tty: Drop tty->count on tty_reopen() failure

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))

Fixes: commit 892d1fa7eaae ("tty: Destroy ldisc instance on hangup")
Cc: stable@vger.kernel.org # v4.6+
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Reviewed-by: Jiri Slaby <jslaby@suse.cz>
Tested-by: Jiri Slaby <jslaby@suse.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 32bc3e3fe4d30bcea455fb7dc13657b63b111cd9..5e5da9acaf0a9f2522b0b1659968499d91a97e4a 100644 (file)
--- 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;
 }
 
 /**