[PATCH 4.14 03/59] tty: Simplify tty->count math in tty_reopen()

From: Greg Kroah-Hartman
Date: Mon Jan 21 2019 - 08:51:40 EST


4.14-stable review patch. If anyone has any objections, please let me know.

------------------

From: Dmitry Safonov <dima@xxxxxxxxxx>

commit cf62a1a13749db0d32b5cdd800ea91a4087319de upstream.

As notted by Jiri, tty_ldisc_reinit() shouldn't rely on tty counter.
Simplify math by increasing the counter after reinit success.

Cc: Jiri Slaby <jslaby@xxxxxxxx>
Link: lkml.kernel.org/r/<20180829022353.23568-2-dima@xxxxxxxxxx>
Suggested-by: Jiri Slaby <jslaby@xxxxxxxx>
Reviewed-by: Jiri Slaby <jslaby@xxxxxxx>
Tested-by: Mark Rutland <mark.rutland@xxxxxxx>
Signed-off-by: Dmitry Safonov <dima@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/tty/tty_io.c | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)

--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1270,16 +1270,13 @@ static int tty_reopen(struct tty_struct
if (retval)
return retval;

- tty->count++;
- if (tty->ldisc)
- goto out_unlock;
+ if (!tty->ldisc)
+ retval = tty_ldisc_reinit(tty, tty->termios.c_line);
+ tty_ldisc_unlock(tty);

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

-out_unlock:
- tty_ldisc_unlock(tty);
return retval;
}