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Commit 5b5e7040 authored by Jiri Slaby's avatar Jiri Slaby Committed by Greg Kroah-Hartman
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TTY: extract driver lookup from tty_open 



The error handling in tty_open became unbearable. There were many
errors fixed recently. Extract the tty driver lookup from tty_open to
a separate function. This reduces the fail paths significantly and
makes tty_open more readable.

In the next patch we will move the fail path handling to the end of
the function.

Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent b82154ac

drivers/tty/tty_io.c

+55 −38
Original line number Diff line number Diff line
@@ -1823,6 +1823,53 @@ static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp) 
	return tty;

}



/**

 *	tty_lookup_driver - lookup a tty driver for a given device file

 *	@device: device number

 *	@filp: file pointer to tty

 *	@noctty: set if the device should not become a controlling tty

 *	@index: index for the device in the @return driver

 *	@return: driver for this inode (with increased refcount)

 *

 * 	If @return is not erroneous, the caller is responsible to decrement the

 * 	refcount by tty_driver_kref_put.

 *

 *	Locking: tty_mutex protects get_tty_driver

 */

static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,

		int *noctty, int *index)

{

	struct tty_driver *driver;



#ifdef CONFIG_VT

	if (device == MKDEV(TTY_MAJOR, 0)) {

		extern struct tty_driver *console_driver;

		driver = tty_driver_kref_get(console_driver);

		*index = fg_console;

		*noctty = 1;

		return driver;

	}

#endif

	if (device == MKDEV(TTYAUX_MAJOR, 1)) {

		struct tty_driver *console_driver = console_device(index);

		if (console_driver) {

			driver = tty_driver_kref_get(console_driver);

			if (driver) {

				/* Don't let /dev/console block */

				filp->f_flags |= O_NONBLOCK;

				*noctty = 1;

				return driver;

			}

		}

		return ERR_PTR(-ENODEV);

	}



	driver = get_tty_driver(device, index);

	if (!driver)

		return ERR_PTR(-ENODEV);

	return driver;

}



/**

 *	tty_open		-	open a tty device

 *	@inode: inode of device file
@@ -1839,7 +1886,7 @@ static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp) 
 *	The termios state of a pty is reset on first open so that

 *	settings don't persist across reuse.

 *

 *	Locking: tty_mutex protects tty, get_tty_driver and tty_init_dev work.

 *	Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev.

 *		 tty->count should protect the rest.

 *		 ->siglock protects ->signal/->sighand

 */
@@ -1873,47 +1920,17 @@ static int tty_open(struct inode *inode, struct file *filp) 
		mutex_unlock(&tty_mutex);

		tty_free_file(filp);

		return PTR_ERR(tty);

	} else if (tty)

		goto got_driver;



#ifdef CONFIG_VT

	if (device == MKDEV(TTY_MAJOR, 0)) {

		extern struct tty_driver *console_driver;

		driver = tty_driver_kref_get(console_driver);

		index = fg_console;

		noctty = 1;

		goto got_driver;

	}

#endif

	if (device == MKDEV(TTYAUX_MAJOR, 1)) {

		struct tty_driver *console_driver = console_device(&index);

		if (console_driver) {

			driver = tty_driver_kref_get(console_driver);

			if (driver) {

				/* Don't let /dev/console block */

				filp->f_flags |= O_NONBLOCK;

				noctty = 1;

				goto got_driver;

			}

		}

	} else if (!tty) {

		driver = tty_lookup_driver(device, filp, &noctty, &index);

		if (IS_ERR(driver)) {

			tty_unlock();

			mutex_unlock(&tty_mutex);

			tty_free_file(filp);

		return -ENODEV;

			return PTR_ERR(driver);

		}



	driver = get_tty_driver(device, &index);

	if (!driver) {

		tty_unlock();

		mutex_unlock(&tty_mutex);

		tty_free_file(filp);

		return -ENODEV;

	}

got_driver:

	if (!tty) {

		/* check whether we're reopening an existing tty */

		tty = tty_driver_lookup_tty(driver, inode, index);



		if (IS_ERR(tty)) {

			tty_unlock();

			mutex_unlock(&tty_mutex);