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Commit e8b70e7d authored by Alan Cox's avatar Alan Cox Committed by Linus Torvalds
Browse files

tty: Extract various bits of ldisc code 



Before trying to tackle the ldisc bugs the code needs to be a good deal
more readable, so do the simple extractions of routines first.

Signed-off-by: default avatarAlan Cox <alan@linux.intel.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 5f0878ac

drivers/char/tty_io.c

+19 −5
Original line number Diff line number Diff line
@@ -2481,6 +2481,24 @@ static int tty_tiocmset(struct tty_struct *tty, struct file *file, unsigned int 
	return tty->ops->tiocmset(tty, file, set, clear);

}



struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)

{

	if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&

	    tty->driver->subtype == PTY_TYPE_MASTER)

		tty = tty->link;

	return tty;

}

EXPORT_SYMBOL(tty_pair_get_tty);



struct tty_struct *tty_pair_get_pty(struct tty_struct *tty)

{

	if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&

	    tty->driver->subtype == PTY_TYPE_MASTER)

	    return tty;

	return tty->link;

}

EXPORT_SYMBOL(tty_pair_get_pty);



/*

 * Split this up, as gcc can choke on it otherwise..

 */
@@ -2496,11 +2514,7 @@ long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 
	if (tty_paranoia_check(tty, inode, "tty_ioctl"))

		return -EINVAL;



	real_tty = tty;

	if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&

	    tty->driver->subtype == PTY_TYPE_MASTER)

		real_tty = tty->link;



	real_tty = tty_pair_get_tty(tty);



	/*

	 * Factor out some common prep work

drivers/char/tty_ldisc.c

+66 −31
Original line number Diff line number Diff line
@@ -443,6 +443,50 @@ static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old) 
	}

}



/**

 *	tty_ldisc_halt		-	shutdown the line discipline

 *	@tty: tty device

 *

 *	Shut down the line discipline and work queue for this tty device.

 *	The TTY_LDISC flag being cleared ensures no further references can

 *	be obtained while the delayed work queue halt ensures that no more

 *	data is fed to the ldisc.

 *

 *	In order to wait for any existing references to complete see 

 *	tty_ldisc_wait_idle.

 */



static void tty_ldisc_halt(struct tty_struct *tty)

{

	clear_bit(TTY_LDISC, &tty->flags);

	cancel_delayed_work(&tty->buf.work);

	/*

	 * Wait for ->hangup_work and ->buf.work handlers to terminate

	 */

	flush_scheduled_work();

}



/**

 *	tty_ldisc_wait_idle	-	wait for the ldisc to become idle

 *	@tty: tty to wait for

 *

 *	Wait for the line discipline to become idle. The discipline must

 *	have been halted for this to guarantee it remains idle.

 *

 */



static void tty_ldisc_wait_idle(struct tty_struct *tty)

{

	unsigned long flags;

	spin_lock_irqsave(&tty_ldisc_lock, flags);

	while (tty->ldisc.refcount) {

		spin_unlock_irqrestore(&tty_ldisc_lock, flags);

		wait_event(tty_ldisc_wait, tty->ldisc.refcount == 0);

		spin_lock_irqsave(&tty_ldisc_lock, flags);

	}

	spin_unlock_irqrestore(&tty_ldisc_lock, flags);

}



/**

 *	tty_set_ldisc		-	set line discipline

 *	@tty: the terminal to set
@@ -636,6 +680,21 @@ int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty) 
	return 0;

}



static void tty_ldisc_reinit(struct tty_struct *tty)

{

	struct tty_ldisc ld;



	if (tty->ldisc.ops->close)

		(tty->ldisc.ops->close)(tty);

	tty_ldisc_put(tty->ldisc.ops);

	/*

	 *	Switch the line discipline back

	 */

	WARN_ON(tty_ldisc_get(N_TTY, &ld));

	tty_ldisc_assign(tty, &ld);

	tty_set_termios_ldisc(tty, N_TTY);

}



/**

 *	tty_ldisc_release		-	release line discipline

 *	@tty: tty being shut down
@@ -647,58 +706,34 @@ int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty) 


void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty)

{

	unsigned long flags;

	struct tty_ldisc ld;



	/*

	 * Prevent flush_to_ldisc() from rescheduling the work for later.  Then

	 * kill any delayed work. As this is the final close it does not

	 * race with the set_ldisc code path.

	 */

	clear_bit(TTY_LDISC, &tty->flags);

	cancel_delayed_work(&tty->buf.work);



	/*

	 * Wait for ->hangup_work and ->buf.work handlers to terminate

	 */



	flush_scheduled_work();

	tty_ldisc_halt(tty);



	/*

	 * Wait for any short term users (we know they are just driver

	 * side waiters as the file is closing so user count on the file

	 * side is zero.

	 */

	spin_lock_irqsave(&tty_ldisc_lock, flags);

	while (tty->ldisc.refcount) {

		spin_unlock_irqrestore(&tty_ldisc_lock, flags);

		wait_event(tty_ldisc_wait, tty->ldisc.refcount == 0);

		spin_lock_irqsave(&tty_ldisc_lock, flags);

	}

	spin_unlock_irqrestore(&tty_ldisc_lock, flags);



	tty_ldisc_wait_idle(tty);



	/*

	 * Shutdown the current line discipline, and reset it to N_TTY.

	 *

	 * FIXME: this MUST get fixed for the new reflocking

	 */

	if (tty->ldisc.ops->close)

		(tty->ldisc.ops->close)(tty);

	tty_ldisc_put(tty->ldisc.ops);



	/*

	 *	Switch the line discipline back

	 */

	WARN_ON(tty_ldisc_get(N_TTY, &ld));

	tty_ldisc_assign(tty, &ld);

	tty_set_termios_ldisc(tty, N_TTY);

	tty_ldisc_reinit(tty);

	if (o_tty) {

		/* FIXME: could o_tty be in setldisc here ? */

		clear_bit(TTY_LDISC, &o_tty->flags);

		if (o_tty->ldisc.ops->close)

			(o_tty->ldisc.ops->close)(o_tty);

		tty_ldisc_put(o_tty->ldisc.ops);

		WARN_ON(tty_ldisc_get(N_TTY, &ld));

		tty_ldisc_assign(o_tty, &ld);

		tty_set_termios_ldisc(o_tty, N_TTY);

		tty_ldisc_reinit(o_tty);

	}

}

include/linux/tty.h

+3 −0
Original line number Diff line number Diff line
@@ -428,6 +428,9 @@ extern struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx, 
extern void tty_release_dev(struct file *filp);

extern int tty_init_termios(struct tty_struct *tty);



extern struct tty_struct *tty_pair_get_tty(struct tty_struct *tty);

extern struct tty_struct *tty_pair_get_pty(struct tty_struct *tty);



extern struct mutex tty_mutex;



extern void tty_write_unlock(struct tty_struct *tty);