vfio: Fix container device registration life cycle

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2155664
Conflicts: Semaphore vs mutex context since we don't yet include
           c82e81a ("vfio: Change vfio_group->group_rwsem to a mutex")

commit 7fdba00
Author: Anthony DeRossi <ajderossi@gmail.com>
Date:   Wed Nov 9 17:40:25 2022 -0800

    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>

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

Author: Alex Williamson

drivers/vfio/vfio_main.c

@@ -1172,8 +1172,9 @@ static struct file *vfio_device_open(struct vfio_device *device)
 err_close_device:
 	mutex_lock(&device->dev_set->lock);
 	down_read(&device->group->group_rwsem);
-	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);
 	}
@@ -1375,10 +1376,12 @@ static int vfio_device_fops_release(struct inode *inode, struct file *filep)
 	mutex_lock(&device->dev_set->lock);
 	vfio_assert_device_open(device);
 	down_read(&device->group->group_rwsem);
-	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);
+	}
 	up_read(&device->group->group_rwsem);
 	device->open_count--;
 	if (device->open_count == 0)