USB: serial: usb_wwan: use irqsave() in USB's complete callback

The USB completion callback does not disable interrupts while acquiring
the lock. We want to remove the local_irq_disable() invocation from
__usb_hcd_giveback_urb() and therefore it is required for the callback
handler to disable the interrupts while acquiring the lock.
The callback may be invoked either in IRQ or BH context depending on the
USB host controller.
Use the _irqsave() variant of the locking primitives.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Johan Hovold <johan@kernel.org>

drivers/usb/serial/usb_wwan.c

@@ -326,6 +326,7 @@ static void usb_wwan_outdat_callback(struct urb *urb)
 	struct usb_serial_port *port;
 	struct usb_wwan_port_private *portdata;
 	struct usb_wwan_intf_private *intfdata;
+	unsigned long flags;
 	int i;
 
 	port = urb->context;
@@ -334,9 +335,9 @@ static void usb_wwan_outdat_callback(struct urb *urb)
 	usb_serial_port_softint(port);
 	usb_autopm_put_interface_async(port->serial->interface);
 	portdata = usb_get_serial_port_data(port);
-	spin_lock(&intfdata->susp_lock);
+	spin_lock_irqsave(&intfdata->susp_lock, flags);
 	intfdata->in_flight--;
-	spin_unlock(&intfdata->susp_lock);
+	spin_unlock_irqrestore(&intfdata->susp_lock, flags);
 
 	for (i = 0; i < N_OUT_URB; ++i) {
 		if (portdata->out_urbs[i] == urb) {