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Date:   Mon, 5 Dec 2022 15:36:23 -0700
From:   Alex Williamson <alex.williamson@redhat.com>
To:     Anthony Krowiak <akrowiak@linux.ibm.com>
Cc:     ruanjinjie <ruanjinjie@huawei.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
Subject: Re: [PATCH] vfio/ap/ccw/samples: Fix device_register() unwind path
Message-ID: <20221205153623.6a5bf415.alex.williamson@redhat.com>
In-Reply-To: <9fe1e000-e3ff-bf42-28f7-169fb57dc1ce@linux.ibm.com>
References: <166999942139.645727.12439756512449846442.stgit@omen>
        <9fe1e000-e3ff-bf42-28f7-169fb57dc1ce@linux.ibm.com>
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On Mon, 5 Dec 2022 14:20:53 -0500
Anthony Krowiak <akrowiak@linux.ibm.com> wrote:

> Reviewed-by: Tony Krowiak <akrowiak@linux.ibm.com>
> 
> On 12/2/22 11:46 AM, Alex Williamson wrote:
> > 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>
> > ---

With all the ccw and ap acks, applied to vfio next branch for v6.2.
Thanks,

Alex

> >
> > 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);
> >
> >  
>