diff options
| author | Peter Hurley <peter@hurleysoftware.com> | 2014-11-05 20:13:07 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-11-06 05:50:43 +0300 |
| commit | fae76e9adfa450f4c2dd5773265eb3c811a9c484 (patch) | |
| tree | 88f6086470fe19b2299568b24e4b27d8e3c608f7 | |
| parent | e80a10ee4de8f654cf34170da00f989470331da8 (diff) | |
| download | linux-fae76e9adfa450f4c2dd5773265eb3c811a9c484.tar.xz | |
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: Sasha Levin <sasha.levin@oracle.com>
Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/tty/tty_ldisc.c | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c index 5bdc241628ac..1dbe27824220 100644 --- a/drivers/tty/tty_ldisc.c +++ b/drivers/tty/tty_ldisc.c @@ -326,6 +326,24 @@ static inline void __tty_ldisc_unlock(struct tty_struct *tty) } 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); |