linux-kernel - [PATCHv3 5/6] tty: Simplify tty->count math in tty

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Date:   Tue, 11 Sep 2018 02:48:20 +0100
From:   Dmitry Safonov <dima@...sta.com>
To:     linux-kernel@...r.kernel.org
Cc:     Dmitry Safonov <0x7f454c46@...il.com>,
        Dmitry Safonov <dima@...sta.com>,
        Daniel Axtens <dja@...ens.net>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Michael Neuling <mikey@...ling.org>,
        Mikulas Patocka <mpatocka@...hat.com>,
        Nathan March <nathan@...net>,
        Pasi Kärkkäinen <pasik@....fi>,
        Peter Hurley <peter@...leysoftware.com>,
        "Rong, Chen" <rong.a.chen@...el.com>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Tan Xiaojun <tanxiaojun@...wei.com>,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        Jiri Slaby <jslaby@...e.com>, Jiri Slaby <jslaby@...e.cz>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: [PATCHv3 5/6] tty: Simplify tty->count math in tty_reopen()

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@...uxfoundation.org>
Cc: Jiri Slaby <jslaby@...e.com>
Link: lkml.kernel.org/r/<20180829022353.23568-2-dima@...sta.com>
Suggested-by: Jiri Slaby <jslaby@...e.com>
Reviewed-by: Jiri Slaby <jslaby@...e.cz>
Signed-off-by: Dmitry Safonov <dima@...sta.com>
---
 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