Re: [PATCH V13 6/6] docs: sample driver to demonstrate how to implement virtio-mdev framework

[Jason Wang]

On 2019/11/18 äå11:45, Cornelia Huck wrote:
> On Mon, 18 Nov 2019 18:59:23 +0800
> Jason Wang <jasowang@xxxxxxxxxx> wrote:
>
> [Note: I have not looked into the reworked architecture of this *at all*
> so far; just something that I noted...]
>
> > This sample driver creates mdev device that simulate virtio net device
> > over virtio mdev transport. The device is implemented through vringh
> > and workqueue. A device specific dma ops is to make sure HVA is used
> > directly as the IOVA. This should be sufficient for kernel virtio
> > driver to work.
> >
> > Only 'virtio' type is supported right now. I plan to add 'vhost' type
> > on top which requires some virtual IOMMU implemented in this sample
> > driver.
> >
> > Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> > ---
> >   MAINTAINERS                        |   1 +
> >   samples/Kconfig                    |  10 +
> >   samples/vfio-mdev/Makefile         |   1 +
> >   samples/vfio-mdev/mvnet_loopback.c | 690 +++++++++++++++++++++++++++++
> >   4 files changed, 702 insertions(+)
> >   create mode 100644 samples/vfio-mdev/mvnet_loopback.c
> >
> > +static struct mvnet_dev {
> > +	struct class	*vd_class;
> > +	struct idr	vd_idr;
> > +	struct device	dev;
> > +} mvnet_dev;
> This structure embeds a struct device (a reference-counted structure),
> yet it is a static variable. This is giving a bad example to potential
> implementers; just allocate it dynamically.


Yes, as spotted by Greg.


> > +static void mvnet_device_release(struct device *dev)
> > +{
> > +	dev_dbg(dev, "mvnet: released\n");
> And that also means you need a proper release function here, of
> course.


Right.

Thanks


> > +}