex_unlock(&param_lock);
113 			return err;
114 		}
115 	}
116 
117 	if (handle_unknown) {
118 		DEBUGP("Unknown argument: calling %p\n", handle_unknown);
119 		return handle_unknown(param, val);
120 	}
121 
122 	DEBUGP("Unknown argument `%s'\n", param);
123 	return -ENOENT;
124 }
125 
126 /* You can use " around spaces, but can't escape ". */
127 /* Hyphens and underscores equivalent in parameter names. */
128 static char *next_arg(char *args, char **param, char **val)
129 {
130 	unsigned int i, equals = 0;
131 	int in_quote = 0, quoted = 0;
132 	char *next;
133 
134 	if (*args == '"') {
135 		args++;
136 		in_quote = 1;
137 		quoted = 1;
138 	}
139 
140 	for (i = 0; args[i]; i++) {
141 		if (isspace(args[i]) && !in_quote)
142 			break;
143 		if (equals == 0) {
144 			if (args[i] == '=')
145 				equals = i;
146 		}
147 		if (args[i] == '"')
148 			in_quote = !in_quote;
149 	}
150 
151 	*param = args;
152 	if (!equals)
153 		*val = NULL;
154 	else {
155 		args[equals] = '\0';
156 		*val = args + equals + 1;
157 
158 		/* Don't include quotes in value. */
159 		if (**val == '"') {
160 			(*val)++;
161 			if (args[i-1] == '"')
162 				args[i-1] = '\0';
163 		}
164 		if (quoted && args[i-1] == '"')
165 			args[i-1] = '\0';
166 	}
167 
168 	if (args[i]) {
169 		args[i] = '\0';
170 		next = args + i + 1;
171 	} else
172 		next = args + i;
173 
174 	/* Chew up trailing spaces. */
175 	return skip_spaces(next);
176 }
177 
178 /* Args looks like "foo=bar,bar2 baz=fuz wiz". */
179 int parse_args(const char *name,
180 	       char *args,
181 	       const struct kernel_param *params,
182 	       unsigned num,
183 	       int (*unknown)(char *param, char *val))
184 {
185 	char *param, *val;
186 
187 	DEBUGP("Parsing ARGS: %s\n", args);
188 
189 	/* Chew leading spaces */
190 	args = skip_spaces(args);
191 
192 	while (*args) {
193 		int ret;
194 		int irq_was_disabled;
195 
196 		args = next_arg(args, &param, &val);
197 		irq_was_disabled = irqs_disabled();
198 		ret = parse_one(param, val, params, num, unknown);
199 		if (irq_was_disabled && !irqs_disabled()) {
200 			printk(KERN_WARNING "parse_args(): option '%s' enabled "
201 					"irq's!\n", param);
202 		}
203 		switch (ret) {
204 		case -ENOENT:
205 			printk(KERN_ERR "%s: Unknown parameter `%s'\n",
206 			       name, param);
207 			return ret;
208 		case -ENOSPC:
209 			printk(KERN_ERR
210 			       "%s: `%s' too large for parameter `%s'\n",
211 			       name, val ?: "", param);
212 			return ret;
213 		case 0:
214 			break;
215 		default:
216 			printk(KERN_ERR
217 			       "%s: `%s' invalid for parameter `%s'\n",
218 			       name, val ?: "", param);
219 			return ret;
220 		}
221 	}
222 
223 	/* All parsed OK. */
224 	return 0;
225 }
226 
227 /* Lazy bastard, eh? */
228 #define STANDARD_PARAM_DEF(name, type, format, tmptype, strtolfn)      	\
229 	int param_set_##name(const char *val, const struct kernel_param *kp) \
230 	{								\
231 		tmptype l;						\
232 		int ret;						\
233 									\
234 		ret = strtolfn(val, 0, &l);				\
235 		if (ret < 0 || ((type)l != l))				\
236 			return ret < 0 ? ret : -EINVAL;			\
237 		*((type *)kp->arg) = l;					\
238 		return 0;						\
239 	}								\
240 	int param_get_##name(char *buffer, const struct kernel_param *kp) \
