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Commit 7896f30d authored by Peter Hurley's avatar Peter Hurley Committed by Greg Kroah-Hartman
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tty: Refactor tty_ldisc_reinit() for reuse 



At tty hangup, the line discipline instance is reinitialized by
closing the current ldisc instance and opening a new instance.
This operation is complicated by error recovery: if the attempt
to reinit the current line discipline fails, the line discipline
is reset to N_TTY (which should not but can fail).

Re-purpose tty_ldisc_reinit() to return a valid, open line discipline
instance, or otherwise, an error.

Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c12da96f

drivers/tty/tty_ldisc.c

+31 −22
Original line number Diff line number Diff line
@@ -641,26 +641,41 @@ static void tty_reset_termios(struct tty_struct *tty) 
 *	@tty: tty to reinit

 *	@disc: line discipline to reinitialize

 *

 *	Switch the tty to a line discipline and leave the ldisc

 *	state closed

 *	Completely reinitialize the line discipline state, by closing the

 *	current instance and opening a new instance. If an error occurs opening

 *	the new non-N_TTY instance, the instance is dropped and tty->ldisc reset

 *	to NULL. The caller can then retry with N_TTY instead.

 *

 *	Returns 0 if successful, otherwise error code < 0

 */



static int tty_ldisc_reinit(struct tty_struct *tty, int disc)

{

	struct tty_ldisc *ld = tty_ldisc_get(tty, disc);

	struct tty_ldisc *ld;

	int retval;



	if (IS_ERR(ld))

		return -1;

	ld = tty_ldisc_get(tty, disc);

	if (IS_ERR(ld)) {

		BUG_ON(disc == N_TTY);

		return PTR_ERR(ld);

	}



	if (tty->ldisc) {

		tty_ldisc_close(tty, tty->ldisc);

		tty_ldisc_put(tty->ldisc);

	/*

	 *	Switch the line discipline back

	 */

	}



	/* switch the line discipline */

	tty->ldisc = ld;

	tty_set_termios_ldisc(tty, disc);



	return 0;

	retval = tty_ldisc_open(tty, tty->ldisc);

	if (retval) {

		if (!WARN_ON(disc == N_TTY)) {

			tty_ldisc_put(tty->ldisc);

			tty->ldisc = NULL;

		}

	}

	return retval;

}



/**
@@ -716,19 +731,13 @@ void tty_ldisc_hangup(struct tty_struct *tty) 
		   reopen a new ldisc. We could defer the reopen to the next

		   open but it means auditing a lot of other paths so this is

		   a FIXME */

		if (reset == 0) {

		if (reset == 0)

			err = tty_ldisc_reinit(tty, tty->termios.c_line);



			if (!tty_ldisc_reinit(tty, tty->termios.c_line))

				err = tty_ldisc_open(tty, tty->ldisc);

			else

				err = 1;

		}

		/* If the re-open fails or we reset then go to N_TTY. The

		   N_TTY open cannot fail */

		if (reset || err) {

			BUG_ON(tty_ldisc_reinit(tty, N_TTY));

			WARN_ON(tty_ldisc_open(tty, tty->ldisc));

		}

		if (reset || err < 0)

			tty_ldisc_reinit(tty, N_TTY);

	}

	tty_ldisc_unlock(tty);

	if (reset)