serial: core: fix crash in uart_suspend_port

commit 88e2582e90bb89fe895ff0dceeb5d5ab65d07997 upstream.

With serdev we might end up with serial ports that have no cdev exported
to userspace, as they are used as the bus interface to other devices. In
that case serial_match_port() won't be able to find a matching tty_dev.

Skip the irq wakeup enabling in that case, as serdev will make sure to
keep the port active, as long as there are devices depending on it.

Fixes: 8ee3fde04758 (tty_port: register tty ports with serdev bus)
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 3fe56894974a7c4c3ae04a4d54946043be1d243c..7f9139445f2af56459c4a6aab16ecc1f43a5825a 100644 (file)
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -2083,7 +2083,7 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport)
        mutex_lock(&port->mutex);
 
        tty_dev = device_find_child(uport->dev, &match, serial_match_port);
-       if (device_may_wakeup(tty_dev)) {
+       if (tty_dev && device_may_wakeup(tty_dev)) {
                if (!enable_irq_wake(uport->irq))
                        uport->irq_wake = 1;
                put_device(tty_dev);