linux/drivers/usb/gadget/configfs.c
Andrzej Pietrasiewicz a0456399fb usb: gadget: configfs: don't NUL-terminate (sub)compatible ids
The "Extended Compat ID OS Feature Descriptor Specification" does not
require the (sub)compatible ids to be NUL-terminated, because they
are placed in a fixed-size buffer and only unused parts of it should
contain NULs. If the buffer is fully utilized, there is no place for NULs.

Consequently, the code which uses desc->ext_compat_id never expects the
data contained to be NUL terminated.

If the compatible id is stored after sub-compatible id, and the compatible
id is full length (8 bytes), the (useless) NUL terminator overwrites the
first byte of the sub-compatible id.

If the sub-compatible id is full length (8 bytes), the (useless) NUL
terminator ends up out of the buffer. The situation can happen in the RNDIS
function, where the buffer is a part of struct f_rndis_opts. The next
member of struct f_rndis_opts is a mutex, so its first byte gets
overwritten. The said byte is a part of a mutex'es member which contains
the information on whether the muext is locked or not. This can lead to a
deadlock, because, in a configfs-composed gadget when a function is linked
into a configuration with config_usb_cfg_link(), usb_get_function()
is called, which then calls rndis_alloc(), which tries locking the same
mutex and (wrongly) finds it already locked.

This patch eliminates NUL terminating of the (sub)compatible id.

Cc: <stable@vger.kernel.org> # v3.16+
Fixes: da4243145f: "usb: gadget: configfs: OS Extended Compatibility descriptors support"
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
2015-02-23 09:37:27 -06:00

1575 lines
38 KiB
C

#include <linux/configfs.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/nls.h>
#include <linux/usb/composite.h>
#include <linux/usb/gadget_configfs.h>
#include "configfs.h"
#include "u_f.h"
#include "u_os_desc.h"
int check_user_usb_string(const char *name,
struct usb_gadget_strings *stringtab_dev)
{
unsigned primary_lang;
unsigned sub_lang;
u16 num;
int ret;
ret = kstrtou16(name, 0, &num);
if (ret)
return ret;
primary_lang = num & 0x3ff;
sub_lang = num >> 10;
/* simple sanity check for valid langid */
switch (primary_lang) {
case 0:
case 0x62 ... 0xfe:
case 0x100 ... 0x3ff:
return -EINVAL;
}
if (!sub_lang)
return -EINVAL;
stringtab_dev->language = num;
return 0;
}
#define MAX_NAME_LEN 40
#define MAX_USB_STRING_LANGS 2
struct gadget_info {
struct config_group group;
struct config_group functions_group;
struct config_group configs_group;
struct config_group strings_group;
struct config_group os_desc_group;
struct config_group *default_groups[5];
struct mutex lock;
struct usb_gadget_strings *gstrings[MAX_USB_STRING_LANGS + 1];
struct list_head string_list;
struct list_head available_func;
const char *udc_name;
#ifdef CONFIG_USB_OTG
struct usb_otg_descriptor otg;
#endif
struct usb_composite_driver composite;
struct usb_composite_dev cdev;
bool use_os_desc;
char b_vendor_code;
char qw_sign[OS_STRING_QW_SIGN_LEN];
};
struct config_usb_cfg {
struct config_group group;
struct config_group strings_group;
struct config_group *default_groups[2];
struct list_head string_list;
struct usb_configuration c;
struct list_head func_list;
struct usb_gadget_strings *gstrings[MAX_USB_STRING_LANGS + 1];
};
struct gadget_strings {
struct usb_gadget_strings stringtab_dev;
struct usb_string strings[USB_GADGET_FIRST_AVAIL_IDX];
char *manufacturer;
char *product;
char *serialnumber;
struct config_group group;
struct list_head list;
};
struct os_desc {
struct config_group group;
};
struct gadget_config_name {
struct usb_gadget_strings stringtab_dev;
struct usb_string strings;
char *configuration;
struct config_group group;
struct list_head list;
};
static int usb_string_copy(const char *s, char **s_copy)
{
int ret;
char *str;
char *copy = *s_copy;
ret = strlen(s);
if (ret > 126)
return -EOVERFLOW;
str = kstrdup(s, GFP_KERNEL);
if (!str)
return -ENOMEM;
if (str[ret - 1] == '\n')
str[ret - 1] = '\0';
kfree(copy);
*s_copy = str;
return 0;
}
CONFIGFS_ATTR_STRUCT(gadget_info);
CONFIGFS_ATTR_STRUCT(config_usb_cfg);
#define GI_DEVICE_DESC_ITEM_ATTR(name) \
static struct gadget_info_attribute gadget_cdev_desc_##name = \
__CONFIGFS_ATTR(name, S_IRUGO | S_IWUSR, \
gadget_dev_desc_##name##_show, \
gadget_dev_desc_##name##_store)
#define GI_DEVICE_DESC_SIMPLE_R_u8(__name) \
static ssize_t gadget_dev_desc_##__name##_show(struct gadget_info *gi, \
char *page) \
{ \
return sprintf(page, "0x%02x\n", gi->cdev.desc.__name); \
}
#define GI_DEVICE_DESC_SIMPLE_R_u16(__name) \
static ssize_t gadget_dev_desc_##__name##_show(struct gadget_info *gi, \
char *page) \
{ \
return sprintf(page, "0x%04x\n", le16_to_cpup(&gi->cdev.desc.__name)); \
}
#define GI_DEVICE_DESC_SIMPLE_W_u8(_name) \
static ssize_t gadget_dev_desc_##_name##_store(struct gadget_info *gi, \
const char *page, size_t len) \
{ \
u8 val; \
int ret; \
ret = kstrtou8(page, 0, &val); \
if (ret) \
return ret; \
gi->cdev.desc._name = val; \
return len; \
}
#define GI_DEVICE_DESC_SIMPLE_W_u16(_name) \
static ssize_t gadget_dev_desc_##_name##_store(struct gadget_info *gi, \
const char *page, size_t len) \
{ \
u16 val; \
int ret; \
ret = kstrtou16(page, 0, &val); \
if (ret) \
