serial: core: fix crash in uart_suspend_port

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>
Cc: stable <stable@vger.kernel.org>
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 0f45b7884a2c58a299668591e87bead1f6628f98..bc6caea6099f4f9693415b055711187001e09a55 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);