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Subject: [PATCH] vfio/ap/ccw/samples: Fix device_register() unwind path
From:   Alex Williamson <alex.williamson@redhat.com>
To:     alex.williamson@redhat.com
Cc:     ruanjinjie <ruanjinjie@huawei.com>,
        Tony Krowiak <akrowiak@linux.ibm.com>,
        Halil Pasic <pasic@linux.ibm.com>,
        Jason Herne <jjherne@linux.ibm.com>,
        Kirti Wankhede <kwankhede@nvidia.com>,
        Kevin Tian <kevin.tian@intel.com>,
        Eric Farman <farman@linux.ibm.com>, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org
Date:   Fri, 02 Dec 2022 09:46:15 -0700
Message-ID: <166999942139.645727.12439756512449846442.stgit@omen>
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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: d61fc96f47fd ("sample: vfio mdev display - host device")
Fixes: 9d1a546c53b4 ("docs: Sample driver to demonstrate how to use Mediated device framework.")
Fixes: a5e6e6505f38 ("sample: vfio bochs vbe display (host device for bochs-drm)")
Fixes: 9e6f07cd1eaa ("vfio/ccw: create a parent struct")
Fixes: 36360658eb5a ("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>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---

I didn't intend to usurp Ruan's patch, but since the inline version is
collecting reviews, formally post it and include additional fixes tags
for vfio-ccw and vfio-ap.

 drivers/s390/cio/vfio_ccw_drv.c   |    3 ++-
 drivers/s390/crypto/vfio_ap_drv.c |    2 +-
 samples/vfio-mdev/mbochs.c        |    7 ++++---
 samples/vfio-mdev/mdpy.c          |    7 ++++---
 samples/vfio-mdev/mtty.c          |    7 ++++---
 5 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c
index c2a65808605a..54aba7cceb33 100644
--- a/drivers/s390/cio/vfio_ccw_drv.c
+++ b/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;
 }
diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
index f43cfeabd2cc..997b524bdd2b 100644
--- a/drivers/s390/crypto/vfio_ap_drv.c
+++ b/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:
diff --git a/samples/vfio-mdev/mbochs.c b/samples/vfio-mdev/mbochs.c
index 8b5a3a778a25..e54eb752e1ba 100644
--- a/samples/vfio-mdev/mbochs.c
+++ b/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);
diff --git a/samples/vfio-mdev/mdpy.c b/samples/vfio-mdev/mdpy.c
index 721fb06c6413..e8400fdab71d 100644
--- a/samples/vfio-mdev/mdpy.c
+++ b/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);
diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c
index 3c2a421b9b69..e887de672c52 100644
--- a/samples/vfio-mdev/mtty.c
+++ b/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);