[Intel-xe] [PATCH 2/3] drm/tests/drm_exec: Add a test for object freeing within drm_exec_fini()

[Maxime Ripard]

Hi,

On Tue, Sep 05, 2023 at 10:58:31AM +0200, Thomas Hellström wrote:
> Check that object freeing from within drm_exec_fini() works as expected
> and doesn't generate any warnings.
> 
> Cc: Christian König <christian.koenig at amd.com>
> Cc: dri-devel at lists.freedesktop.org
> Signed-off-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
> ---
>  drivers/gpu/drm/tests/drm_exec_test.c | 47 +++++++++++++++++++++++++++
>  1 file changed, 47 insertions(+)
> 
> diff --git a/drivers/gpu/drm/tests/drm_exec_test.c b/drivers/gpu/drm/tests/drm_exec_test.c
> index 563949d777dd..294c25f49cc7 100644
> --- a/drivers/gpu/drm/tests/drm_exec_test.c
> +++ b/drivers/gpu/drm/tests/drm_exec_test.c
> @@ -170,6 +170,52 @@ static void test_prepare_array(struct kunit *test)
>  	drm_gem_private_object_fini(&gobj2);
>  }
>  
> +static const struct drm_gem_object_funcs put_funcs = {
> +	.free = (void *)kfree,
> +};
> +
> +/*
> + * Check that freeing objects from within drm_exec_fini()
> + * behaves as expected.
> + */
> +static void test_early_put(struct kunit *test)
> +{
> +	struct drm_exec_priv *priv = test->priv;
> +	struct drm_gem_object *gobj1;
> +	struct drm_gem_object *gobj2;
> +	struct drm_gem_object *array[2];
> +	struct drm_exec exec;
> +	int ret;
> +
> +	gobj1 = kzalloc(sizeof(*gobj1), GFP_KERNEL);
> +	KUNIT_EXPECT_NOT_ERR_OR_NULL(test, gobj1);
> +	if (!gobj1)
> +		return;
> +
> +	gobj2 = kzalloc(sizeof(*gobj2), GFP_KERNEL);
> +	KUNIT_EXPECT_NOT_ERR_OR_NULL(test, gobj2);
> +	if (!gobj2) {
> +		kfree(gobj1);
> +		return;
> +	}
> +
> +	gobj1->funcs = &put_funcs;
> +	gobj2->funcs = &put_funcs;
> +	array[0] = gobj1;
> +	array[1] = gobj2;
> +	drm_gem_private_object_init(priv->drm, gobj1, PAGE_SIZE);
> +	drm_gem_private_object_init(priv->drm, gobj2, PAGE_SIZE);
> +
> +	drm_exec_init(&exec, DRM_EXEC_INTERRUPTIBLE_WAIT);
> +	drm_exec_until_all_locked(&exec)
> +		ret = drm_exec_prepare_array(&exec, array, ARRAY_SIZE(array),
> +					     1);
> +	KUNIT_EXPECT_EQ(test, ret, 0);
> +	drm_gem_object_put(gobj1);
> +	drm_gem_object_put(gobj2);
> +	drm_exec_fini(&exec);

It doesn't look like you actually check that "freeing objects from
within drm_exec_fini() behaves as expected." What is the expectation
here, and how is it checked?

Maxime
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