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Commit df92d056 authored by Jiri Slaby's avatar Jiri Slaby Committed by Greg Kroah-Hartman
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TTY: ldisc, allow waiting for ldisc arbitrarily long 



To fix a nasty bug in ldisc hup vs. reinit we need to wait infinitely
long for ldisc to be gone. So here we add a parameter to
tty_ldisc_wait_idle to allow that.

This is only a preparation for the real fix which is done in the
following patches.

Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
Cc: Dave Young <hidave.darkstar@gmail.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: Dmitriy Matrosov <sgf.dma@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 6edf0c9b

drivers/tty/tty_ldisc.c

+6 −5
Original line number Diff line number Diff line
@@ -547,15 +547,16 @@ static void tty_ldisc_flush_works(struct tty_struct *tty) 
/**

 *	tty_ldisc_wait_idle	-	wait for the ldisc to become idle

 *	@tty: tty to wait for

 *	@timeout: for how long to wait at most

 *

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

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

 */

static int tty_ldisc_wait_idle(struct tty_struct *tty)

static int tty_ldisc_wait_idle(struct tty_struct *tty, long timeout)

{

	int ret;

	long ret;

	ret = wait_event_timeout(tty_ldisc_idle,

			atomic_read(&tty->ldisc->users) == 1, 5 * HZ);

			atomic_read(&tty->ldisc->users) == 1, timeout);

	if (ret < 0)

		return ret;

	return ret > 0 ? 0 : -EBUSY;
@@ -665,7 +666,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc) 


	tty_ldisc_flush_works(tty);



	retval = tty_ldisc_wait_idle(tty);

	retval = tty_ldisc_wait_idle(tty, 5 * HZ);



	tty_lock();

	mutex_lock(&tty->ldisc_mutex);
@@ -762,7 +763,7 @@ static int tty_ldisc_reinit(struct tty_struct *tty, int ldisc) 
	if (IS_ERR(ld))

		return -1;



	WARN_ON_ONCE(tty_ldisc_wait_idle(tty));

	WARN_ON_ONCE(tty_ldisc_wait_idle(tty, 5 * HZ));



	tty_ldisc_close(tty, tty->ldisc);

	tty_ldisc_put(tty->ldisc);