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

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On 2020/2/11 下午9:52, 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






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