return ret; \
gi->cdev.desc._name = cpu_to_le16p(&val); \
return len; \
}
#define GI_DEVICE_DESC_SIMPLE_RW(_name, _type) \
GI_DEVICE_DESC_SIMPLE_R_##_type(_name) \
GI_DEVICE_DESC_SIMPLE_W_##_type(_name)
GI_DEVICE_DESC_SIMPLE_R_u16(bcdUSB);
GI_DEVICE_DESC_SIMPLE_RW(bDeviceClass, u8);
GI_DEVICE_DESC_SIMPLE_RW(bDeviceSubClass, u8);
GI_DEVICE_DESC_SIMPLE_RW(bDeviceProtocol, u8);
GI_DEVICE_DESC_SIMPLE_RW(bMaxPacketSize0, u8);
GI_DEVICE_DESC_SIMPLE_RW(idVendor, u16);
GI_DEVICE_DESC_SIMPLE_RW(idProduct, u16);
GI_DEVICE_DESC_SIMPLE_R_u16(bcdDevice);
static ssize_t is_valid_bcd(u16 bcd_val)
{
if ((bcd_val & 0xf) > 9)
return -EINVAL;
if (((bcd_val >> 4) & 0xf) > 9)
return -EINVAL;
if (((bcd_val >> 8) & 0xf) > 9)
return -EINVAL;
if (((bcd_val >> 12) & 0xf) > 9)
return -EINVAL;
return 0;
}
static ssize_t gadget_dev_desc_bcdDevice_store(struct gadget_info *gi,
const char *page, size_t len)
{
u16 bcdDevice;
int ret;
ret = kstrtou16(page, 0, &bcdDevice);
if (ret)
return ret;
ret = is_valid_bcd(bcdDevice);
if (ret)
return ret;
gi->cdev.desc.bcdDevice = cpu_to_le16(bcdDevice);
return len;
}
static ssize_t gadget_dev_desc_bcdUSB_store(struct gadget_info *gi,
const char *page, size_t len)
{
u16 bcdUSB;
int ret;
ret = kstrtou16(page, 0, &bcdUSB);
if (ret)
return ret;
ret = is_valid_bcd(bcdUSB);
if (ret)
return ret;
gi->cdev.desc.bcdUSB = cpu_to_le16(bcdUSB);
return len;
}
static ssize_t gadget_dev_desc_UDC_show(struct gadget_info *gi, char *page)
{
return sprintf(page, "%s\n", gi->udc_name ?: "");
}
static int unregister_gadget(struct gadget_info *gi)
{
int ret;
if (!gi->udc_name)
return -ENODEV;
ret = usb_gadget_unregister_driver(&gi->composite.gadget_driver);
if (ret)
return ret;
kfree(gi->udc_name);
gi->udc_name = NULL;
return 0;
}
static ssize_t gadget_dev_desc_UDC_store(struct gadget_info *gi,
const char *page, size_t len)
{
char *name;
int ret;
name = kstrdup(page, GFP_KERNEL);
if (!name)
return -ENOMEM;
if (name[len - 1] == '\n')
name[len - 1] = '\0';
mutex_lock(&gi->lock);
if (!strlen(name)) {
ret = unregister_gadget(gi);
if (ret)
goto err;
} else {
if (gi->udc_name) {
ret = -EBUSY;
goto err;
}
ret = usb_udc_attach_driver(name, &gi->composite.gadget_driver);
if (ret)
goto err;
gi->udc_name = name;
}
mutex_unlock(&gi->lock);
return len;
err:
kfree(name);
mutex_unlock(&gi->lock);
return ret;
}
GI_DEVICE_DESC_ITEM_ATTR(bDeviceClass);
GI_DEVICE_DESC_ITEM_ATTR(bDeviceSubClass);
GI_DEVICE_DESC_ITEM_ATTR(bDeviceProtocol);
GI_DEVICE_DESC_ITEM_ATTR(bMaxPacketSize0);
GI_DEVICE_DESC_ITEM_ATTR(idVendor);
GI_DEVICE_DESC_ITEM_ATTR(idProduct);
GI_DEVICE_DESC_ITEM_ATTR(bcdDevice);
GI_DEVICE_DESC_ITEM_ATTR(bcdUSB);
GI_DEVICE_DESC_ITEM_ATTR(UDC);
static struct configfs_attribute *gadget_root_attrs[] = {
&gadget_cdev_desc_bDeviceClass.attr,
&gadget_cdev_desc_bDeviceSubClass.attr,
&gadget_cdev_desc_bDeviceProtocol.attr,
&gadget_cdev_desc_bMaxPacketSize0.attr,
&gadget_cdev_desc_idVendor.attr,
&gadget_cdev_desc_idProduct.attr,
&gadget_cdev_desc_bcdDevice.attr,
&gadget_cdev_desc_bcdUSB.attr,
&gadget_cdev_desc_UDC.attr,
NULL,
};
static inline struct gadget_info *to_gadget_info(struct config_item *item)
{
return container_of(to_config_group(item), struct gadget_info, group);
}
static inline struct gadget_strings *to_gadget_strings(struct config_item *item)
{
return container_of(to_config_group(item), struct gadget_strings,
group);
}
static inline struct gadget_config_name *to_gadget_config_name(
struct config_item *item)
{
return container_of(to_config_group(item), struct gadget_config_name,
group);
}
static inline struct config_usb_cfg *to_config_usb_cfg(struct config_item *item)
{
return container_of(to_config_group(item), struct config_usb_cfg,
group);
}
static inline struct usb_function_instance *to_usb_function_instance(
struct config_item *item)
{
return container_of(to_config_group(item),
struct usb_function_instance, group);
}
static void gadget_info_attr_release(struct config_item *item)
{
struct gadget_info *gi = to_gadget_info(item);
WARN_ON(!list_empty(&gi->cdev.configs));
WARN_ON(!list_empty(&gi->string_list));
WARN_ON(!list_empty(&gi->available_func));
kfree(gi->composite.gadget_driver.function);
kfree(gi);
}
CONFIGFS_ATTR_OPS(gadget_info);
static struct configfs_item_operations gadget_root_item_ops = {
.release = gadget_info_attr_release,
.show_attribute = gadget_info_attr_show,
.store_attribute = gadget_info_attr_store,
};
static void gadget_config_attr_release(struct config_item *item)
{
struct config_usb_cfg *cfg = to_config_usb_cfg(item);
WARN_ON(!list_empty(&cfg->c.functions));
list_del(&cfg->c.list);
kfree(cfg->c.label);
kfree(cfg);
}
static int config_usb_cfg_link(
struct config_item *usb_cfg_ci,
struct config_item *usb_func_ci)
{
struct config_usb_cfg *cfg = to_config_usb_cfg(usb_cfg_ci);
struct usb_composite_dev *cdev = cfg->c.cdev;
struct gadget_info *gi = container_of(cdev, struct gadget_info, cdev);
struct config_group *group = to_config_group(usb_func_ci);
struct usb_function_instance *fi = container_of(group,
struct usb_function_instance, group);
struct usb_function_instance *a_fi;
struct usb_function *f;
int ret;
mutex_lock(&gi->lock);
/*
* Make sure this function is from within our _this_ gadget and not
* from another gadget or a random directory.