241 	{								\
242 		return sprintf(buffer, format, *((type *)kp->arg));	\
243 	}								\
244 	struct kernel_param_ops param_ops_##name = {			\
245 		.set = param_set_##name,				\
246 		.get = param_get_##name,				\
247 	};								\
248 	EXPORT_SYMBOL(param_set_##name);				\
249 	EXPORT_SYMBOL(param_get_##name);				\
250 	EXPORT_SYMBOL(param_ops_##name)
251 
252 
253 STANDARD_PARAM_DEF(byte, unsigned char, "%c", unsigned long, strict_strtoul);
254 STANDARD_PARAM_DEF(short, short, "%hi", long, strict_strtol);
255 STANDARD_PARAM_DEF(ushort, unsigned short, "%hu", unsigned long, strict_strtoul);
256 STANDARD_PARAM_DEF(int, int, "%i", long, strict_strtol);
257 STANDARD_PARAM_DEF(uint, unsigned int, "%u", unsigned long, strict_strtoul);
258 STANDARD_PARAM_DEF(long, long, "%li", long, strict_strtol);
259 STANDARD_PARAM_DEF(ulong, unsigned long, "%lu", unsigned long, strict_strtoul);
260 
261 int param_set_charp(const char *val, const struct kernel_param *kp)
262 {
263 	if (strlen(val) > 1024) {
264 		printk(KERN_ERR "%s: string parameter too long\n",
265 		       kp->name);
266 		return -ENOSPC;
267 	}
268 
269 	maybe_kfree_parameter(*(char **)kp->arg);
270 
271 	/* This is a hack.  We can't kmalloc in early boot, and we
272 	 * don't need to; this mangled commandline is preserved. */
273 	if (slab_is_available()) {
274 		*(char **)kp->arg = kmalloc_parameter(strlen(val)+1);
275 		if (!*(char **)kp->arg)
276 			return -ENOMEM;
277 		strcpy(*(char **)kp->arg, val);
278 	} else
279 		*(const char **)kp->arg = val;
280 
281 	return 0;
282 }
283 EXPORT_SYMBOL(param_set_charp);
284 
285 int param_get_charp(char *buffer, const struct kernel_param *kp)
286 {
287 	return sprintf(buffer, "%s", *((char **)kp->arg));
288 }
289 EXPORT_SYMBOL(param_get_charp);
290 
291 static void param_free_charp(void *arg)
292 {
293 	maybe_kfree_parameter(*((char **)arg));
294 }
295 
296 struct kernel_param_ops param_ops_charp = {
297 	.set = param_set_charp,
298 	.get = param_get_charp,
299 	.free = param_free_charp,
300 };
301 EXPORT_SYMBOL(param_ops_charp);
302 
303 /* Actually could be a bool or an int, for historical reasons. */
304 int param_set_bool(const char *val, const struct kernel_param *kp)
305 {
306 	bool v;
307 	int ret;
308 
309 	/* No equals means "set"... */
310 	if (!val) val = "1";
311 
312 	/* One of =[yYnN01] */
313 	ret = strtobool(val, &v);
314 	if (ret)
315 		return ret;
316 
317 	if (kp->flags & KPARAM_ISBOOL)
318 		*(bool *)kp->arg = v;
319 	else
320 		*(int *)kp->arg = v;
321 	return 0;
322 }
323 EXPORT_SYMBOL(param_set_bool);
324 
325 int param_get_bool(char *buffer, const struct kernel_param *kp)
326 {
327 	bool val;
328 	if (kp->flags & KPARAM_ISBOOL)
329 		val = *(bool *)kp->arg;
330 	else
331 		val = *(int *)kp->arg;
332 
333 	/* Y and N chosen as being relatively non-coder friendly */
334 	return sprintf(buffer, "%c", val ? 'Y' : 'N');
335 }
336 EXPORT_SYMBOL(param_get_bool);
337 
338 struct kernel_param_ops param_ops_bool = {
339 	.set = param_set_bool,
340 	.get = param_get_bool,
341 };
342 EXPORT_SYMBOL(param_ops_bool);
343 
344 /* This one must be bool. */
345 int param_set_invbool(const char *val, const struct kernel_param *kp)
346 {
347 	int ret;
