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[PATCH] USB: only make /sys/class/usb show up when there is something in it

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Now /sys/class/usb is dynamically created when we have something to put
in it, and removed when all devices go away.

Just trying to cut down on the clutter in sysfs...

Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Greg Kroah-Hartman 2006-06-20 15:14:07 -07:00
parent bd00949647
commit 43104f1da8
1 changed files with 54 additions and 16 deletions
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70
drivers/usb/core/file.c
View file

@ -61,33 +61,66 @@ static struct file_operations usb_fops = {
.open = usb_open,
};
static struct class *usb_class;
static struct usb_class {
struct kref kref;
struct class *class;
} *usb_class;
static int init_usb_class(void)
{
int result = 0;
if (usb_class != NULL) {
kref_get(&usb_class->kref);
goto exit;
}
usb_class = kmalloc(sizeof(*usb_class), GFP_KERNEL);
if (!usb_class) {
result = -ENOMEM;
goto exit;
}
kref_init(&usb_class->kref);
usb_class->class = class_create(THIS_MODULE, "usb");
if (IS_ERR(usb_class->class)) {
result = IS_ERR(usb_class->class);
err("class_create failed for usb devices");
kfree(usb_class);
usb_class = NULL;
}
exit:
return result;
}
static void release_usb_class(struct kref *kref)
{
/* Ok, we cheat as we know we only have one usb_class */
class_destroy(usb_class->class);
kfree(usb_class);
usb_class = NULL;
}
static void destroy_usb_class(void)
{
if (usb_class)
kref_put(&usb_class->kref, release_usb_class);
}
int usb_major_init(void)
{
int error;
error = register_chrdev(USB_MAJOR, "usb", &usb_fops);
if (error) {
if (error)
err("unable to get major %d for usb devices", USB_MAJOR);
goto out;
}
usb_class = class_create(THIS_MODULE, "usb");
if (IS_ERR(usb_class)) {
error = PTR_ERR(usb_class);
err("class_create failed for usb devices");
unregister_chrdev(USB_MAJOR, "usb");
goto out;
}
out:
return error;
}
void usb_major_cleanup(void)
{
class_destroy(usb_class);
unregister_chrdev(USB_MAJOR, "usb");
}
@ -146,6 +179,10 @@ int usb_register_dev(struct usb_interface *intf,
}
spin_unlock (&minor_lock);
if (retval)
goto exit;
retval = init_usb_class();
if (retval)
goto exit;
@ -158,7 +195,7 @@ int usb_register_dev(struct usb_interface *intf,
++temp;
else
temp = name;
intf->usb_dev = device_create(usb_class, &intf->dev,
intf->usb_dev = device_create(usb_class->class, &intf->dev,
MKDEV(USB_MAJOR, minor), "%s", temp);
if (IS_ERR(intf->usb_dev)) {
spin_lock (&minor_lock);
@ -205,9 +242,10 @@ void usb_deregister_dev(struct usb_interface *intf,
spin_unlock (&minor_lock);
snprintf(name, BUS_ID_SIZE, class_driver->name, intf->minor - minor_base);
device_destroy(usb_class, MKDEV(USB_MAJOR, intf->minor));
device_destroy(usb_class->class, MKDEV(USB_MAJOR, intf->minor));
intf->usb_dev = NULL;
intf->minor = -1;
destroy_usb_class();
}
EXPORT_SYMBOL(usb_deregister_dev);