/* 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
  ",
  			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
  ", 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'
  ", doing, param, val);

  		return handle_unknown(param, val, doing, arg);

  	}

  	pr_debug("Unknown argument '%s'
  ", param);

  	return -ENOENT;
  }

  /* 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, *err = NULL;

  	/* Chew leading spaces */

  	args = skip_spaces(args);

  	if (*args)

  		pr_debug("doing %s, parsing ARGS: '%s'
  ", doing, args);

  	while (*args) {
  		int ret;

  		int irq_was_disabled;

  
  		args = next_arg(args, &param, &val);

  		/* Stop at -- */
  		if (!val && strcmp(param, "--") == 0)

  			return err ?: 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!
  ",
  				doing, param);

  		switch (ret) {

  		case 0:
  			continue;

  		case -ENOENT:

  			pr_err("%s: Unknown parameter `%s'
  ", doing, param);

  			break;

  		case -ENOSPC:

  			pr_err("%s: `%s' too large for parameter `%s'
  ",

  			       doing, val ?: "", param);

  			break;
  		default:

  			pr_err("%s: `%s' invalid for parameter `%s'
  ",

  			       doing, val ?: "", param);

  			break;

  		}

  
  		err = ERR_PTR(ret);

  	}

  	return err;

  }
  
  /* 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
  ", 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);

  void param_free_charp(void *arg)

  {
  	maybe_kfree_parameter(*((char **)arg));
  }

  EXPORT_SYMBOL(param_free_charp);

  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
  ", 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
  ", 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++) {

  		/* Replace 
   with comma */

  		if (i)

  			buffer[off - 1] = ',';

  		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.
  ",

  		       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 scnprintf(buffer, PAGE_SIZE, "%s
  ", kps->string);

  }

  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);

  	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

   * @kp: 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.
  ",

  				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
  ", 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
  ",
  			__FILE__, __LINE__);
  		return -ENOMEM;

  	}

  	module_sysfs_initialized = 1;

  	version_sysfs_builtin();

  	param_sysfs_builtin();
  
  	return 0;
  }

  subsys_initcall(param_sysfs_init);

  #endif /* CONFIG_SYSFS */