vfio: Fix container device registration life cycle

In vfio_device_open(), vfio_device_container_register() is always called
when open_count == 1. On error, vfio_device_container_unregister() is
only called when open_count == 1 and close_device is set. This leaks a
registration for devices without a close_device implementation.

In vfio_device_fops_release(), vfio_device_container_unregister() is
called unconditionally. This can cause a device to be unregistered
multiple times.

Treating container device registration/unregistration uniformly (always
when open_count == 1) fixes both issues.

Fixes: ce4b465 ("vfio: Replace the DMA unmapping notifier with a callback")
Signed-off-by: Anthony DeRossi <ajderossi@gmail.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Yi Liu <yi.l.liu@intel.com>
Link: https://lore.kernel.org/r/20221110014027.28780-2-ajderossi@gmail.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/vfio/vfio_main.c

@@ -801,8 +801,9 @@ static struct file *vfio_device_open(struct vfio_device *device)
 err_close_device:
 	mutex_lock(&device->dev_set->lock);
 	mutex_lock(&device->group->group_lock);
-	if (device->open_count == 1 && device->ops->close_device) {
-		device->ops->close_device(device);
+	if (device->open_count == 1) {
+		if (device->ops->close_device)
+			device->ops->close_device(device);
 
 		vfio_device_container_unregister(device);
 	}
@@ -1017,10 +1018,12 @@ static int vfio_device_fops_release(struct inode *inode, struct file *filep)
 	mutex_lock(&device->dev_set->lock);
 	vfio_assert_device_open(device);
 	mutex_lock(&device->group->group_lock);
-	if (device->open_count == 1 && device->ops->close_device)
-		device->ops->close_device(device);
+	if (device->open_count == 1) {
+		if (device->ops->close_device)
+			device->ops->close_device(device);
 
-	vfio_device_container_unregister(device);
+		vfio_device_container_unregister(device);
+	}
 	mutex_unlock(&device->group->group_lock);
 	device->open_count--;
 	if (device->open_count == 0)