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Commit 23499705 authored by Sukadev Bhattiprolu's avatar Sukadev Bhattiprolu Committed by Linus Torvalds
Browse files

tty: Move parts of tty_init_dev into new functions 



Move the 'find-tty' and 'fast-track-open' parts of init_dev() to
separate functions.

Signed-off-by: default avatarSukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: default avatarAlan Cox <alan@redhat.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d81ed103

drivers/char/tty_io.c

+87 −52
Original line number Original line Diff line number Diff line
@@ -1204,6 +1204,80 @@ static void tty_line_name(struct tty_driver *driver, int index, char *p) 
	sprintf(p, "%s%d", driver->name, index + driver->name_base);

	sprintf(p, "%s%d", driver->name, index + driver->name_base);

}

}





/*

 * 	find_tty() - find an existing tty, if any

 * 	@driver: the driver for the tty

 * 	@idx:	 the minor number

 *

 * 	Return the tty, if found or ERR_PTR() otherwise.

 *

 * 	Locking: tty_mutex must be held. If tty is found, the mutex must

 * 		 be held until the 'fast-open' is also done.

 */

struct tty_struct *find_tty(struct tty_driver *driver, int idx)

{

	struct tty_struct *tty;



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

	if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {

		tty = devpts_get_tty(idx);

		/*

		 * If we don't have a tty here on a slave open, it's because

		 * the master already started the close process and there's

		 * no relation between devpts file and tty anymore.

		 */

		if (!tty && driver->subtype == PTY_TYPE_SLAVE)

			return ERR_PTR(-EIO);



		/*

		 * tty is safe on because we are called with tty_mutex held

		 * and release_dev() won't change tty->count or tty->flags

		 * without grabbing tty_mutex.

		 */

		if (tty && driver->subtype == PTY_TYPE_MASTER)

			tty = tty->link;

	} else

		tty = driver->ttys[idx];

	return tty;

}



/*

 * 	fast_tty_open()	- fast re-open of an open tty

 * 	@tty	- the tty to open

 *

 * 	Return 0 on success, -errno on error.

 *

 * 	Locking: tty_mutex must be held from the time the tty was found

 * 		 till this open completes.

 */

static int fast_tty_open(struct tty_struct *tty)

{

	struct tty_driver *driver = tty->driver;



	if (test_bit(TTY_CLOSING, &tty->flags))

		return -EIO;



	if (driver->type == TTY_DRIVER_TYPE_PTY &&

	    driver->subtype == PTY_TYPE_MASTER) {

		/*

		 * special case for PTY masters: only one open permitted,

		 * and the slave side open count is incremented as well.

		 */

		if (tty->count)

			return -EIO;



		tty->link->count++;

	}

	tty->count++;

	tty->driver = driver; /* N.B. why do this every time?? */



	/* FIXME */

	if (!test_bit(TTY_LDISC, &tty->flags))

		printk(KERN_ERR "fast_tty_open: no ldisc\n");



	return 0;

}



/**

/**

 *	tty_init_dev		-	initialise a tty device

 *	tty_init_dev		-	initialise a tty device

 *	@driver: tty driver we are opening a device on

 *	@driver: tty driver we are opening a device on
@@ -1238,29 +1312,21 @@ int tty_init_dev(struct tty_driver *driver, int idx, 
	int retval = 0;

	int retval = 0;





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

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

	if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {

	tty = find_tty(driver, idx);

		tty = devpts_get_tty(idx);

	if (IS_ERR(tty)) {

		/*

		retval = PTR_ERR(tty);

		 * If we don't have a tty here on a slave open, it's because

		 * the master already started the close process and there's

		 * no relation between devpts file and tty anymore.

		 */

		if (!tty && driver->subtype == PTY_TYPE_SLAVE) {

			retval = -EIO;

		goto end_init;

		goto end_init;

	}

	}

		/*



		 * It's safe from now on because tty_init_dev() is called with

	if (tty) {

		 * tty_mutex held and tty_release_dev() won't change tty->count

		retval = fast_tty_open(tty);

		 * or tty->flags without having to grab tty_mutex

		if (retval)

		 */

			return retval;

		if (tty && driver->subtype == PTY_TYPE_MASTER)

		*ret_tty = tty;

			tty = tty->link;

		return 0;

	} else {

		tty = driver->ttys[idx];

	}

	}

	if (tty) goto fast_track;





	/* Check if pty master is being opened multiple times */

	if (driver->subtype == PTY_TYPE_MASTER &&

	if (driver->subtype == PTY_TYPE_MASTER &&

		(driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok) {

		(driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok) {

		retval = -EIO;

		retval = -EIO;
@@ -1400,37 +1466,6 @@ int tty_init_dev(struct tty_driver *driver, int idx, 




	if (retval)

	if (retval)

		goto release_mem_out;

		goto release_mem_out;

	goto success;



	/*

	 * This fast open can be used if the tty is already open.

	 * No memory is allocated, and the only failures are from

	 * attempting to open a closing tty or attempting multiple

	 * opens on a pty master.

	 */

fast_track:

	if (test_bit(TTY_CLOSING, &tty->flags)) {

		retval = -EIO;

		goto end_init;

	}

	if (driver->type == TTY_DRIVER_TYPE_PTY &&

	    driver->subtype == PTY_TYPE_MASTER) {

		/*

		 * special case for PTY masters: only one open permitted,

		 * and the slave side open count is incremented as well.

		 */

		if (tty->count) {

			retval = -EIO;

			goto end_init;

		}

		tty->link->count++;

	}

	tty->count++;

	tty->driver = driver; /* N.B. why do this every time?? */



	/* FIXME */

	if (!test_bit(TTY_LDISC, &tty->flags))

		printk(KERN_ERR "tty_init_dev but no ldisc\n");

success:

success:

	*ret_tty = tty;

	*ret_tty = tty;