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Commit 7e73eca6 authored by Jiri Slaby's avatar Jiri Slaby Committed by Greg Kroah-Hartman
Browse files

TTY: move cdev_add to tty_register_device 



We need the /dev/ node not to be available before we call
tty_register_device. Otherwise we might race with open and
tty_struct->port might not be available at that time.

This is not an issue now, but would be a problem after "TTY: use
tty_port_register_device" is applied.

Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
Acked-by: default avatarAlan Cox <alan@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0019b408

drivers/tty/tty_io.c

+41 −7
Original line number Original line Diff line number Diff line
@@ -3006,6 +3006,15 @@ EXPORT_SYMBOL_GPL(tty_put_char); 




struct class *tty_class;

struct class *tty_class;





static int tty_cdev_add(struct tty_driver *driver, dev_t dev,

		unsigned int index, unsigned int count)

{

	/* init here, since reused cdevs cause crashes */

	cdev_init(&driver->cdevs[index], &tty_fops);

	driver->cdevs[index].owner = driver->owner;

	return cdev_add(&driver->cdevs[index], dev, count);

}



/**

/**

 *	tty_register_device - register a tty device

 *	tty_register_device - register a tty device

 *	@driver: the tty driver that describes the tty device

 *	@driver: the tty driver that describes the tty device
@@ -3028,8 +3037,10 @@ struct class *tty_class; 
struct device *tty_register_device(struct tty_driver *driver, unsigned index,

struct device *tty_register_device(struct tty_driver *driver, unsigned index,

				   struct device *device)

				   struct device *device)

{

{

	struct device *ret;

	char name[64];

	char name[64];

	dev_t dev = MKDEV(driver->major, driver->minor_start) + index;

	dev_t dev = MKDEV(driver->major, driver->minor_start) + index;

	bool cdev = false;





	if (index >= driver->num) {

	if (index >= driver->num) {

		printk(KERN_ERR "Attempt to register invalid tty line number "

		printk(KERN_ERR "Attempt to register invalid tty line number "
@@ -3042,7 +3053,18 @@ struct device *tty_register_device(struct tty_driver *driver, unsigned index, 
	else

	else

		tty_line_name(driver, index, name);

		tty_line_name(driver, index, name);





	return device_create(tty_class, device, dev, NULL, name);

	if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {

		int error = tty_cdev_add(driver, dev, index, 1);

		if (error)

			return ERR_PTR(error);

		cdev = true;

	}



	ret = device_create(tty_class, device, dev, NULL, name);

	if (IS_ERR(ret) && cdev)

		cdev_del(&driver->cdevs[index]);



	return ret;

}

}

EXPORT_SYMBOL(tty_register_device);

EXPORT_SYMBOL(tty_register_device);
@@ -3061,6 +3083,8 @@ void tty_unregister_device(struct tty_driver *driver, unsigned index) 
{

{

	device_destroy(tty_class,

	device_destroy(tty_class,

		MKDEV(driver->major, driver->minor_start) + index);

		MKDEV(driver->major, driver->minor_start) + index);

	if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC))

		cdev_del(&driver->cdevs[index]);

}

}

EXPORT_SYMBOL(tty_unregister_device);

EXPORT_SYMBOL(tty_unregister_device);
@@ -3077,6 +3101,7 @@ struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner, 
		unsigned long flags)

		unsigned long flags)

{

{

	struct tty_driver *driver;

	struct tty_driver *driver;

	unsigned int cdevs = 1;

	int err;

	int err;





	if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))

	if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))
@@ -3110,6 +3135,13 @@ struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner, 
			err = -ENOMEM;

			err = -ENOMEM;

			goto err_free_all;

			goto err_free_all;

		}

		}

		cdevs = lines;

	}



	driver->cdevs = kcalloc(cdevs, sizeof(*driver->cdevs), GFP_KERNEL);

	if (!driver->cdevs) {

		err = -ENOMEM;

		goto err_free_all;

	}

	}





	return driver;

	return driver;
@@ -3144,8 +3176,10 @@ static void destruct_tty_driver(struct kref *kref) 
				tty_unregister_device(driver, i);

				tty_unregister_device(driver, i);

		}

		}

		proc_tty_unregister_driver(driver);

		proc_tty_unregister_driver(driver);

		cdev_del(&driver->cdev);

		if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)

			cdev_del(&driver->cdevs[0]);

	}

	}

	kfree(driver->cdevs);

	kfree(driver->ports);

	kfree(driver->ports);

	kfree(driver->termios);

	kfree(driver->termios);

	kfree(driver->ttys);

	kfree(driver->ttys);
@@ -3195,11 +3229,11 @@ int tty_register_driver(struct tty_driver *driver) 
	if (error < 0)

	if (error < 0)

		goto err;

		goto err;





	cdev_init(&driver->cdev, &tty_fops);

	if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) {

	driver->cdev.owner = driver->owner;

		error = tty_cdev_add(driver, dev, 0, driver->num);

	error = cdev_add(&driver->cdev, dev, driver->num);

		if (error)

		if (error)

			goto err_unreg_char;

			goto err_unreg_char;

	}





	mutex_lock(&tty_mutex);

	mutex_lock(&tty_mutex);

	list_add(&driver->tty_drivers, &tty_drivers);

	list_add(&driver->tty_drivers, &tty_drivers);

include/linux/tty_driver.h

+1 −1
Original line number Original line Diff line number Diff line
@@ -289,7 +289,7 @@ struct tty_operations { 
struct tty_driver {

struct tty_driver {

	int	magic;		/* magic number for this structure */

	int	magic;		/* magic number for this structure */

	struct kref kref;	/* Reference management */

	struct kref kref;	/* Reference management */

	struct cdev cdev;

	struct cdev *cdevs;

	struct module	*owner;

	struct module	*owner;

	const char	*driver_name;

	const char	*driver_name;

	const char	*name;

	const char	*name;