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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>,
        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>,
        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>,
        Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org
Subject: [PATCHv2 1/4] tty: Drop tty->count on tty_reopen() failure
Date:   Mon,  3 Sep 2018 17:52:54 +0100
Message-Id: <20180903165257.29227-2-dima@arista.com>
In-Reply-To: <20180903165257.29227-1-dima@arista.com>
References: <20180903165257.29227-1-dima@arista.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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