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From:   Dmitry Safonov <dima@arista.com>
To:     linux-kernel@vger.kernel.org
Cc:     Dmitry Safonov <0x7f454c46@gmail.com>,
        Dmitry Safonov <dima@arista.com>,
        Daniel Axtens <dja@axtens.net>,
        Dmitry Vyukov <dvyukov@google.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Michael Neuling <mikey@neuling.org>,
        Mikulas Patocka <mpatocka@redhat.com>,
        Nathan March <nathan@gt.net>,
        =?UTF-8?q?Pasi=20K=C3=A4rkk=C3=A4inen?= <pasik@iki.fi>,
        Peter Hurley <peter@hurleysoftware.com>,
        Peter Zijlstra <peterz@infradead.org>,
        "Rong, Chen" <rong.a.chen@intel.com>,
        Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
        Tan Xiaojun <tanxiaojun@huawei.com>,
        Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
        Jiri Slaby <jslaby@suse.com>, Jiri Slaby <jslaby@suse.cz>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: [PATCHv6 4/7] tty: Simplify tty->count math in tty_reopen()
Date:   Thu,  1 Nov 2018 00:24:49 +0000
Message-Id: <20181101002452.5483-5-dima@arista.com>
In-Reply-To: <20181101002452.5483-1-dima@arista.com>
References: <20181101002452.5483-1-dima@arista.com>
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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@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Link: lkml.kernel.org/r/<20180829022353.23568-2-dima@arista.com>
Suggested-by: Jiri Slaby <jslaby@suse.com>
Reviewed-by: Jiri Slaby <jslaby@suse.cz>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 drivers/tty/tty_io.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index f73d8fa7f02b..57d06eda5b2f 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1272,16 +1272,13 @@ static int tty_reopen(struct tty_struct *tty)
 	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;
 }
 
-- 
2.19.1