* Also a function instance can only be linked once.
*/
list_for_each_entry(a_fi, &gi->available_func, cfs_list) {
if (a_fi == fi)
break;
}
if (a_fi != fi) {
ret = -EINVAL;
goto out;
}
list_for_each_entry(f, &cfg->func_list, list) {
if (f->fi == fi) {
ret = -EEXIST;
goto out;
}
}
f = usb_get_function(fi);
if (IS_ERR(f)) {
ret = PTR_ERR(f);
goto out;
}
/* stash the function until we bind it to the gadget */
list_add_tail(&f->list, &cfg->func_list);
ret = 0;
out:
mutex_unlock(&gi->lock);
return ret;
}
static int config_usb_cfg_unlink(
struct config_item *usb_cfg_ci,
struct config_item *usb_func_ci)
{
struct config_usb_cfg *cfg = to_config_usb_cfg(usb_cfg_ci);
struct usb_composite_dev *cdev = cfg->c.cdev;
struct gadget_info *gi = container_of(cdev, struct gadget_info, cdev);
struct config_group *group = to_config_group(usb_func_ci);
struct usb_function_instance *fi = container_of(group,
struct usb_function_instance, group);
struct usb_function *f;
/*
* ideally I would like to forbid to unlink functions while a gadget is
* bound to an UDC. Since this isn't possible at the moment, we simply
* force an unbind, the function is available here and then we can
* remove the function.
*/
mutex_lock(&gi->lock);
if (gi->udc_name)
unregister_gadget(gi);
WARN_ON(gi->udc_name);
list_for_each_entry(f, &cfg->func_list, list) {
if (f->fi == fi) {
list_del(&f->list);
usb_put_function(f);
mutex_unlock(&gi->lock);
return 0;
}
}
mutex_unlock(&gi->lock);
WARN(1, "Unable to locate function to unbind\n");
return 0;
}
CONFIGFS_ATTR_OPS(config_usb_cfg);
static struct configfs_item_operations gadget_config_item_ops = {
.release = gadget_config_attr_release,
.show_attribute = config_usb_cfg_attr_show,
.store_attribute = config_usb_cfg_attr_store,
.allow_link = config_usb_cfg_link,
.drop_link = config_usb_cfg_unlink,
};
static ssize_t gadget_config_desc_MaxPower_show(struct config_usb_cfg *cfg,
char *page)
{
return sprintf(page, "%u\n", cfg->c.MaxPower);
}
static ssize_t gadget_config_desc_MaxPower_store(struct config_usb_cfg *cfg,
const char *page, size_t len)
{
u16 val;
int ret;
ret = kstrtou16(page, 0, &val);
if (ret)
return ret;
if (DIV_ROUND_UP(val, 8) > 0xff)
return -ERANGE;
cfg->c.MaxPower = val;
return len;
}
static ssize_t gadget_config_desc_bmAttributes_show(struct config_usb_cfg *cfg,
char *page)
{
return sprintf(page, "0x%02x\n", cfg->c.bmAttributes);
}
static ssize_t gadget_config_desc_bmAttributes_store(struct config_usb_cfg *cfg,
const char *page, size_t len)
{
u8 val;
int ret;
ret = kstrtou8(page, 0, &val);
if (ret)
return ret;
if (!(val & USB_CONFIG_ATT_ONE))
return -EINVAL;
if (val & ~(USB_CONFIG_ATT_ONE | USB_CONFIG_ATT_SELFPOWER |
USB_CONFIG_ATT_WAKEUP))
return -EINVAL;
cfg->c.bmAttributes = val;
return len;
}
#define CFG_CONFIG_DESC_ITEM_ATTR(name) \
static struct config_usb_cfg_attribute gadget_usb_cfg_##name = \
__CONFIGFS_ATTR(name, S_IRUGO | S_IWUSR, \
gadget_config_desc_##name##_show, \
gadget_config_desc_##name##_store)
CFG_CONFIG_DESC_ITEM_ATTR(MaxPower);
CFG_CONFIG_DESC_ITEM_ATTR(bmAttributes);
static struct configfs_attribute *gadget_config_attrs[] = {
&gadget_usb_cfg_MaxPower.attr,
&gadget_usb_cfg_bmAttributes.attr,
NULL,
};
static struct config_item_type gadget_config_type = {
.ct_item_ops = &gadget_config_item_ops,
.ct_attrs = gadget_config_attrs,
.ct_owner = THIS_MODULE,
};
static struct config_item_type gadget_root_type = {
.ct_item_ops = &gadget_root_item_ops,
.ct_attrs = gadget_root_attrs,
.ct_owner = THIS_MODULE,
};
static void composite_init_dev(struct usb_composite_dev *cdev)
{
spin_lock_init(&cdev->lock);
INIT_LIST_HEAD(&cdev->configs);
INIT_LIST_HEAD(&cdev->gstrings);
}
static struct config_group *function_make(
struct config_group *group,
const char *name)
{
struct gadget_info *gi;
struct usb_function_instance *fi;
char buf[MAX_NAME_LEN];
char *func_name;
char *instance_name;
int ret;
ret = snprintf(buf, MAX_NAME_LEN, "%s", name);
if (ret >= MAX_NAME_LEN)
return ERR_PTR(-ENAMETOOLONG);
func_name = buf;
instance_name = strchr(func_name, '.');
if (!instance_name) {
pr_err("Unable to locate . in FUNC.INSTANCE\n");
return ERR_PTR(-EINVAL);
}
*instance_name = '\0';
instance_name++;
fi = usb_get_function_instance(func_name);
if (IS_ERR(fi))
return ERR_CAST(fi);
ret = config_item_set_name(&fi->group.cg_item, name);
if (ret) {
usb_put_function_instance(fi);
return ERR_PTR(ret);
}
if (fi->set_inst_name) {
ret = fi->set_inst_name(fi, instance_name);
if (ret) {
usb_put_function_instance(fi);
return ERR_PTR(ret);
}
}
gi = container_of(group, struct gadget_info, functions_group);
mutex_lock(&gi->lock);
list_add_tail(&fi->cfs_list, &gi->available_func);
mutex_unlock(&gi->lock);
return &fi->group;
}
static void function_drop(
struct config_group *group,
