Re: [PATCH 09/10] vfio/pci: Replace uses of vfio_device_data() with container_of

From: Christoph Hellwig <hch@lst.de>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: Alex Williamson <alex.williamson@redhat.com>,
	Cornelia Huck <cohuck@redhat.com>,
	kvm@vger.kernel.org, "Raj, Ashok" <ashok.raj@intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Daniel Vetter <daniel@ffwll.ch>, Christoph Hellwig <hch@lst.de>,
	Leon Romanovsky <leonro@nvidia.com>,
	Max Gurtovoy <mgurtovoy@nvidia.com>,
	Tarun Gupta <targupta@nvidia.com>
Subject: Re: [PATCH 09/10] vfio/pci: Replace uses of vfio_device_data() with container_of
Date: Wed, 10 Mar 2021 08:36:34 +0100	[thread overview]
Message-ID: <20210310073634.GH2659@lst.de> (raw)
In-Reply-To: <9-v1-7355d38b9344+17481-vfio1_jgg@nvidia.com>

On Tue, Mar 09, 2021 at 05:38:51PM -0400, Jason Gunthorpe wrote:
> This tidies a few confused places that think they can have a refcount on
> the vfio_device but the device_data could be NULL, that isn't possible by
> design.
> 
> Most of the change falls out when struct vfio_devices is updated to just
> store the struct vfio_pci_device itself. This wasn't possible before
> because there was no easy way to get from the 'struct vfio_pci_device' to
> the 'struct vfio_device' to put back the refcount.
> 
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> ---
>  drivers/vfio/pci/vfio_pci.c | 45 ++++++++++++-------------------------
>  1 file changed, 14 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> index af5696a96a76e0..4b0d60f7602e40 100644
> --- a/drivers/vfio/pci/vfio_pci.c
> +++ b/drivers/vfio/pci/vfio_pci.c
> @@ -534,7 +534,7 @@ static struct vfio_pci_device *get_pf_vdev(struct vfio_pci_device *vdev,
>  		return NULL;
>  	}
>  
> -	return vfio_device_data(*pf_dev);
> +	return container_of(*pf_dev, struct vfio_pci_device, vdev);

I think it would be useful to just return the vfio_device and let
the caller do the container_of() here, maybe as a followup.

Otherwise looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>