Re: [PATCH v6 3/4] iommufd: Add IOMMU_GET_HW_INFO

Baolu Lu
2023-08-09T10:16:33Z

On 2023/8/8 23:35, Yi Liu wrote:
> +static int iommufd_fill_hw_info(struct device *dev, void __user *user_ptr,
> + unsigned int *length, u32 *type)
> +{
> + const struct iommu_ops *ops;
> + unsigned int data_len;
> + void *data;
> + int rc = 0;
> +
> + ops = dev_iommu_ops(dev);
> + if (!ops->hw_info) {
> + *length = 0;
> + *type = IOMMU_HW_INFO_TYPE_NONE;
> + return 0;
> + }
> +
> + data = ops->hw_info(dev, &data_len, type);
> + if (IS_ERR(data))
> + return PTR_ERR(data);
> +
> + /*
> + * drivers that have hw_info callback should have a unique
> + * iommu_hw_info_type.
> + */
> + if (WARN_ON_ONCE(*type == IOMMU_HW_INFO_TYPE_NONE)) {
> + rc = -ENODEV;
> + goto err_free;
> + }
> +
> + *length = min(*length, data_len);
> + if (copy_to_user(user_ptr, data, *length)) {

copy_to_user() returns the number of bytes that were successfully
copied, right?

If so, isn't it always failure case? Or I missed anything?

> + rc = -EFAULT;
> + goto err_free;

nit: this goto is unnecessary.

> + }
> +
> +err_free:
> + kfree(data);
> + return rc;
> +}

Best regards,
baolu