struct config_item *item)
{
struct usb_function_instance *fi = to_usb_function_instance(item);
struct gadget_info *gi;
gi = container_of(group, struct gadget_info, functions_group);
mutex_lock(&gi->lock);
list_del(&fi->cfs_list);
mutex_unlock(&gi->lock);
config_item_put(item);
}
static struct configfs_group_operations functions_ops = {
.make_group = &function_make,
.drop_item = &function_drop,
};
static struct config_item_type functions_type = {
.ct_group_ops = &functions_ops,
.ct_owner = THIS_MODULE,
};
CONFIGFS_ATTR_STRUCT(gadget_config_name);
GS_STRINGS_RW(gadget_config_name, configuration);
static struct configfs_attribute *gadget_config_name_langid_attrs[] = {
&gadget_config_name_configuration.attr,
NULL,
};
static void gadget_config_name_attr_release(struct config_item *item)
{
struct gadget_config_name *cn = to_gadget_config_name(item);
kfree(cn->configuration);
list_del(&cn->list);
kfree(cn);
}
USB_CONFIG_STRING_RW_OPS(gadget_config_name);
USB_CONFIG_STRINGS_LANG(gadget_config_name, config_usb_cfg);
static struct config_group *config_desc_make(
struct config_group *group,
const char *name)
{
struct gadget_info *gi;
struct config_usb_cfg *cfg;
char buf[MAX_NAME_LEN];
char *num_str;
u8 num;
int ret;
gi = container_of(group, struct gadget_info, configs_group);
ret = snprintf(buf, MAX_NAME_LEN, "%s", name);
if (ret >= MAX_NAME_LEN)
return ERR_PTR(-ENAMETOOLONG);
num_str = strchr(buf, '.');
if (!num_str) {
pr_err("Unable to locate . in name.bConfigurationValue\n");
return ERR_PTR(-EINVAL);
}
*num_str = '\0';
num_str++;
if (!strlen(buf))
return ERR_PTR(-EINVAL);
ret = kstrtou8(num_str, 0, &num);
if (ret)
return ERR_PTR(ret);
cfg = kzalloc(sizeof(*cfg), GFP_KERNEL);
if (!cfg)
return ERR_PTR(-ENOMEM);
cfg->c.label = kstrdup(buf, GFP_KERNEL);
if (!cfg->c.label) {
ret = -ENOMEM;
goto err;
}
cfg->c.bConfigurationValue = num;
cfg->c.MaxPower = CONFIG_USB_GADGET_VBUS_DRAW;
cfg->c.bmAttributes = USB_CONFIG_ATT_ONE;
INIT_LIST_HEAD(&cfg->string_list);
INIT_LIST_HEAD(&cfg->func_list);
cfg->group.default_groups = cfg->default_groups;
cfg->default_groups[0] = &cfg->strings_group;
config_group_init_type_name(&cfg->group, name,
&gadget_config_type);
config_group_init_type_name(&cfg->strings_group, "strings",
&gadget_config_name_strings_type);
ret = usb_add_config_only(&gi->cdev, &cfg->c);
if (ret)
goto err;
return &cfg->group;
err:
kfree(cfg->c.label);
kfree(cfg);
return ERR_PTR(ret);
}
static void config_desc_drop(
struct config_group *group,
struct config_item *item)
{
config_item_put(item);
}
static struct configfs_group_operations config_desc_ops = {
.make_group = &config_desc_make,
.drop_item = &config_desc_drop,
};
static struct config_item_type config_desc_type = {
.ct_group_ops = &config_desc_ops,
.ct_owner = THIS_MODULE,
};
CONFIGFS_ATTR_STRUCT(gadget_strings);
GS_STRINGS_RW(gadget_strings, manufacturer);
GS_STRINGS_RW(gadget_strings, product);
GS_STRINGS_RW(gadget_strings, serialnumber);
static struct configfs_attribute *gadget_strings_langid_attrs[] = {
&gadget_strings_manufacturer.attr,
&gadget_strings_product.attr,
&gadget_strings_serialnumber.attr,
NULL,
};
static void gadget_strings_attr_release(struct config_item *item)
{
struct gadget_strings *gs = to_gadget_strings(item);
kfree(gs->manufacturer);
kfree(gs->product);
kfree(gs->serialnumber);
list_del(&gs->list);
kfree(gs);
}
USB_CONFIG_STRING_RW_OPS(gadget_strings);
USB_CONFIG_STRINGS_LANG(gadget_strings, gadget_info);
static inline struct os_desc *to_os_desc(struct config_item *item)
{
return container_of(to_config_group(item), struct os_desc, group);
}
CONFIGFS_ATTR_STRUCT(os_desc);
CONFIGFS_ATTR_OPS(os_desc);
static ssize_t os_desc_use_show(struct os_desc *os_desc, char *page)
{
struct gadget_info *gi;
gi = to_gadget_info(os_desc->group.cg_item.ci_parent);
return sprintf(page, "%d", gi->use_os_desc);
}
static ssize_t os_desc_use_store(struct os_desc *os_desc, const char *page,
size_t len)
{
struct gadget_info *gi;
int ret;
bool use;
gi = to_gadget_info(os_desc->group.cg_item.ci_parent);
mutex_lock(&gi->lock);
ret = strtobool(page, &use);
if (!ret) {
gi->use_os_desc = use;
ret = len;
}
mutex_unlock(&gi->lock);
return ret;
}
static struct os_desc_attribute os_desc_use =
__CONFIGFS_ATTR(use, S_IRUGO | S_IWUSR,
os_desc_use_show,
os_desc_use_store);
static ssize_t os_desc_b_vendor_code_show(struct os_desc *os_desc, char *page)
{
struct gadget_info *gi;
gi = to_gadget_info(os_desc->group.cg_item.ci_parent);
return sprintf(page, "%d", gi->b_vendor_code);
}
static ssize_t os_desc_b_vendor_code_store(struct os_desc *os_desc,
const char *page, size_t len)
{
struct gadget_info *gi;
int ret;
u8 b_vendor_code;
gi = to_gadget_info(os_desc->group.cg_item.ci_parent);
mutex_lock(&gi->lock);
