[PATCHv2 1/4] tty: Drop tty->count on tty_reopen() failure

Dmitry Safonov
2018-09-03T16:53:05Z

In case of tty_ldisc_reinit() failure, tty->count should be decremented
back, otherwise we will never release_tty().
Tetsuo reported that it fixes noisy warnings on tty release like:
pts pts4033: tty_release: tty->count(10529) != (#fd's(7) + #kopen's(0))

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: stable@vger.kernel.org # v4.6+
Fixes: commit 892d1fa7eaae ("tty: Destroy ldisc instance on hangup")
Tested-by: Jiri Slaby <jslaby@suse.com>
Tested-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
drivers/tty/tty_io.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 32bc3e3fe4d3..5e5da9acaf0a 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1255,6 +1255,7 @@ static void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *
static int tty_reopen(struct tty_struct *tty)
{
struct tty_driver *driver = tty->driver;
+ int retval;

if (driver->type == TTY_DRIVER_TYPE_PTY &&
driver->subtype == PTY_TYPE_MASTER)
@@ -1268,10 +1269,14 @@ static int tty_reopen(struct tty_struct *tty)

tty->count++;

- if (!tty->ldisc)
- return tty_ldisc_reinit(tty, tty->termios.c_line);
+ if (tty->ldisc)
+ return 0;

- return 0;
+ retval = tty_ldisc_reinit(tty, tty->termios.c_line);
+ if (retval)
+ tty->count--;
+
+ return retval;
}

/**
--
2.13.6