Re: [PATCH V2 5/5] vdpasim: vDPA device simulator

[Jason Wang]

On 2020/2/11 äå9:52, Jason Gunthorpe wrote:
> On Mon, Feb 10, 2020 at 11:56:08AM +0800, Jason Wang wrote:
> > +
> > +static struct vdpasim *vdpasim_create(void)
> > +{
> > +	struct vdpasim *vdpasim;
> > +	struct virtio_net_config *config;
> > +	struct vdpa_device *vdpa;
> > +	struct device *dev;
> > +	int ret = -ENOMEM;
> > +
> > +	vdpasim = kzalloc(sizeof(*vdpasim), GFP_KERNEL);
> > +	if (!vdpasim)
> > +		goto err_vdpa_alloc;
> > +
> > +	vdpasim->buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
> > +	if (!vdpasim->buffer)
> > +		goto err_buffer_alloc;
> > +
> > +	vdpasim->iommu = vhost_iotlb_alloc(2048, 0);
> > +	if (!vdpasim->iommu)
> > +		goto err_iotlb;
> > +
> > +	config = &vdpasim->config;
> > +	config->mtu = 1500;
> > +	config->status = VIRTIO_NET_S_LINK_UP;
> > +	eth_random_addr(config->mac);
> > +
> > +	INIT_WORK(&vdpasim->work, vdpasim_work);
> > +	spin_lock_init(&vdpasim->lock);
> > +
> > +	vdpa = &vdpasim->vdpa;
> > +	vdpa->dev.release = vdpasim_release_dev;
> The driver should not provide the release function.
>
> Again the safest model is 'vdpa_alloc_device' which combines the
> kzalloc and the vdpa_init_device() and returns something that is
> error unwound with put_device()
>
> The subsystem owns the release and does the kfree and other cleanup
> like releasing the IDA.


So I think if we agree bus instead of class is used. vDPA bus can 
provide a release function in vdpa_alloc_device()?


> > +	vringh_set_iotlb(&vdpasim->vqs[0].vring, vdpasim->iommu);
> > +	vringh_set_iotlb(&vdpasim->vqs[1].vring, vdpasim->iommu);
> > +
> > +	dev = &vdpa->dev;
> > +	dev->coherent_dma_mask = DMA_BIT_MASK(64);
> > +	set_dma_ops(dev, &vdpasim_dma_ops);
> > +
> > +	ret = vdpa_init_device(vdpa, &vdpasim_dev->dev, dev,
> > +			       &vdpasim_net_config_ops);
> > +	if (ret)
> > +		goto err_init;
> > +
> > +	ret = vdpa_register_device(vdpa);
> > +	if (ret)
> > +		goto err_register;
> See? This error unwind is now all wrong:
>
> > +
> > +	return vdpasim;
> > +
> > +err_register:
> > +	put_device(&vdpa->dev);
> Double put_device


Yes.


> > +err_init:
> > +	vhost_iotlb_free(vdpasim->iommu);
> > +err_iotlb:
> > +	kfree(vdpasim->buffer);
> > +err_buffer_alloc:
> > +	kfree(vdpasim);
> kfree after vdpa_init_device() is incorrect, as the put_device now
> does kfree via release


Ok, will fix.


> > +static int __init vdpasim_dev_init(void)
> > +{
> > +	struct device *dev;
> > +	int ret = 0;
> > +
> > +	vdpasim_dev = kzalloc(sizeof(*vdpasim_dev), GFP_KERNEL);
> > +	if (!vdpasim_dev)
> > +		return -ENOMEM;
> > +
> > +	dev = &vdpasim_dev->dev;
> > +	dev->release = vdpasim_device_release;
> > +	dev_set_name(dev, "%s", VDPASIM_NAME);
> > +
> > +	ret = device_register(&vdpasim_dev->dev);
> > +	if (ret)
> > +		goto err_register;
> > +
> > +	if (!vdpasim_create())
> > +		goto err_register;
> Wrong error unwind here too


Will fix.

Thanks


> > +	return 0;
> > +
> > +err_register:
> > +	kfree(vdpasim_dev);
> > +	vdpasim_dev = NULL;
> > +	return ret;
> > +}
> Jason