348 	bool boolval;
349 	struct kernel_param dummy;
350 
351 	dummy.arg = &boolval;
352 	dummy.flags = KPARAM_ISBOOL;
353 	ret = param_set_bool(val, &dummy);
354 	if (ret == 0)
355 		*(bool *)kp->arg = !boolval;
356 	return ret;
357 }
358 EXPORT_SYMBOL(param_set_invbool);
359 
360 int param_get_invbool(char *buffer, const struct kernel_param *kp)
361 {
362 	return sprintf(buffer, "%c", (*(bool *)kp->arg) ? 'N' : 'Y');
363 }
364 EXPORT_SYMBOL(param_get_invbool);
365 
366 struct kernel_param_ops param_ops_invbool = {
367 	.set = param_set_invbool,
368 	.get = param_get_invbool,
369 };
370 EXPORT_SYMBOL(param_ops_invbool);
371 
372 /* We break the rule and mangle the string. */
373 static int param_array(const char *name,
374 		       const char *val,
375 		       unsigned int min, unsigned int max,
376 		       void *elem, int elemsize,
377 		       int (*set)(const char *, const struct kernel_param *kp),
378 		       u16 flags,
379 		       unsigned int *num)
380 {
381 	int ret;
382 	struct kernel_param kp;
383 	char save;
384 
385 	/* Get the name right for errors. */
386 	kp.name = name;
387 	kp.arg = elem;
388 	kp.flags = flags;
389 
390 	*num = 0;
391 	/* We expect a comma-separated list of values. */
392 	do {
393 		int len;
394 
395 		if (*num == max) {
396 			printk(KERN_ERR "%s: can only take %i arguments\n",
397 			       name, max);
398 			return -EINVAL;
399 		}
400 		len = strcspn(val, ",");
401 
402 		/* nul-terminate and parse */
403 		save = val[len];
404 		((char *)val)[len] = '\0';
405 		BUG_ON(!mutex_is_locked(&param_lock));
406 		ret = set(val, &kp);
407 
408 		if (ret != 0)
409 			return ret;
410 		kp.arg += elemsize;
411 		val += len+1;
412 		(*num)++;
413 	} while (save == ',');
414 
415 	if (*num < min) {
416 		printk(KERN_ERR "%s: needs at least %i arguments\n",
417 		       name, min);
418 		return -EINVAL;
419 	}
420 	return 0;
421 }
422 
423 static int param_array_set(const char *val, const struct kernel_param *kp)
424 {
425 	const struct kparam_array *arr = kp->arr;
426 	unsigned int temp_num;
427 
428 	return param_array(kp->name, val, 1, arr->max, arr->elem,
429 			   arr->elemsize, arr->ops->set, kp->flags,
430 			   arr->num ?: &temp_num);
431 }
432 
433 static int param_array_get(char *buffer, const struct kernel_param *kp)
434 {
435 	int i, off, ret;
436 	const struct kparam_array *arr = kp->arr;
437 	struct kernel_param p;
438 
439 	p = *kp;
440 	for (i = off = 0; i < (arr->num ? *arr->num : arr->max); i++) {
441 		if (i)
442 			buffer[off++] = ',';
443 		p.arg = arr->elem + arr->elemsize * i;
444 		BUG_ON(!mutex_is_locked(&param_lock));
445 		ret = arr->ops->get(buffer + off, &p);
446 		if (ret < 0)
447 			return ret;
448 		off += ret;
449 	}
450 	buffer[off] = '\0';
451 	return off;
452 }
453 
454 static void param_array_free(void *arg)
455 {
456 	unsigned int i;
457 	const struct kparam_array *arr = arg;
458 
459 	if (arr->ops->free)
460 		for (i = 0; i < (arr->num ? *arr->num : arr->max); i++)
461 			arr->ops->free(arr->elem + arr->elemsize * i);
462 }
463 
464 struct kernel_param_ops param_array_ops = {
465 	.set = param_array_set,
466 	.get = param_array_get,
467 	.free = param_array_free,
468 };
469 EXPORT_SYMBOL(param_array_ops);
470 
