[PATCHv4 4/7] tty: Simplify tty->count math in tty_reopen()

[Dmitry Safonov]

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

Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
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>
---
 drivers/tty/tty_io.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index a947719b4626..7f968ac14bbd 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1268,17 +1268,13 @@ static int tty_reopen(struct tty_struct *tty)
 		return -EBUSY;
 
 	tty_ldisc_lock(tty, MAX_SCHEDULE_TIMEOUT);
+	if (!tty->ldisc)
+		retval = tty_ldisc_reinit(tty, tty->termios.c_line);
+	tty_ldisc_unlock(tty);
 
-	tty->count++;
-	if (tty->ldisc)
-		goto out_unlock;
+	if (retval == 0)
+		tty->count++;
 
-	retval = tty_ldisc_reinit(tty, tty->termios.c_line);
-	if (retval)
-		tty->count--;
-
-out_unlock:
-	tty_ldisc_unlock(tty);
 	return retval;
 }
 
-- 
2.13.6