vfio/ap/ccw/samples: Fix device_register() unwind path

We always need to call put_device() if device_register() fails.
All vfio drivers calling device_register() include a similar unwind
stack via gotos, therefore split device_unregister() into its
device_del() and put_device() components in the unwind path, and
add a goto target to handle only the put_device() requirement.
Reported-by: Ruan Jinjie <ruanjinjie@huawei.com>
Link: https://lore.kernel.org/all/20221118032827.3725190-1-ruanjinjie@huawei.com
Fixes: d61fc96f ("sample: vfio mdev display - host device")
Fixes: 9d1a546c ("docs: Sample driver to demonstrate how to use Mediated device framework.")
Fixes: a5e6e650 ("sample: vfio bochs vbe display (host device for bochs-drm)")
Fixes: 9e6f07cd ("vfio/ccw: create a parent struct")
Fixes: 36360658 ("s390: vfio_ap: link the vfio_ap devices to the vfio_ap bus subsystem")
Cc: Tony Krowiak <akrowiak@linux.ibm.com>
Cc: Halil Pasic <pasic@linux.ibm.com>
Cc: Jason Herne <jjherne@linux.ibm.com>
Cc: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Tony Krowiak <akrowiak@linux.ibm.com>
Reviewed-by: Jason J. Herne <jjherne@linux.ibm.com>
Link: https://lore.kernel.org/r/166999942139.645727.12439756512449846442.stgit@omenSigned-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/s390/cio/vfio_ccw_drv.c

@@ -199,8 +199,9 @@ static int vfio_ccw_sch_probe(struct subchannel *sch)
 	return 0;
 
 out_unreg:
-	device_unregister(&parent->dev);
+	device_del(&parent->dev);
 out_free:
+	put_device(&parent->dev);
 	dev_set_drvdata(&sch->dev, NULL);
 	return ret;
 }

drivers/s390/crypto/vfio_ap_drv.c

@@ -122,7 +122,7 @@ static int vfio_ap_matrix_dev_create(void)
 	return 0;
 
 matrix_drv_err:
-	device_unregister(&matrix_dev->device);
+	device_del(&matrix_dev->device);
 matrix_reg_err:
 	put_device(&matrix_dev->device);
 matrix_alloc_err:

samples/vfio-mdev/mbochs.c

@@ -1430,7 +1430,7 @@ static int __init mbochs_dev_init(void)
 
 	ret = device_register(&mbochs_dev);
 	if (ret)
-		goto err_class;
+		goto err_put;
 
 	ret = mdev_register_parent(&mbochs_parent, &mbochs_dev, &mbochs_driver,
 				   mbochs_mdev_types,
@@ -1441,8 +1441,9 @@ static int __init mbochs_dev_init(void)
 	return 0;
 
 err_device:
-	device_unregister(&mbochs_dev);
-err_class:
+	device_del(&mbochs_dev);
+err_put:
+	put_device(&mbochs_dev);
 	class_destroy(mbochs_class);
 err_driver:
 	mdev_unregister_driver(&mbochs_driver);

samples/vfio-mdev/mdpy.c

@@ -717,7 +717,7 @@ static int __init mdpy_dev_init(void)
 
 	ret = device_register(&mdpy_dev);
 	if (ret)
-		goto err_class;
+		goto err_put;
 
 	ret = mdev_register_parent(&mdpy_parent, &mdpy_dev, &mdpy_driver,
 				   mdpy_mdev_types,
@@ -728,8 +728,9 @@ static int __init mdpy_dev_init(void)
 	return 0;
 
 err_device:
-	device_unregister(&mdpy_dev);
-err_class:
+	device_del(&mdpy_dev);
+err_put:
+	put_device(&mdpy_dev);
 	class_destroy(mdpy_class);
 err_driver:
 	mdev_unregister_driver(&mdpy_driver);

samples/vfio-mdev/mtty.c

@@ -1330,7 +1330,7 @@ static int __init mtty_dev_init(void)
 
 	ret = device_register(&mtty_dev.dev);
 	if (ret)
-		goto err_class;
+		goto err_put;
 
 	ret = mdev_register_parent(&mtty_dev.parent, &mtty_dev.dev,
 				   &mtty_driver, mtty_mdev_types,
@@ -1340,8 +1340,9 @@ static int __init mtty_dev_init(void)
 	return 0;
 
 err_device:
-	device_unregister(&mtty_dev.dev);
-err_class:
+	device_del(&mtty_dev.dev);
+err_put:
+	put_device(&mtty_dev.dev);
 	class_destroy(mtty_dev.vd_class);
 err_driver:
 	mdev_unregister_driver(&mtty_driver);