471 int param_set_copystring(const char *val, const struct kernel_param *kp)
472 {
473 	const struct kparam_string *kps = kp->str;
474 
475 	if (strlen(val)+1 > kps->maxlen) {
476 		printk(KERN_ERR "%s: string doesn't fit in %u chars.\n",
477 		       kp->name, kps->maxlen-1);
478 		return -ENOSPC;
479 	}
480 	strcpy(kps->string, val);
481 	return 0;
482 }
483 EXPORT_SYMBOL(param_set_copystring);
484 
485 int param_get_string(char *buffer, const struct kernel_param *kp)
486 {
487 	const struct kparam_string *kps = kp->str;
488 	return strlcpy(buffer, kps->string, kps->maxlen);
489 }
490 EXPORT_SYMBOL(param_get_string);
491 
492 struct kernel_param_ops param_ops_string = {
493 	.set = param_set_copystring,
494 	.get = param_get_string,
495 };
496 EXPORT_SYMBOL(param_ops_string);
497 
498 /* sysfs output in /sys/modules/XYZ/parameters/ */
499 #define to_module_attr(n) container_of(n, struct module_attribute, attr)
500 #define to_module_kobject(n) container_of(n, struct module_kobject, kobj)
501 
502 extern struct kernel_param __start___param[], __stop___param[];
503 
504 struct param_attribute
505 {
506 	struct module_attribute mattr;
507 	const struct kernel_param *param;
508 };
509 
510 struct module_param_attrs
511 {
512 	unsigned int num;
513 	struct attribute_group grp;
514 	struct param_attribute attrs[0];
515 };
516 
517 #ifdef CONFIG_SYSFS
518 #define to_param_attr(n) container_of(n, struct param_attribute, mattr)
519 
520 static ssize_t param_attr_show(struct module_attribute *mattr,
521 			       struct module_kobject *mk, char *buf)
522 {
523 	int count;
524 	struct param_attribute *attribute = to_param_attr(mattr);
525 
526 	if (!attribute->param->ops->get)
527 		return -EPERM;
528 
529 	mutex_lock(&param_lock);
530 	count = attribute->param->ops->get(buf, attribute->param);
531 	mutex_unlock(&param_lock);
532 	if (count > 0) {
533 		strcat(buf, "\n");
534 		++count;
535 	}
536 	return count;
537 }
538 
539 /* sysfs always hands a nul-terminated string in buf.  We rely on that. */
540 static ssize_t param_attr_store(struct module_attribute *mattr,
541 				struct module_kobject *km,
542 				const char *buf, size_t len)
543 {
544  	int err;
545 	struct param_attribute *attribute = to_param_attr(mattr);
546 
547 	if (!attribute->param->ops->set)
548 		return -EPERM;
549 
550 	mutex_lock(&param_lock);
551 	err = attribute->param->ops->set(buf, attribute->param);
552 	mutex_unlock(&param_lock);
553 	if (!err)
554 		return len;
555 	return err;
556 }
557 #endif
558 
559 #ifdef CONFIG_MODULES
560 #define __modinit
561 #else
562 #define __modinit __init
563 #endif
564 
565 #ifdef CONFIG_SYSFS
566 void __kernel_param_lock(void)
567 {
568 	mutex_lock(&param_lock);
569 }
570 EXPORT_SYMBOL(__kernel_param_lock);
571 
572 void __kernel_param_unlock(void)
573 {
574 	mutex_unlock(&param_lock);
575 }
576 EXPORT_SYMBOL(__kernel_param_unlock);
577 
578 /*
579  * add_sysfs_param - add a parameter to sysfs
580  * @mk: struct module_kobject
581  * @kparam: the actual parameter definition to add to sysfs
582  * @name: name of parameter
583  *
584  * Create a kobject if for a (per-module) parameter if mp NULL, and
585  * create file in sysfs.  Returns an error on out of memory.  Always cleans up
586  * if there's an error.