ret = kstrtou8(page, 0, &b_vendor_code);
if (!ret) {
gi->b_vendor_code = b_vendor_code;
ret = len;
}
mutex_unlock(&gi->lock);
return ret;
}
static struct os_desc_attribute os_desc_b_vendor_code =
__CONFIGFS_ATTR(b_vendor_code, S_IRUGO | S_IWUSR,
os_desc_b_vendor_code_show,
os_desc_b_vendor_code_store);
static ssize_t os_desc_qw_sign_show(struct os_desc *os_desc, char *page)
{
struct gadget_info *gi;
gi = to_gadget_info(os_desc->group.cg_item.ci_parent);
memcpy(page, gi->qw_sign, OS_STRING_QW_SIGN_LEN);
return OS_STRING_QW_SIGN_LEN;
}
static ssize_t os_desc_qw_sign_store(struct os_desc *os_desc, const char *page,
size_t len)
{
struct gadget_info *gi;
int res, l;
gi = to_gadget_info(os_desc->group.cg_item.ci_parent);
l = min((int)len, OS_STRING_QW_SIGN_LEN >> 1);
if (page[l - 1] == '\n')
--l;
mutex_lock(&gi->lock);
res = utf8s_to_utf16s(page, l,
UTF16_LITTLE_ENDIAN, (wchar_t *) gi->qw_sign,
OS_STRING_QW_SIGN_LEN);
if (res > 0)
res = len;
mutex_unlock(&gi->lock);
return res;
}
static struct os_desc_attribute os_desc_qw_sign =
__CONFIGFS_ATTR(qw_sign, S_IRUGO | S_IWUSR,
os_desc_qw_sign_show,
os_desc_qw_sign_store);
static struct configfs_attribute *os_desc_attrs[] = {
&os_desc_use.attr,
&os_desc_b_vendor_code.attr,
&os_desc_qw_sign.attr,
NULL,
};
static void os_desc_attr_release(struct config_item *item)
{
struct os_desc *os_desc = to_os_desc(item);
kfree(os_desc);
}
static int os_desc_link(struct config_item *os_desc_ci,
struct config_item *usb_cfg_ci)
{
struct gadget_info *gi = container_of(to_config_group(os_desc_ci),
struct gadget_info, os_desc_group);
struct usb_composite_dev *cdev = &gi->cdev;
struct config_usb_cfg *c_target =
container_of(to_config_group(usb_cfg_ci),
struct config_usb_cfg, group);
struct usb_configuration *c;
int ret;
mutex_lock(&gi->lock);
list_for_each_entry(c, &cdev->configs, list) {
if (c == &c_target->c)
break;
}
if (c != &c_target->c) {
ret = -EINVAL;
goto out;
}
if (cdev->os_desc_config) {
ret = -EBUSY;
goto out;
}
cdev->os_desc_config = &c_target->c;
ret = 0;
out:
mutex_unlock(&gi->lock);
return ret;
}
static int os_desc_unlink(struct config_item *os_desc_ci,
struct config_item *usb_cfg_ci)
{
struct gadget_info *gi = container_of(to_config_group(os_desc_ci),
struct gadget_info, os_desc_group);
struct usb_composite_dev *cdev = &gi->cdev;
mutex_lock(&gi->lock);
if (gi->udc_name)
unregister_gadget(gi);
cdev->os_desc_config = NULL;
WARN_ON(gi->udc_name);
mutex_unlock(&gi->lock);
return 0;
}
static struct configfs_item_operations os_desc_ops = {
.release = os_desc_attr_release,
.show_attribute = os_desc_attr_show,
.store_attribute = os_desc_attr_store,
.allow_link = os_desc_link,
.drop_link = os_desc_unlink,
};
static struct config_item_type os_desc_type = {
.ct_item_ops = &os_desc_ops,
.ct_attrs = os_desc_attrs,
.ct_owner = THIS_MODULE,
};
CONFIGFS_ATTR_STRUCT(usb_os_desc);
CONFIGFS_ATTR_OPS(usb_os_desc);
static inline struct usb_os_desc_ext_prop
*to_usb_os_desc_ext_prop(struct config_item *item)
{
return container_of(item, struct usb_os_desc_ext_prop, item);
}
CONFIGFS_ATTR_STRUCT(usb_os_desc_ext_prop);
CONFIGFS_ATTR_OPS(usb_os_desc_ext_prop);
static ssize_t ext_prop_type_show(struct usb_os_desc_ext_prop *ext_prop,
char *page)
{
return sprintf(page, "%d", ext_prop->type);
}
static ssize_t ext_prop_type_store(struct usb_os_desc_ext_prop *ext_prop,
const char *page, size_t len)
{
struct usb_os_desc *desc = to_usb_os_desc(ext_prop->item.ci_parent);
u8 type;
int ret;
if (desc->opts_mutex)
mutex_lock(desc->opts_mutex);
ret = kstrtou8(page, 0, &type);
if (ret)
goto end;
if (type < USB_EXT_PROP_UNICODE || type > USB_EXT_PROP_UNICODE_MULTI) {
ret = -EINVAL;
goto end;
}
if ((ext_prop->type == USB_EXT_PROP_BINARY ||
ext_prop->type == USB_EXT_PROP_LE32 ||
ext_prop->type == USB_EXT_PROP_BE32) &&
(type == USB_EXT_PROP_UNICODE ||
type == USB_EXT_PROP_UNICODE_ENV ||
type == USB_EXT_PROP_UNICODE_LINK))
ext_prop->data_len <<= 1;
else if ((ext_prop->type == USB_EXT_PROP_UNICODE ||
ext_prop->type == USB_EXT_PROP_UNICODE_ENV ||
ext_prop->type == USB_EXT_PROP_UNICODE_LINK) &&
(type == USB_EXT_PROP_BINARY ||
type == USB_EXT_PROP_LE32 ||
type == USB_EXT_PROP_BE32))
ext_prop->data_len >>= 1;
ext_prop->type = type;
ret = len;
end:
if (desc->opts_mutex)
mutex_unlock(desc->opts_mutex);
return ret;
}
static ssize_t ext_prop_data_show(struct usb_os_desc_ext_prop *ext_prop,
char *page)
{
int len = ext_prop->data_len;
if (ext_prop->type == USB_EXT_PROP_UNICODE ||
ext_prop->type == USB_EXT_PROP_UNICODE_ENV ||
ext_prop->type == USB_EXT_PROP_UNICODE_LINK)
len >>= 1;
memcpy(page, ext_prop->data, len);
return len;
}
static ssize_t ext_prop_data_store(struct usb_os_desc_ext_prop *ext_prop,
const char *page, size_t len)
{
