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Date:   Fri, 28 Oct 2022 14:43:01 -0400
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Subject: Re: [PATCH v1 2/7] vfio/ccw: remove private->sch
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To:     Eric Farman <farman@linux.ibm.com>,
        Alex Williamson <alex.williamson@redhat.com>,
        Cornelia Huck <cohuck@redhat.com>,
        Jason Gunthorpe <jgg@nvidia.com>,
        Kevin Tian <kevin.tian@intel.com>, Yi Liu <yi.l.liu@intel.com>
Cc:     Zhenyu Wang <zhenyuw@linux.intel.com>,
        Zhi Wang <zhi.a.wang@intel.com>,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>,
        Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Halil Pasic <pasic@linux.ibm.com>,
        Vineeth Vijayan <vneethv@linux.ibm.com>,
        Peter Oberparleiter <oberpar@linux.ibm.com>,
        Heiko Carstens <hca@linux.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Alexander Gordeev <agordeev@linux.ibm.com>,
        Christian Borntraeger <borntraeger@linux.ibm.com>,
        Sven Schnelle <svens@linux.ibm.com>,
        Tony Krowiak <akrowiak@linux.ibm.com>,
        Jason Herne <jjherne@linux.ibm.com>,
        Harald Freudenberger <freude@linux.ibm.com>,
        Diana Craciun <diana.craciun@oss.nxp.com>,
        Eric Auger <eric.auger@redhat.com>,
        Kirti Wankhede <kwankhede@nvidia.com>,
        Abhishek Sahu <abhsahu@nvidia.com>,
        Yishai Hadas <yishaih@nvidia.com>,
        intel-gvt-dev@lists.freedesktop.org,
        intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
        kvm@vger.kernel.org
References: <20221019162135.798901-1-farman@linux.ibm.com>
 <20221019162135.798901-3-farman@linux.ibm.com>
From:   Matthew Rosato <mjrosato@linux.ibm.com>
In-Reply-To: <20221019162135.798901-3-farman@linux.ibm.com>
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On 10/19/22 12:21 PM, Eric Farman wrote:
> These places all rely on the ability to jump from a private
> struct back to the subchannel struct. Rather than keeping a
> copy in our back pocket, let's use the relationship provided
> by the vfio_device embedded within the private.
> 
> Signed-off-by: Eric Farman <farman@linux.ibm.com>
> ---
>  drivers/s390/cio/vfio_ccw_chp.c     |  5 +++--
>  drivers/s390/cio/vfio_ccw_drv.c     |  3 +--
>  drivers/s390/cio/vfio_ccw_fsm.c     | 27 ++++++++++++---------------
>  drivers/s390/cio/vfio_ccw_ops.c     | 12 ++++++------
>  drivers/s390/cio/vfio_ccw_private.h |  7 ++++---
>  5 files changed, 26 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/s390/cio/vfio_ccw_chp.c b/drivers/s390/cio/vfio_ccw_chp.c
> index 13b26a1c7988..d3f3a611f95b 100644
> --- a/drivers/s390/cio/vfio_ccw_chp.c
> +++ b/drivers/s390/cio/vfio_ccw_chp.c
> @@ -16,6 +16,7 @@ static ssize_t vfio_ccw_schib_region_read(struct vfio_ccw_private *private,
>  					  char __user *buf, size_t count,
>  					  loff_t *ppos)
>  {
> +	struct subchannel *sch = to_subchannel(private->vdev.dev->parent);

I'm not a big fan of the amount of indirection there, but I prefer this over back-pocketing the subchannel in vfio_ccw_private anyway

Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>