s390/cio: fix unlocked access of online member

Make sure that access to the online member of a ccw device is
guarded by the ccwlock.

Reported-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/cio/device.c

@@ -333,9 +333,9 @@ int ccw_device_set_offline(struct ccw_device *cdev)
 		if (ret != 0)
 			return ret;
 	}
-	cdev->online = 0;
 	spin_lock_irq(cdev->ccwlock);
 	sch = to_subchannel(cdev->dev.parent);
+	cdev->online = 0;
 	/* Wait until a final state or DISCONNECTED is reached */
 	while (!dev_fsm_final_state(cdev) &&
 	       cdev->private->state != DEV_STATE_DISCONNECTED) {
@@ -446,7 +446,10 @@ int ccw_device_set_online(struct ccw_device *cdev)
 		ret = cdev->drv->set_online(cdev);
 	if (ret)
 		goto rollback;
+
+	spin_lock_irq(cdev->ccwlock);
 	cdev->online = 1;
+	spin_unlock_irq(cdev->ccwlock);
 	return 0;
 
 rollback:
@@ -1745,8 +1748,7 @@ ccw_device_probe (struct device *dev)
 	return 0;
 }
 
-static int
-ccw_device_remove (struct device *dev)
+static int ccw_device_remove(struct device *dev)
 {
 	struct ccw_device *cdev = to_ccwdev(dev);
 	struct ccw_driver *cdrv = cdev->drv;
@@ -1754,9 +1756,10 @@ ccw_device_remove (struct device *dev)
 
 	if (cdrv->remove)
 		cdrv->remove(cdev);
+
+	spin_lock_irq(cdev->ccwlock);
 	if (cdev->online) {
 		cdev->online = 0;
-		spin_lock_irq(cdev->ccwlock);
 		ret = ccw_device_offline(cdev);
 		spin_unlock_irq(cdev->ccwlock);
 		if (ret == 0)
@@ -1769,10 +1772,12 @@ ccw_device_remove (struct device *dev)
 				      cdev->private->dev_id.devno);
 		/* Give up reference obtained in ccw_device_set_online(). */
 		put_device(&cdev->dev);
+		spin_lock_irq(cdev->ccwlock);
 	}
 	ccw_device_set_timeout(cdev, 0);
 	cdev->drv = NULL;
 	cdev->private->int_class = IRQIO_CIO;
+	spin_unlock_irq(cdev->ccwlock);
 	return 0;
 }