struct usb_os_desc *desc = to_usb_os_desc(ext_prop->item.ci_parent);
char *new_data;
size_t ret_len = len;
if (page[len - 1] == '\n' || page[len - 1] == '\0')
--len;
new_data = kmemdup(page, len, GFP_KERNEL);
if (!new_data)
return -ENOMEM;
if (desc->opts_mutex)
mutex_lock(desc->opts_mutex);
kfree(ext_prop->data);
ext_prop->data = new_data;
desc->ext_prop_len -= ext_prop->data_len;
ext_prop->data_len = len;
desc->ext_prop_len += ext_prop->data_len;
if (ext_prop->type == USB_EXT_PROP_UNICODE ||
ext_prop->type == USB_EXT_PROP_UNICODE_ENV ||
ext_prop->type == USB_EXT_PROP_UNICODE_LINK) {
desc->ext_prop_len -= ext_prop->data_len;
ext_prop->data_len <<= 1;
ext_prop->data_len += 2;
desc->ext_prop_len += ext_prop->data_len;
}
if (desc->opts_mutex)
mutex_unlock(desc->opts_mutex);
return ret_len;
}
static struct usb_os_desc_ext_prop_attribute ext_prop_type =
__CONFIGFS_ATTR(type, S_IRUGO | S_IWUSR,
ext_prop_type_show, ext_prop_type_store);
static struct usb_os_desc_ext_prop_attribute ext_prop_data =
__CONFIGFS_ATTR(data, S_IRUGO | S_IWUSR,
ext_prop_data_show, ext_prop_data_store);
static struct configfs_attribute *ext_prop_attrs[] = {
&ext_prop_type.attr,
&ext_prop_data.attr,
NULL,
};
static void usb_os_desc_ext_prop_release(struct config_item *item)
{
struct usb_os_desc_ext_prop *ext_prop = to_usb_os_desc_ext_prop(item);
kfree(ext_prop); /* frees a whole chunk */
}
static struct configfs_item_operations ext_prop_ops = {
.release = usb_os_desc_ext_prop_release,
.show_attribute = usb_os_desc_ext_prop_attr_show,
.store_attribute = usb_os_desc_ext_prop_attr_store,
};
static struct config_item *ext_prop_make(
struct config_group *group,
const char *name)
{
struct usb_os_desc_ext_prop *ext_prop;
struct config_item_type *ext_prop_type;
struct usb_os_desc *desc;
char *vlabuf;
vla_group(data_chunk);
vla_item(data_chunk, struct usb_os_desc_ext_prop, ext_prop, 1);
vla_item(data_chunk, struct config_item_type, ext_prop_type, 1);
vlabuf = kzalloc(vla_group_size(data_chunk), GFP_KERNEL);
if (!vlabuf)
return ERR_PTR(-ENOMEM);
ext_prop = vla_ptr(vlabuf, data_chunk, ext_prop);
ext_prop_type = vla_ptr(vlabuf, data_chunk, ext_prop_type);
desc = container_of(group, struct usb_os_desc, group);
ext_prop_type->ct_item_ops = &ext_prop_ops;
ext_prop_type->ct_attrs = ext_prop_attrs;
ext_prop_type->ct_owner = desc->owner;
config_item_init_type_name(&ext_prop->item, name, ext_prop_type);
ext_prop->name = kstrdup(name, GFP_KERNEL);
if (!ext_prop->name) {
kfree(vlabuf);
return ERR_PTR(-ENOMEM);
}
desc->ext_prop_len += 14;
ext_prop->name_len = 2 * strlen(ext_prop->name) + 2;
if (desc->opts_mutex)
mutex_lock(desc->opts_mutex);
desc->ext_prop_len += ext_prop->name_len;
list_add_tail(&ext_prop->entry, &desc->ext_prop);
++desc->ext_prop_count;
if (desc->opts_mutex)
mutex_unlock(desc->opts_mutex);
return &ext_prop->item;
}
static void ext_prop_drop(struct config_group *group, struct config_item *item)
{
struct usb_os_desc_ext_prop *ext_prop = to_usb_os_desc_ext_prop(item);
struct usb_os_desc *desc = to_usb_os_desc(&group->cg_item);
if (desc->opts_mutex)
mutex_lock(desc->opts_mutex);
list_del(&ext_prop->entry);
--desc->ext_prop_count;
kfree(ext_prop->name);
desc->ext_prop_len -= (ext_prop->name_len + ext_prop->data_len + 14);
if (desc->opts_mutex)
mutex_unlock(desc->opts_mutex);
config_item_put(item);
}
static struct configfs_group_operations interf_grp_ops = {
.make_item = &ext_prop_make,
.drop_item = &ext_prop_drop,
};
static struct configfs_item_operations interf_item_ops = {
.show_attribute = usb_os_desc_attr_show,
.store_attribute = usb_os_desc_attr_store,
};
static ssize_t interf_grp_compatible_id_show(struct usb_os_desc *desc,
char *page)
{
memcpy(page, desc->ext_compat_id, 8);
return 8;
}
static ssize_t interf_grp_compatible_id_store(struct usb_os_desc *desc,
const char *page, size_t len)
{
int l;
l = min_t(int, 8, len);
if (page[l - 1] == '\n')
--l;
if (desc->opts_mutex)
mutex_lock(desc->opts_mutex);
memcpy(desc->ext_compat_id, page, l);
if (desc->opts_mutex)
mutex_unlock(desc->opts_mutex);
return len;
}
static struct usb_os_desc_attribute interf_grp_attr_compatible_id =
__CONFIGFS_ATTR(compatible_id, S_IRUGO | S_IWUSR,
interf_grp_compatible_id_show,
interf_grp_compatible_id_store);
static ssize_t interf_grp_sub_compatible_id_show(struct usb_os_desc *desc,
char *page)
{
memcpy(page, desc->ext_compat_id + 8, 8);
return 8;
}
static ssize_t interf_grp_sub_compatible_id_store(struct usb_os_desc *desc,
const char *page, size_t len)
{
int l;
l = min_t(int, 8, len);
if (page[l - 1] == '\n')
--l;
if (desc->opts_mutex)
mutex_lock(desc->opts_mutex);
memcpy(desc->ext_compat_id + 8, page, l);
if (desc->opts_mutex)
mutex_unlock(desc->opts_mutex);
return len;
}
static struct usb_os_desc_attribute interf_grp_attr_sub_compatible_id =
