/* 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/device.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/ctype.h>

/* Protects all parameters, and incidentally kmalloced_param list. */
static DEFINE_MUTEX(param_lock);

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

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

        list_add(&p->list, &kmalloced_params);
        return p->val;
}

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

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

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 int parse_one(char *param,
                     char *val,
                     const char *doing,
                     const struct kernel_param *params,
                     unsigned num_params,
                     s16 min_level,
                     s16 max_level,
                     int (*handle_unknown)(char *param, char *val,
                                     const char *doing))
{
        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_FL_NOARG))
                                return -EINVAL;
                        pr_debug("handling %s with %p\n", param,
                                params[i].ops->set);
                        mutex_lock(&param_lock);
                        err = params[i].ops->set(val, &params[i]);
                        mutex_unlock(&param_lock);
                        return err;
                }
        }

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

        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". */
int parse_args(const char *doing,
               char *args,
               const struct kernel_param *params,
               unsigned num,
               s16 min_level,
               s16 max_level,
               int (*unknown)(char *param, char *val, const char *doing))
{
        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);
                irq_was_disabled = irqs_disabled();
                ret = parse_one(param, val, doing, params, num,
                                min_level, max_level, 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 ret;
                case -ENOSPC:
                        pr_err("%s: `%s' too large for parameter `%s'\n",
                               doing, val ?: "", param);
                        return ret;
                case 0:
                        break;
                default:
                        pr_err("%s: `%s' invalid for parameter `%s'\n",
                               doing, val ?: "", param);
                        return ret;
                }
        }

        /* All parsed OK. */
        return 0;
}

/* Lazy bastard, eh? */
#define STANDARD_PARAM_DEF(name, type, format, tmptype, strtolfn)       \
        int param_set_##name(const char *val, const struct kernel_param *kp) \
        {                                                               \
                tmptype l;                                              \
                int ret;                                                \
                                                                        \
                ret = strtolfn(val, 0, &l);                             \
                if (ret < 0 || ((type)l != l))                          \
                        return ret < 0 ? ret : -EINVAL;                 \
                *((type *)kp->arg) = l;                                 \
                return 0;                                               \
        }                                                               \
        int param_get_##name(char *buffer, const struct kernel_param *kp) \
        {                                                               \
                return scnprintf(buffer, PAGE_SIZE, format,             \
                                *((type *)kp->arg));                    \
        }                                                               \
        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", unsigned long, kstrtoul);
STANDARD_PARAM_DEF(short, short, "%hi", long, kstrtol);
STANDARD_PARAM_DEF(ushort, unsigned short, "%hu", unsigned long, kstrtoul);
STANDARD_PARAM_DEF(int, int, "%i", long, kstrtol);
STANDARD_PARAM_DEF(uint, unsigned int, "%u", unsigned long, kstrtoul);
STANDARD_PARAM_DEF(long, long, "%li", long, kstrtol);
STANDARD_PARAM_DEF(ulong, unsigned long, "%lu", unsigned long, kstrtoul);

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));
}

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);

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

/* 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);

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)
{
        struct kernel_param boolkp;
        bool v;
        int ret;

        /* Match bool exactly, by re-using it. */
        boolkp = *kp;
        boolkp.arg = &v;

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

struct kernel_param_ops param_ops_bint = {
        .flags = KERNEL_PARAM_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(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';
                BUG_ON(!mutex_is_locked(&param_lock));
                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->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;

        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;
                BUG_ON(!mutex_is_locked(&param_lock));
                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);
}

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);

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)

extern struct kernel_param __start___param[], __stop___param[];

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;

        mutex_lock(&param_lock);
        count = attribute->param->ops->get(buf, attribute->param);
        mutex_unlock(&param_lock);
        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 *km,
                                const char *buf, size_t len)
{
        int err;
        struct param_attribute *attribute = to_param_attr(mattr);

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

        mutex_lock(&param_lock);
        err = attribute->param->ops->set(buf, attribute->param);
        mutex_unlock(&param_lock);
        if (!err)
                return len;
        return err;
}
#endif

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

#ifdef CONFIG_SYSFS
void __kernel_param_lock(void)
{
        mutex_lock(&param_lock);
}
EXPORT_SYMBOL(__kernel_param_lock);

void __kernel_param_unlock(void)
{
        mutex_unlock(&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;
        struct attribute **attrs;
        int err, num;

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

        if (!mk->mp) {
                num = 0;
                attrs = NULL;
        } else {
                num = mk->mp->num;
                attrs = mk->mp->grp.attrs;
        }

        /* Enlarge. */
        new = krealloc(mk->mp,
                       sizeof(*mk->mp) + sizeof(mk->mp->attrs[0]) * (num+1),
                       GFP_KERNEL);
        if (!new) {
                kfree(attrs);
                err = -ENOMEM;
                goto fail;
        }
        /* Despite looking like the typical realloc() bug, this is safe.
         * We *want* the old 'attrs' to be freed either way, and we'll store
         * the new one in the success case. */
        attrs = krealloc(attrs, sizeof(new->grp.attrs[0])*(num+2), GFP_KERNEL);
        if (!attrs) {
                err = -ENOMEM;
                goto fail_free_new;
        }

        /* Sysfs wants everything zeroed. */
        memset(new, 0, sizeof(*new));
        memset(&new->attrs[num], 0, sizeof(new->attrs[num]));
        memset(&attrs[num], 0, sizeof(attrs[num]));
        new->grp.name = "parameters";
        new->grp.attrs = attrs;

        /* Tack new one on the end. */
        sysfs_attr_init(&new->attrs[num].mattr.attr);
        new->attrs[num].param = kp;
        new->attrs[num].mattr.show = param_attr_show;
        new->attrs[num].mattr.store = param_attr_store;
        new->attrs[num].mattr.attr.name = (char *)name;
        new->attrs[num].mattr.attr.mode = kp->perm;
        new->num = num+1;

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

        mk->mp = new;
        return 0;

fail_free_new:
        kfree(new);
fail:
        mk->mp = NULL;
        return err;
}

#ifdef CONFIG_MODULES
static void free_module_param_attrs(struct module_kobject *mk)
{
        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)
                        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,
                                          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)
{
        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);
                        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 */