Re: [PATCH v4] platform/x86: alienware-wmi-base: Transition to new WMI API

[Armin Wolf <W_Armin@gmx.de>]

Am 28.04.26 um 18:37 schrieb Kurt Borja:

> Transition to the new wmi_buffer based WMI API.
>
> Signed-off-by: Kurt Borja <kuurtb@gmail.com>
> ---
> v4:
>    - Rebase to use the new wmidev_invoke_method() with size check
>
> v3: https://patch.msgid.link/20260331-aw-new-api-v3-1-ef03b94529d8@gmail.com
>    - Use __free() instead of manual cleanup.
>    - Include <linux/types.h>
>
> v2: https://patch.msgid.link/20260331-aw-new-api-v2-1-3b0d33bf8d22@gmail.com
>    - Cast wmi_buffer data to __le32 and then use le32_to_cpu() before
>      returning
>
> v1: https://patch.msgid.link/20260330-aw-new-api-v1-1-95910bfa1b38@gmail.com
> ---
>   drivers/platform/x86/dell/alienware-wmi-base.c | 31 ++++++++++++++++----------
>   1 file changed, 19 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/platform/x86/dell/alienware-wmi-base.c b/drivers/platform/x86/dell/alienware-wmi-base.c
> index 64562b92314f..21d3acfbd73d 100644
> --- a/drivers/platform/x86/dell/alienware-wmi-base.c
> +++ b/drivers/platform/x86/dell/alienware-wmi-base.c
> @@ -12,8 +12,13 @@
>   #include <linux/cleanup.h>
>   #include <linux/module.h>
>   #include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/types.h>
>   #include <linux/dmi.h>
>   #include <linux/leds.h>
> +
> +#include <asm/byteorder.h>
> +
>   #include "alienware-wmi.h"
>   
>   MODULE_AUTHOR("Mario Limonciello <mario.limonciello@outlook.com>");
> @@ -150,21 +155,23 @@ u8 alienware_interface;
>   int alienware_wmi_command(struct wmi_device *wdev, u32 method_id,
>   			  void *in_args, size_t in_size, u32 *out_data)
>   {
> -	struct acpi_buffer out = {ACPI_ALLOCATE_BUFFER, NULL};
> -	struct acpi_buffer in = {in_size, in_args};
> -	acpi_status ret;
> +	struct wmi_buffer out, in = {
> +		.data = in_args,
> +		.length = in_size,
> +	};
> +	int ret;
>   
> -	ret = wmidev_evaluate_method(wdev, 0, method_id, &in, out_data ? &out : NULL);
> -	if (ACPI_FAILURE(ret))
> -		return -EIO;
> -
> -	union acpi_object *obj __free(kfree) = out.pointer;
> +	if (out_data)
> +		ret = wmidev_invoke_method(wdev, 0, method_id, &in, &out,
> +					   sizeof(*out_data));
> +	else
> +		ret = wmidev_invoke_method(wdev, 0, method_id, &in, NULL, 0);
> +	if (ret)
> +		return ret;
>   
>   	if (out_data) {
> -		if (obj && obj->type == ACPI_TYPE_INTEGER)
> -			*out_data = (u32)obj->integer.value;
> -		else
> -			return -ENOMSG;
> +		__le32 *data __free(kfree) = out.data;
> +		*out_data = le32_to_cpu(*data);
>   	}

Hi,

calling wmidev_invoke_method() with a NULL output buffer will likely lead to crashes. This happens
because wmidev_invoke_method() demands that a valid pointer to a output buffer is provided by the
caller. I suggest that you use wmidev_invoke_procedure() instead:

	__le32 *data __free(kfree) = NULL;

	if (!out_data)
		return wmidev_invoke_procedure(wdev, 0, method_id, &in);

	ret = wmidev_invoke_method(wdev, 0, method_id, &in, &out, sizeof(*data));
	if (ret < 0)
		return ret;

	result = out.data
	...

Thanks,
Armin Wolf

>   
>   	return 0;
>
> ---
> base-commit: 254f49634ee16a731174d2ae34bc50bd5f45e731
> change-id: 20260123-aw-new-api-1c18f1011f35
>