587  */
588 static __modinit int add_sysfs_param(struct module_kobject *mk,
589 				     const struct kernel_param *kp,
590 				     const char *name)
591 {
592 	struct module_param_attrs *new;
593 	struct attribute **attrs;
594 	int err, num;
595 
596 	/* We don't bother calling this with invisible parameters. */
597 	BUG_ON(!kp->perm);
598 
599 	if (!mk->mp) {
600 		num = 0;
601 		attrs = NULL;
602 	} else {
603 		num = mk->mp->num;
604 		attrs = mk->mp->grp.attrs;
605 	}
606 
607 	/* Enlarge. */
608 	new = krealloc(mk->mp,
609 		       sizeof(*mk->mp) + sizeof(mk->mp->attrs[0]) * (num+1),
610 		       GFP_KERNEL);
611 	if (!new) {
612 		kfree(mk->mp);
613 		err = -ENOMEM;
614 		goto fail;
615 	}
616 	attrs = krealloc(attrs, sizeof(new->grp.attrs[0])*(num+2), GFP_KERNEL);
617 	if (!attrs) {
618 		err = -ENOMEM;
619 		goto fail_free_new;
620 	}
621 
622 	/* Sysfs wants everything zeroed. */
623 	memset(new, 0, sizeof(*new));
624 	memset(&new->attrs[num], 0, sizeof(new->attrs[num]));
625 	memset(&attrs[num], 0, sizeof(attrs[num]));
626 	new->grp.name = "parameters";
627 	new->grp.attrs = attrs;
628 
629 	/* Tack new one on the end. */
630 	sysfs_attr_init(&new->attrs[num].mattr.attr);
631 	new->attrs[num].param = kp;
632 	new->attrs[num].mattr.show = param_attr_show;
633 	new->attrs[num].mattr.store = param_attr_store;
634 	new->attrs[num].mattr.attr.name = (char *)name;
635 	new->attrs[num].mattr.attr.mode = kp->perm;
636 	new->num = num+1;
637 
638 	/* Fix up all the pointers, since krealloc can move us */
639 	for (num = 0; num < new->num; num++)
640 		new->grp.attrs[num] = &new->attrs[num].mattr.attr;
641 	new->grp.attrs[num] = NULL;
642 
643 	mk->mp = new;
644 	return 0;
645 
646 fail_free_new:
647 	kfree(new);
648 fail:
649 	mk->mp = NULL;
650 	return err;
651 }
652 
653 #ifdef CONFIG_MODULES
654 static void free_module_param_attrs(struct module_kobject *mk)
655 {
656 	kfree(mk->mp->grp.attrs);
657 	kfree(mk->mp);
658 	mk->mp = NULL;
659 }
660 
661 /*
662  * module_param_sysfs_setup - setup sysfs support for one module
663  * @mod: module
664  * @kparam: module parameters (array)
665  * @num_params: number of module parameters
666  *
667  * Adds sysfs entries for module parameters under
668  * /sys/module/[mod->name]/parameters/
669  */
670 int module_param_sysfs_setup(struct module *mod,
671 			     const struct kernel_param *kparam,
672 			     unsigned int num_params)
673 {
674 	int i, err;
675 	bool params = false;
676 
677 	for (i = 0; i < num_params; i++) {
678 		if (kparam[i].perm == 0)
679 			continue;
680 		err = add_sysfs_param(&mod->mkobj, &kparam[i], kparam[i].name);
681 		if (err)
682 			return err;
683 		params = true;
684 	}
685 
686 	if (!params)
687 		return 0;
688 
689 	/* Create the param group. */
690 	err = sysfs_create_group(&mod->mkobj.kobj, &mod->mkobj.mp->grp);
691 	if (err)
692 		free_module_param_attrs(&mod->mkobj);
693 	return err;
694 }
695 
696 /*
697  * module_param_sysfs_remove - remove sysfs support for one module
698  * @mod: module
699  *
700  * Remove sysfs entries for module parameters and the corresponding
701  * kobject.
