Commit fae76e9a authored by Peter Hurley's avatar Peter Hurley Committed by Greg Kroah-Hartman

tty: Fix hung task on pty hangup

When hanging up one end of a pty pair, there may be waiting
readers/writers on the other end which may not exit, preventing
tty_ldisc_lock_pair() from acquiring the other side's ldisc lock.

Only acquire this side's ldisc lock; although this will no longer
prevent the other side from writing new input, that input will not
be processing until after the ldisc hangup is complete.
Reported-by: default avatarSasha Levin <sasha.levin@oracle.com>
Reviewed-by: default avatarAlan Cox <alan@linux.intel.com>
Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e80a10ee
......@@ -325,6 +325,24 @@ static inline void __tty_ldisc_unlock(struct tty_struct *tty)
return ldsem_up_write(&tty->ldisc_sem);
}
static int __lockfunc
tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout)
{
int ret;
ret = __tty_ldisc_lock(tty, timeout);
if (!ret)
return -EBUSY;
set_bit(TTY_LDISC_HALTED, &tty->flags);
return 0;
}
static void tty_ldisc_unlock(struct tty_struct *tty)
{
clear_bit(TTY_LDISC_HALTED, &tty->flags);
__tty_ldisc_unlock(tty);
}
static int __lockfunc
tty_ldisc_lock_pair_timeout(struct tty_struct *tty, struct tty_struct *tty2,
unsigned long timeout)
......@@ -682,7 +700,7 @@ void tty_ldisc_hangup(struct tty_struct *tty)
*
* Avoid racing set_ldisc or tty_ldisc_release
*/
tty_ldisc_lock_pair(tty, tty->link);
tty_ldisc_lock(tty, MAX_SCHEDULE_TIMEOUT);
if (tty->ldisc) {
......@@ -704,7 +722,7 @@ void tty_ldisc_hangup(struct tty_struct *tty)
WARN_ON(tty_ldisc_open(tty, tty->ldisc));
}
}
tty_ldisc_enable_pair(tty, tty->link);
tty_ldisc_unlock(tty);
if (reset)
tty_reset_termios(tty);
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment