Re: [PATCH v3 4/9] platform/wmi: Add kunit test for the string conversion code

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

On Fri, 9 Jan 2026, Armin Wolf wrote:

> The string conversion frunctions provided by the WMI driver core
> have no dependencies on the remaining WMI API, making them suitable
> for unit tests.
> 
> Implement such a unit test using kunit. Those unit tests verify that
> converting between WMI strings and UTF8 strings works as expected.
> They also verify that edge cases are handled correctly.
> 
> Signed-off-by: Armin Wolf <W_Armin@gmx.de>
> ---
>  drivers/platform/wmi/tests/Kconfig        |  11 +
>  drivers/platform/wmi/tests/Makefile       |   3 +
>  drivers/platform/wmi/tests/string_kunit.c | 278 ++++++++++++++++++++++
>  3 files changed, 292 insertions(+)
>  create mode 100644 drivers/platform/wmi/tests/string_kunit.c
> 
> diff --git a/drivers/platform/wmi/tests/Kconfig b/drivers/platform/wmi/tests/Kconfig
> index efcbcb51c251..f7f0f3c540f5 100644
> --- a/drivers/platform/wmi/tests/Kconfig
> +++ b/drivers/platform/wmi/tests/Kconfig
> @@ -14,3 +14,14 @@ config ACPI_WMI_MARSHALLING_KUNIT_TEST
>  	  to the KUnit documentation in Documentation/dev-tools/kunit/.
>  
>  	  If unsure, say N.
> +
> +config ACPI_WMI_STRING_KUNIT_TEST
> +	tristate "KUnit Test for ACPI-WMI string conversion" if !KUNIT_ALL_TESTS
> +	depends on KUNIT
> +	default KUNIT_ALL_TESTS
> +	help
> +	  This builds unit tests for the ACPI-WMI string conversion code.
> +	  For more information on KUnit and unit tests in general, please refer
> +	  to the KUnit documentation in Documentation/dev-tools/kunit/.
> +
> +	  If unsure, say N.
> diff --git a/drivers/platform/wmi/tests/Makefile b/drivers/platform/wmi/tests/Makefile
> index 252c3125353a..62c438e26259 100644
> --- a/drivers/platform/wmi/tests/Makefile
> +++ b/drivers/platform/wmi/tests/Makefile
> @@ -6,3 +6,6 @@
>  
>  wmi_marshalling_kunit-y				:= marshalling_kunit.o
>  obj-$(CONFIG_ACPI_WMI_MARSHALLING_KUNIT_TEST)	+= wmi_marshalling_kunit.o
> +
> +wmi_string_kunit-y				:= string_kunit.o
> +obj-$(CONFIG_ACPI_WMI_STRING_KUNIT_TEST)	+= wmi_string_kunit.o
> diff --git a/drivers/platform/wmi/tests/string_kunit.c b/drivers/platform/wmi/tests/string_kunit.c
> new file mode 100644
> index 000000000000..9aa3ffa85090
> --- /dev/null
> +++ b/drivers/platform/wmi/tests/string_kunit.c
> @@ -0,0 +1,278 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * KUnit test for the ACPI-WMI string conversion code.
> + *
> + * Copyright (C) 2025 Armin Wolf <W_Armin@gmx.de>
> + */
> +
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/string.h>
> +#include <linux/wmi.h>
> +
> +#include <kunit/resource.h>
> +#include <kunit/test.h>
> +
> +#include <asm/byteorder.h>
> +
> +struct wmi_string_param {
> +	const char *name;
> +	const struct wmi_string *wmi_string;
> +	/*
> +	 * Remember that using sizeof() on a struct wmi_string will
> +	 * always return a size of two bytes due to the flexible
> +	 * array member!
> +	 */
> +	size_t wmi_string_length;
> +	const u8 *utf8_string;
> +	size_t utf8_string_length;
> +};
> +
> +#define TEST_WMI_STRING_LENGTH 12
> +
> +static const struct wmi_string test_wmi_string = {
> +	.length = cpu_to_le16(10),
> +	.chars = {
> +		cpu_to_le16(u'T'),

I've applied this to for-next and intend to keep these there but FYI these 
trigger sparse errors. I don't know if they're fixable or not with 
reasonable effort on kernel side.

$ sparse --version
0.6.4 (Debian: 0.6.4-3)

--
 i.