702  */
703 void module_param_sysfs_remove(struct module *mod)
704 {
705 	if (mod->mkobj.mp) {
706 		sysfs_remove_group(&mod->mkobj.kobj, &mod->mkobj.mp->grp);
707 		/* We are positive that no one is using any param
708 		 * attrs at this point.  Deallocate immediately. */
709 		free_module_param_attrs(&mod->mkobj);
710 	}
711 }
712 #endif
713 
714 void destroy_params(const struct kernel_param *params, unsigned num)
715 {
716 	unsigned int i;
717 
718 	for (i = 0; i < num; i++)
719 		if (params[i].ops->free)
720 			params[i].ops->free(params[i].arg);
721 }
722 
723 static struct module_kobject * __init locate_module_kobject(const char *name)
724 {
725 	struct module_kobject *mk;
726 	struct kobject *kobj;
727 	int err;
728 
729 	kobj = kset_find_obj(module_kset, name);
730 	if (kobj) {
731 		mk = to_module_kobject(kobj);
732 	} else {
733 		mk = kzalloc(sizeof(struct module_kobject), GFP_KERNEL);
734 		BUG_ON(!mk);
735 
736 		mk->mod = THIS_MODULE;
737 		mk->kobj.kset = module_kset;
738 		err = kobject_init_and_add(&mk->kobj, &module_ktype, NULL,
739 					   "%s", name);
740 #ifdef CONFIG_MODULES
741 		if (!err)
742 			err = sysfs_create_file(&mk->kobj, &module_uevent.attr);
743 #endif
744 		if (err) {
745 			kobject_put(&mk->kobj);
746 			printk(KERN_ERR
747 				"Module '%s' failed add to sysfs, error number %d\n",
748 				name, err);
749 			printk(KERN_ERR
750 				"The system will be unstable now.\n");
751 			return NULL;
752 		}
753 
754 		/* So that we hold reference in both cases. */
755 		kobject_get(&mk->kobj);
756 	}
757 
758 	return mk;
759 }
760 
761 static void __init kernel_add_sysfs_param(const char *name,
762 					  struct kernel_param *kparam,
763 					  unsigned int name_skip)
764 {
765 	struct module_kobject *mk;
766 	int err;
767 
768 	mk = locate_module_kobject(name);
769 	if (!mk)
770 		return;
771 
772 	/* We need to remove old parameters before adding more. */
773 	if (mk->mp)
774 		sysfs_remove_group(&mk->kobj, &mk->mp->grp);
775 
776 	/* These should not fail at boot. */
777 	err = add_sysfs_param(mk, kparam, kparam->name + name_skip);
778 	BUG_ON(err);
779 	err = sysfs_create_group(&mk->kobj, &mk->mp->grp);
780 	BUG_ON(err);
781 	kobject_uevent(&mk->kobj, KOBJ_ADD);
782 	kobject_put(&mk->kobj);
783 }
784 
785 /*
786  * param_sysfs_builtin - add contents in /sys/parameters for built-in modules
787  *
788  * Add module_parameters to sysfs for "modules" built into the kernel.
789  *
790  * The "module" name (KBUILD_MODNAME) is stored before a dot, the
791  * "parameter" name is stored behind a dot in kernel_param->name. So,
792  * extract the "module" name for all built-in kernel_param-eters,
793  * and for all who have the same, call kernel_add_sysfs_param.