__CONFIGFS_ATTR(sub_compatible_id, S_IRUGO | S_IWUSR,
interf_grp_sub_compatible_id_show,
interf_grp_sub_compatible_id_store);
static struct configfs_attribute *interf_grp_attrs[] = {
&interf_grp_attr_compatible_id.attr,
&interf_grp_attr_sub_compatible_id.attr,
NULL
};
int usb_os_desc_prepare_interf_dir(struct config_group *parent,
int n_interf,
struct usb_os_desc **desc,
char **names,
struct module *owner)
{
struct config_group **f_default_groups, *os_desc_group,
**interface_groups;
struct config_item_type *os_desc_type, *interface_type;
vla_group(data_chunk);
vla_item(data_chunk, struct config_group *, f_default_groups, 2);
vla_item(data_chunk, struct config_group, os_desc_group, 1);
vla_item(data_chunk, struct config_group *, interface_groups,
n_interf + 1);
vla_item(data_chunk, struct config_item_type, os_desc_type, 1);
vla_item(data_chunk, struct config_item_type, interface_type, 1);
char *vlabuf = kzalloc(vla_group_size(data_chunk), GFP_KERNEL);
if (!vlabuf)
return -ENOMEM;
f_default_groups = vla_ptr(vlabuf, data_chunk, f_default_groups);
os_desc_group = vla_ptr(vlabuf, data_chunk, os_desc_group);
os_desc_type = vla_ptr(vlabuf, data_chunk, os_desc_type);
interface_groups = vla_ptr(vlabuf, data_chunk, interface_groups);
interface_type = vla_ptr(vlabuf, data_chunk, interface_type);
parent->default_groups = f_default_groups;
os_desc_type->ct_owner = owner;
config_group_init_type_name(os_desc_group, "os_desc", os_desc_type);
f_default_groups[0] = os_desc_group;
os_desc_group->default_groups = interface_groups;
interface_type->ct_item_ops = &interf_item_ops;
interface_type->ct_group_ops = &interf_grp_ops;
interface_type->ct_attrs = interf_grp_attrs;
interface_type->ct_owner = owner;
while (n_interf--) {
struct usb_os_desc *d;
d = desc[n_interf];
d->owner = owner;
config_group_init_type_name(&d->group, "", interface_type);
config_item_set_name(&d->group.cg_item, "interface.%s",
names[n_interf]);
interface_groups[n_interf] = &d->group;
}
return 0;
}
EXPORT_SYMBOL(usb_os_desc_prepare_interf_dir);
static int configfs_do_nothing(struct usb_composite_dev *cdev)
{
WARN_ON(1);
return -EINVAL;
}
int composite_dev_prepare(struct usb_composite_driver *composite,
struct usb_composite_dev *dev);
int composite_os_desc_req_prepare(struct usb_composite_dev *cdev,
struct usb_ep *ep0);
static void purge_configs_funcs(struct gadget_info *gi)
{
struct usb_configuration *c;
list_for_each_entry(c, &gi->cdev.configs, list) {
struct usb_function *f, *tmp;
struct config_usb_cfg *cfg;
cfg = container_of(c, struct config_usb_cfg, c);
list_for_each_entry_safe(f, tmp, &c->functions, list) {
list_move_tail(&f->list, &cfg->func_list);
if (f->unbind) {
dev_err(&gi->cdev.gadget->dev, "unbind function"
" '%s'/%p\n", f->name, f);
f->unbind(c, f);
}
}
c->next_interface_id = 0;
c->superspeed = 0;
c->highspeed = 0;
c->fullspeed = 0;
}
}
static int configfs_composite_bind(struct usb_gadget *gadget,
struct usb_gadget_driver *gdriver)
{
struct usb_composite_driver *composite = to_cdriver(gdriver);
struct gadget_info *gi = container_of(composite,
struct gadget_info, composite);
struct usb_composite_dev *cdev = &gi->cdev;
struct usb_configuration *c;
struct usb_string *s;
unsigned i;
int ret;
/* the gi->lock is hold by the caller */
cdev->gadget = gadget;
set_gadget_data(gadget, cdev);
ret = composite_dev_prepare(composite, cdev);
if (ret)
return ret;
/* and now the gadget bind */
ret = -EINVAL;
if (list_empty(&gi->cdev.configs)) {
pr_err("Need at least one configuration in %s.\n",
gi->composite.name);
goto err_comp_cleanup;
}
list_for_each_entry(c, &gi->cdev.configs, list) {
struct config_usb_cfg *cfg;
cfg = container_of(c, struct config_usb_cfg, c);
if (list_empty(&cfg->func_list)) {
pr_err("Config %s/%d of %s needs at least one function.\n",
c->label, c->bConfigurationValue,
gi->composite.name);
goto err_comp_cleanup;
}
}
/* init all strings */
if (!list_empty(&gi->string_list)) {
struct gadget_strings *gs;
i = 0;
list_for_each_entry(gs, &gi->string_list, list) {
gi->gstrings[i] = &gs->stringtab_dev;
gs->stringtab_dev.strings = gs->strings;
gs->strings[USB_GADGET_MANUFACTURER_IDX].s =
gs->manufacturer;
gs->strings[USB_GADGET_PRODUCT_IDX].s = gs->product;
gs->strings[USB_GADGET_SERIAL_IDX].s = gs->serialnumber;
i++;
}
gi->gstrings[i] = NULL;
s = usb_gstrings_attach(&gi->cdev, gi->gstrings,
USB_GADGET_FIRST_AVAIL_IDX);
if (IS_ERR(s)) {
ret = PTR_ERR(s);
goto err_comp_cleanup;
}
gi->cdev.desc.iManufacturer = s[USB_GADGET_MANUFACTURER_IDX].id;
gi->cdev.desc.iProduct = s[USB_GADGET_PRODUCT_IDX].id;
gi->cdev.desc.iSerialNumber = s[USB_GADGET_SERIAL_IDX].id;
}
if (gi->use_os_desc) {
cdev->use_os_string = true;
cdev->b_vendor_code = gi->b_vendor_code;
