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SubjectRe: [PATCH V2 5/5] vdpasim: vDPA device simulator
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.

> + 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

> +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

> +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

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

Jason

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