794  */
795 static void __init param_sysfs_builtin(void)
796 {
797 	struct kernel_param *kp;
798 	unsigned int name_len;
799 	char modname[MODULE_NAME_LEN];
800 
801 	for (kp = __start___param; kp < __stop___param; kp++) {
802 		char *dot;
803 
804 		if (kp->perm == 0)
805 			continue;
806 
807 		dot = strchr(kp->name, '.');
808 		if (!dot) {
809 			/* This happens for core_param() */
810 			strcpy(modname, "kernel");
811 			name_len = 0;
812 		} else {
813 			name_len = dot - kp->name + 1;
814 			strlcpy(modname, kp->name, name_len);
815 		}
816 		kernel_add_sysfs_param(modname, kp, name_len);
817 	}
818 }
819 
820 ssize_t __modver_version_show(struct module_attribute *mattr,
821 			      struct module_kobject *mk, char *buf)
822 {
823 	struct module_version_attribute *vattr =
824 		container_of(mattr, struct module_version_attribute, mattr);
825 
826 	return sprintf(buf, "%s\n", vattr->version);
827 }
828 
829 extern const struct module_version_attribute *__start___modver[];
830 extern const struct module_version_attribute *__stop___modver[];
831 
832 static void __init version_sysfs_builtin(void)
833 {
834 	const struct module_version_attribute **p;
835 	struct module_kobject *mk;
836 	int err;
837 
838 	for (p = __start___modver; p < __stop___modver; p++) {
839 		const struct module_version_attribute *vattr = *p;
840 
841 		mk = locate_module_kobject(vattr->module_name);
842 		if (mk) {
843 			err = sysfs_create_file(&mk->kobj, &vattr->mattr.attr);
844 			kobject_uevent(&mk->kobj, KOBJ_ADD);
845 			kobject_put(&mk->kobj);
846 		}
847 	}
848 }
849 
850 /* module-related sysfs stuff */
851 
852 static ssize_t module_attr_show(struct kobject *kobj,
853 				struct attribute *attr,
854 				char *buf)
855 {
856 	struct module_attribute *attribute;
857 	struct module_kobject *mk;
858 	int ret;
859 
860 	attribute = to_module_attr(attr);
861 	mk = to_module_kobject(kobj);
862 
863 	if (!attribute->show)
864 		return -EIO;
865 
866 	ret = attribute->show(attribute, mk, buf);
867 
868 	return ret;
869 }
870 
871 static ssize_t module_attr_store(struct kobject *kobj,
872 				struct attribute *attr,
873 				const char *buf, size_t len)
874 {
875 	struct module_attribute *attribute;
876 	struct module_kobject *mk;
877 	int ret;
878 
879 	attribute = to_module_attr(attr);
880 	mk = to_module_kobject(kobj);
881 
882 	if (!attribute->store)
883 		return -EIO;
884 
885 	ret = attribute->store(attribute, mk, buf, len);
886 
887 	return ret;
888 }
889 
890 static const struct sysfs_ops module_sysfs_ops = {
891 	.show = module_attr_show,
892 	.store = module_attr_store,
893 };
894 
895 static int uevent_filter(struct kset *kset, struct kobject *kobj)
896 {
897 	struct kobj_type *ktype = get_ktype(kobj);
898 
899 	if (ktype == &module_ktype)
900 		return 1;
901 	return 0;
902 }
903 
904 static const struct kset_uevent_ops module_uevent_ops = {
905 	.filter = uevent_filter,
906 };
907 
908 struct kset *module_kset;
909 int module_sysfs_initialized;
910 
911 struct kobj_type module_ktype = {
912 	.sysfs_ops =	&module_sysfs_ops,
913 };
914 
915 /*
916  * param_sysfs_init - wrapper for built-in params support
917  */
918 static int __init param_sysfs_init(void)
919 {
920 	module_kset = kset_create_and_add("module", &module_uevent_ops, NULL);
921 	if (!module_kset) {
922 		printk(KERN_WARNING "%s (%d): error creating kset\n",
923 			__FILE__, __LINE__);
924 		return -ENOMEM;
925 	}
926 	module_sysfs_initialized = 1;
927 
928 	version_sysfs_builtin();
929 	param_sysfs_builtin();
930 
931 	return 0;
932 }
933 subsys_initcall(param_sysfs_init);
934 
935 #endif /* CONFIG_SYSFS */
936