linux-kernel - Re: [PATCH] vfio/ap/ccw/samples: Fix device

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Date:   Mon, 5 Dec 2022 08:39:52 -0500
From:   "Jason J. Herne" <jjherne@...ux.ibm.com>
To:     Alex Williamson <alex.williamson@...hat.com>
Cc:     ruanjinjie <ruanjinjie@...wei.com>,
        Tony Krowiak <akrowiak@...ux.ibm.com>,
        Halil Pasic <pasic@...ux.ibm.com>,
        Kirti Wankhede <kwankhede@...dia.com>,
        Kevin Tian <kevin.tian@...el.com>,
        Eric Farman <farman@...ux.ibm.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] vfio/ap/ccw/samples: Fix device_register() unwind path



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@...wei.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@...ux.ibm.com>
> Cc: Halil Pasic <pasic@...ux.ibm.com>
> Cc: Jason Herne <jjherne@...ux.ibm.com>
> Cc: Kirti Wankhede <kwankhede@...dia.com>
> Reviewed-by: Kevin Tian <kevin.tian@...el.com>
> Reviewed-by: Eric Farman <farman@...ux.ibm.com>
> Signed-off-by: Alex Williamson <alex.williamson@...hat.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/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:

Reviewed-by: Jason J. Herne <jjherne@...ux.ibm.com>