linux-kernel - Re: [PATCH 5/6] iommu/amd: Add support for non-pci devices

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Date:	Thu, 7 Jan 2016 13:04:22 +0100
From:	Joerg Roedel <joro@...tes.org>
To:	Wan Zongshun <vincent.wan@....com>
Cc:	iommu@...ts.linux-foundation.org,
	Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>,
	Borislav Petkov <bp@...e.de>, Ray Huang <ray.huang@....com>,
	ken.xue@....com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/6] iommu/amd: Add support for non-pci devices

On Tue, Jan 05, 2016 at 05:07:23AM -0500, Wan Zongshun wrote:
> -static inline u16 get_device_id(struct device *dev)
> +static inline int match_hid_uid(struct device *dev,
> +				struct acpihid_map_entry *entry)
> +{
> +	const char *hid, *uid;
> +
> +	hid = acpi_device_hid(ACPI_COMPANION(dev));
> +	uid = acpi_device_uid(ACPI_COMPANION(dev));
> +
> +	if (!hid || !(*hid))
> +		return -ENODEV;
> +
> +	if (!uid || !(*uid))
> +		return strcmp(hid, entry->hid);
> +
> +	if (!(*entry->uid))
> +		return strcmp(hid, entry->hid);
> +
> +	return -ENODEV;
> +}
> +
> +static inline u16 get_pci_device_id(struct device *dev)
>  {
>  	struct pci_dev *pdev = to_pci_dev(dev);
>  
>  	return PCI_DEVID(pdev->bus->number, pdev->devfn);
>  }
>  
> +static inline int get_acpihid_device_id(struct device *dev,
> +					struct acpihid_map_entry **entry)
> +{
> +	struct acpihid_map_entry *p;
> +
> +	list_for_each_entry(p, &acpihid_map, list) {
> +		if (!match_hid_uid(dev, p)) {
> +			if (entry)
> +				*entry = p;
> +			return p->devid;
> +		}
> +	}
> +	return -EINVAL;
> +}
> +
> +static inline u16 get_device_id(struct device *dev)
> +{
> +	if (dev_is_pci(dev))
> +		return get_pci_device_id(dev);
> +	else
> +		return get_acpihid_device_id(dev, NULL);
> +}

This is not robust, get_acpihid_device_id() returns int and can return a
negative value. This gets lost when converting it to u16 here. So either
you add error handling for get_acpihid_device_id() in get_device_id() or
you change get_device_id() to return int too and handle the error at the
callers of get_device_id().


	Joerg

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