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SubjectRe: [PATCH v2 2/3] platform/x86: wmi: add WMI support to MODULE_DEVICE_TABLE()
On Sun, Jan 27, 2019 at 9:04 PM Mattias Jacobsson <2pi@mok.nu> wrote:
>
> The kernel provides the macro MODULE_DEVICE_TABLE() where driver authors
> can specify their device type and their array of device_ids and thereby
> trigger the generation of the appropriate MODULE_ALIAS() output. This is
> opposed to having to specify one MODULE_ALIAS() for each device. The WMI
> device type is currently not supported.
>
> While using MODULE_DEVICE_TABLE() does increase the complexity as well
> as spreading out the implementation across the kernel, it does come with
> some benefits too;
> * It makes different drivers look more similar; if you can specify the
> array of device_ids any device type specific input to MODULE_ALIAS()
> will automatically be generated for you.
> * It helps each driver avoid keeping multiple versions of the same
> information in sync. That is, both the array of device_ids and the
> potential multitude of MODULE_ALIAS()'s.
>
> Add WMI support to MODULE_DEVICE_TABLE() by adding info about struct
> wmi_device_id in devicetable-offsets.c and add a WMI entry point in
> file2alias.c.
>
> The type argument for MODULE_DEVICE_TABLE(type, name) is wmi.

> +/* Looks like: wmi:guid */
> +static int do_wmi_entry(const char *filename, void *symval, char *alias)
> +{
> + DEF_FIELD_ADDR(symval, wmi_device_id, guid_string);
> + if (strlen(*guid_string) != WMI_GUID_STRING_LEN) {
> + warn("Invalid WMI device id 'wmi:%s' in '%s'\n",
> + *guid_string, filename);
> + return 0;
> + }

> + if (snprintf(alias, 500, WMI_MODULE_PREFIX "%s", *guid_string) < 0) {

What the point to use snprintf here with arbitrary buffer size if we
exactly know 2 facts:
1. UUID string is 36 characters
2. buffer is long enough

?

> + warn("Could not generate all MODULE_ALIAS's in '%s'\n",
> + filename);
> + return 0;
> + }
> + return 1;
> +}

--
With Best Regards,
Andy Shevchenko

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