[PATCH 4.14 138/178] serdev: ttyport: enforce tty-driver open() requirement

[Greg Kroah-Hartman]

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Johan Hovold <johan@xxxxxxxxxx>


[ Upstream commit dee7d0f3b200c67c6ee96bd37c6e8fa52690ab56 ]

The tty-driver open routine is mandatory, but the serdev
tty-port-controller implementation did not treat it as such and would
instead fall back to calling tty_port_open() directly.

Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Acked-by: Rob Herring <robh@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/tty/serdev/serdev-ttyport.c |   14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

--- a/drivers/tty/serdev/serdev-ttyport.c
+++ b/drivers/tty/serdev/serdev-ttyport.c
@@ -120,10 +120,10 @@ static int ttyport_open(struct serdev_co
 		return PTR_ERR(tty);
 	serport->tty = tty;
 
-	if (tty->ops->open)
-		tty->ops->open(serport->tty, NULL);
-	else
-		tty_port_open(serport->port, tty, NULL);
+	if (!tty->ops->open)
+		goto err_unlock;
+
+	tty->ops->open(serport->tty, NULL);
 
 	/* Bring the UART into a known 8 bits no parity hw fc state */
 	ktermios = tty->termios;
@@ -140,6 +140,12 @@ static int ttyport_open(struct serdev_co
 
 	tty_unlock(serport->tty);
 	return 0;
+
+err_unlock:
+	tty_unlock(tty);
+	tty_release_struct(tty, serport->tty_idx);
+
+	return -ENODEV;
 }
 
 static void ttyport_close(struct serdev_controller *ctrl)