Re: [PATCH v2 3/3] drivers: base: test: Add ...find_device_by...(... NULL) tests

[Maxime Ripard <mripard@kernel.org>]

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Hi,

On Wed, Dec 11, 2024 at 04:31:41PM -0800, Brian Norris wrote:
> We recently updated these device_match*() (and therefore, various
> *find_device_by*()) functions to return a consistent 'false' value when
> trying to match a NULL handle. Add tests for this.
> 
> This provides regression-testing coverage for the sorts of bugs that
> underly commit 5c8418cf4025 ("PCI/pwrctrl: Unregister platform device
> only if one actually exists").
> 
> Signed-off-by: Brian Norris <briannorris@chromium.org>
> ---
> 
> Changes in v2:
>  * Keep "devm" and "match" tests in separate suites
> 
>  drivers/base/test/platform-device-test.c | 42 +++++++++++++++++++++++-
>  1 file changed, 41 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/base/test/platform-device-test.c b/drivers/base/test/platform-device-test.c
> index ea05b8785743..c8d4b0a385f2 100644
> --- a/drivers/base/test/platform-device-test.c
> +++ b/drivers/base/test/platform-device-test.c
> @@ -3,6 +3,8 @@
>  #include <kunit/resource.h>
>  
>  #include <linux/device.h>
> +#include <linux/device/bus.h>
> +#include <linux/of_platform.h>
>  #include <linux/platform_device.h>
>  
>  #define DEVICE_NAME "test"
> @@ -217,7 +219,45 @@ static struct kunit_suite platform_device_devm_test_suite = {
>  	.test_cases = platform_device_devm_tests,
>  };
>  
> -kunit_test_suite(platform_device_devm_test_suite);
> +static void platform_device_find_by_null_test(struct kunit *test)
> +{
> +	struct platform_device *pdev;
> +	int ret;
> +
> +	pdev = platform_device_alloc(DEVICE_NAME, PLATFORM_DEVID_NONE);
> +	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, pdev);
> +
> +	ret = platform_device_add(pdev);
> +	KUNIT_ASSERT_EQ(test, ret, 0);

I *think* you have a bug there: if platform_device_add fails,
KUNIT_ASSERT will stop the test execution and thus you will leak the
platform_device you just allocated.

You need to call platform_device_put in such a case, but if
platform_device_add succeeds then you need to call
platform_device_unregister instead.

It would be better to use kunit_platform_device_alloc and
kunit_platform_device_add that already deal with this.

The rest looks good to me, once fixed:
Reviewed-by: Maxime Ripard <mripard@kernel.org>

Maxime

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