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Commit 43104f1d authored by Greg Kroah-Hartman's avatar Greg Kroah-Hartman
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[PATCH] USB: only make /sys/class/usb show up when there is something in it 



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: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent bd009496

drivers/usb/core/file.c

+54 −16
Original line number Diff line number Diff line
@@ -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;



int usb_major_init(void)

static int init_usb_class(void)

{

	int error;

	int result = 0;



	error = register_chrdev(USB_MAJOR, "usb", &usb_fops);

	if (error) {

		err("unable to get major %d for usb devices", USB_MAJOR);

		goto out;

	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;

	}



	usb_class = class_create(THIS_MODULE, "usb");

	if (IS_ERR(usb_class)) {

		error = PTR_ERR(usb_class);

	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");

		unregister_chrdev(USB_MAJOR, "usb");

		goto out;

		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);

}



out:

int usb_major_init(void)

{

	int error;



	error = register_chrdev(USB_MAJOR, "usb", &usb_fops);

	if (error)

		err("unable to get major %d for usb devices", USB_MAJOR);



	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);