memcpy(cdev->qw_sign, gi->qw_sign, OS_STRING_QW_SIGN_LEN);
}
/* Go through all configs, attach all functions */
list_for_each_entry(c, &gi->cdev.configs, list) {
struct config_usb_cfg *cfg;
struct usb_function *f;
struct usb_function *tmp;
struct gadget_config_name *cn;
cfg = container_of(c, struct config_usb_cfg, c);
if (!list_empty(&cfg->string_list)) {
i = 0;
list_for_each_entry(cn, &cfg->string_list, list) {
cfg->gstrings[i] = &cn->stringtab_dev;
cn->stringtab_dev.strings = &cn->strings;
cn->strings.s = cn->configuration;
i++;
}
cfg->gstrings[i] = NULL;
s = usb_gstrings_attach(&gi->cdev, cfg->gstrings, 1);
if (IS_ERR(s)) {
ret = PTR_ERR(s);
goto err_comp_cleanup;
}
c->iConfiguration = s[0].id;
}
list_for_each_entry_safe(f, tmp, &cfg->func_list, list) {
list_del(&f->list);
ret = usb_add_function(c, f);
if (ret) {
list_add(&f->list, &cfg->func_list);
goto err_purge_funcs;
}
}
usb_ep_autoconfig_reset(cdev->gadget);
}
if (cdev->use_os_string) {
ret = composite_os_desc_req_prepare(cdev, gadget->ep0);
if (ret)
goto err_purge_funcs;
}
usb_ep_autoconfig_reset(cdev->gadget);
return 0;
err_purge_funcs:
purge_configs_funcs(gi);
err_comp_cleanup:
composite_dev_cleanup(cdev);
return ret;
}
static void configfs_composite_unbind(struct usb_gadget *gadget)
{
struct usb_composite_dev *cdev;
struct gadget_info *gi;
/* the gi->lock is hold by the caller */
cdev = get_gadget_data(gadget);
gi = container_of(cdev, struct gadget_info, cdev);
purge_configs_funcs(gi);
composite_dev_cleanup(cdev);
usb_ep_autoconfig_reset(cdev->gadget);
cdev->gadget = NULL;
set_gadget_data(gadget, NULL);
}
static const struct usb_gadget_driver configfs_driver_template = {
.bind = configfs_composite_bind,
.unbind = configfs_composite_unbind,
.setup = composite_setup,
.reset = composite_disconnect,
.disconnect = composite_disconnect,
.suspend = composite_suspend,
.resume = composite_resume,
.max_speed = USB_SPEED_SUPER,
.driver = {
.owner = THIS_MODULE,
.name = "configfs-gadget",
},
};
static struct config_group *gadgets_make(
struct config_group *group,
const char *name)
{
struct gadget_info *gi;
gi = kzalloc(sizeof(*gi), GFP_KERNEL);
if (!gi)
return ERR_PTR(-ENOMEM);
gi->group.default_groups = gi->default_groups;
gi->group.default_groups[0] = &gi->functions_group;
gi->group.default_groups[1] = &gi->configs_group;
gi->group.default_groups[2] = &gi->strings_group;
gi->group.default_groups[3] = &gi->os_desc_group;
config_group_init_type_name(&gi->functions_group, "functions",
&functions_type);
config_group_init_type_name(&gi->configs_group, "configs",
&config_desc_type);
config_group_init_type_name(&gi->strings_group, "strings",
&gadget_strings_strings_type);
config_group_init_type_name(&gi->os_desc_group, "os_desc",
&os_desc_type);
gi->composite.bind = configfs_do_nothing;
gi->composite.unbind = configfs_do_nothing;
gi->composite.suspend = NULL;
gi->composite.resume = NULL;
gi->composite.max_speed = USB_SPEED_SUPER;
mutex_init(&gi->lock);
INIT_LIST_HEAD(&gi->string_list);
INIT_LIST_HEAD(&gi->available_func);
composite_init_dev(&gi->cdev);
gi->cdev.desc.bLength = USB_DT_DEVICE_SIZE;
gi->cdev.desc.bDescriptorType = USB_DT_DEVICE;
gi->cdev.desc.bcdDevice = cpu_to_le16(get_default_bcdDevice());
gi->composite.gadget_driver = configfs_driver_template;
gi->composite.gadget_driver.function = kstrdup(name, GFP_KERNEL);
gi->composite.name = gi->composite.gadget_driver.function;
if (!gi->composite.gadget_driver.function)
goto err;
#ifdef CONFIG_USB_OTG
gi->otg.bLength = sizeof(struct usb_otg_descriptor);
gi->otg.bDescriptorType = USB_DT_OTG;
gi->otg.bmAttributes = USB_OTG_SRP | USB_OTG_HNP;
#endif
config_group_init_type_name(&gi->group, name,
&gadget_root_type);
return &gi->group;
err:
kfree(gi);
return ERR_PTR(-ENOMEM);
}
static void gadgets_drop(struct config_group *group, struct config_item *item)
{
config_item_put(item);
}
static struct configfs_group_operations gadgets_ops = {
.make_group = &gadgets_make,
.drop_item = &gadgets_drop,
};
static struct config_item_type gadgets_type = {
.ct_group_ops = &gadgets_ops,
.ct_owner = THIS_MODULE,
};
static struct configfs_subsystem gadget_subsys = {
.su_group = {
.cg_item = {
.ci_namebuf = "usb_gadget",
.ci_type = &gadgets_type,
},
},
.su_mutex = __MUTEX_INITIALIZER(gadget_subsys.su_mutex),
};
void unregister_gadget_item(struct config_item *item)
{
struct gadget_info *gi = to_gadget_info(item);
unregister_gadget(gi);
}
EXPORT_SYMBOL_GPL(unregister_gadget_item);
static int __init gadget_cfs_init(void)
{
int ret;
config_group_init(&gadget_subsys.su_group);
ret = configfs_register_subsystem(&gadget_subsys);
return ret;
}
module_init(gadget_cfs_init);
static void __exit gadget_cfs_exit(void)
{
configfs_unregister_subsystem(&gadget_subsys);
}
module_exit(gadget_cfs_exit);