Re: [PATCH v7 4/5] drm: Suppress intentional warning backtraces in scaling unit tests

[David Gow]

Le 20/04/2026 à 8:28 PM, Albert Esteve a écrit :
> From: Guenter Roeck <linux@xxxxxxxxxxxx>
>
> The drm_test_rect_calc_hscale and drm_test_rect_calc_vscale unit tests
> intentionally trigger warning backtraces by providing bad parameters to
> the tested functions. What is tested is the return value, not the existence
> of a warning backtrace. Suppress the backtraces to avoid clogging the
> kernel log and distraction from real problems.
>
> Tested-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>
> Acked-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> Acked-by: Maíra Canal <mcanal@xxxxxxxxxx>
> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> Cc: David Airlie <airlied@xxxxxxxxx>
> Cc: Daniel Vetter <daniel@xxxxxxxx>
> Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> Signed-off-by: Alessandro Carminati <acarmina@xxxxxxxxxx>
> Signed-off-by: Albert Esteve <aesteve@xxxxxxxxxx>
> ---

Acked-by: David Gow <david@xxxxxxxxxxxx>

Some of the suggestions in the thread around __cleanup() et al. sound 
good to me, too. I suspect that it should work given the 
kunit_add_action() / resource system use anyway, so even if an assertion 
fires, things should be cleaned up properly.

Cheers,
-- David

>   drivers/gpu/drm/tests/drm_rect_test.c | 14 ++++++++++++++
>   1 file changed, 14 insertions(+)
>
> diff --git a/drivers/gpu/drm/tests/drm_rect_test.c b/drivers/gpu/drm/tests/drm_rect_test.c
> index 17e1f34b76101..1dd7d819165e7 100644
> --- a/drivers/gpu/drm/tests/drm_rect_test.c
> +++ b/drivers/gpu/drm/tests/drm_rect_test.c
> @@ -409,8 +409,15 @@ static void drm_test_rect_calc_hscale(struct kunit *test)
>   	const struct drm_rect_scale_case *params = test->param_value;
>   	int scaling_factor;
>   
> +	/*
> +	 * drm_rect_calc_hscale() generates a warning backtrace whenever bad
> +	 * parameters are passed to it. This affects all unit tests with an
> +	 * error code in expected_scaling_factor.
> +	 */
> +	KUNIT_START_SUPPRESSED_WARNING(test);
>   	scaling_factor = drm_rect_calc_hscale(&params->src, &params->dst,
>   					      params->min_range, params->max_range);
> +	KUNIT_END_SUPPRESSED_WARNING(test);
>   
>   	KUNIT_EXPECT_EQ(test, scaling_factor, params->expected_scaling_factor);
>   }
> @@ -420,8 +427,15 @@ static void drm_test_rect_calc_vscale(struct kunit *test)
>   	const struct drm_rect_scale_case *params = test->param_value;
>   	int scaling_factor;
>   
> +	/*
> +	 * drm_rect_calc_vscale() generates a warning backtrace whenever bad
> +	 * parameters are passed to it. This affects all unit tests with an
> +	 * error code in expected_scaling_factor.
> +	 */
> +	KUNIT_START_SUPPRESSED_WARNING(test);
>   	scaling_factor = drm_rect_calc_vscale(&params->src, &params->dst,
>   					      params->min_range, params->max_range);
> +	KUNIT_END_SUPPRESSED_WARNING(test);
>   
>   	KUNIT_EXPECT_EQ(test, scaling_factor, params->expected_scaling_factor);
>   }