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Date:   Tue, 6 Jul 2021 06:59:54 +0300
From:   Leon Romanovsky <leon@kernel.org>
To:     Jason Gunthorpe <jgg@nvidia.com>
Cc:     Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>,
        Max Gurtovoy <mgurtovoy@nvidia.com>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
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        "linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
        "alex.williamson@redhat.com" <alex.williamson@redhat.com>,
        Linuxarm <linuxarm@huawei.com>,
        liulongfang <liulongfang@huawei.com>,
        "Zengtao (B)" <prime.zeng@hisilicon.com>,
        yuzenghui <yuzenghui@huawei.com>,
        Jonathan Cameron <jonathan.cameron@huawei.com>,
        "Wangzhou (B)" <wangzhou1@hisilicon.com>
Subject: Re: [RFC v2 1/4] hisi-acc-vfio-pci: add new vfio_pci driver for
 HiSilicon ACC devices
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On Mon, Jul 05, 2021 at 03:32:47PM -0300, Jason Gunthorpe wrote:
> On Mon, Jul 05, 2021 at 09:27:37PM +0300, Leon Romanovsky wrote:
> 
> > > I think, in any case, it would be good to update the Documentation based on
> > > which way we end up doing this.
> > 
> > The request to update Documentation can be seen as an example of
> > choosing not-good API decisions. Expectation to see all drivers to
> > use same callbacks with same vfio-core function calls sounds strange
> > to me.
> 
> It is not vfio-core, it is vfio-pci-core. It is similar to how some of
> the fops stuff works, eg the generic_file whatever functions everyone
> puts in.

It doesn't really matter if it is vfio-core or vfio-pci-core. This looks
horrible and it is going to be repeated for every driver:

+       .release        = vfio_pci_core_release,
+       .ioctl          = vfio_pci_core_ioctl,
+       .read           = vfio_pci_core_read,
+       .write          = vfio_pci_core_write,
+       .mmap           = vfio_pci_core_mmap,
+       .request        = vfio_pci_core_request,
+       .match          = vfio_pci_core_match,
+       .reflck_attach  = vfio_pci_core_reflck_attach,
+};

At some point of time you will add new .XXX callback and will
find yourself changing all drivers to have something like
".XXX = vfio_pci_core_XXX,"

Thanks