linux-kernel - Re: [PATCH 2/2] drm/tests: managed: Add a simple test for drmm_managed

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Message-ID: <3sio7356dxi5nbld2eupih3rzazvef4ebusrpdrhabnpg7pns4@5zxfnd4az4li>
Date:   Thu, 30 Nov 2023 09:38:35 +0100
From:   Maxime Ripard <mripard@...nel.org>
To:     Michał Winiarski <michal.winiarski@...el.com>
Cc:     intel-xe@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Michal Wajdeczko <michal.wajdeczko@...el.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Maíra Canal <mcanal@...lia.com>
Subject: Re: [PATCH 2/2] drm/tests: managed: Add a simple test for
 drmm_managed_release

Hi,

Thanks for creating a test for that, that's really appreciated :)

On Wed, Nov 29, 2023 at 11:14:12PM +0100, Michał Winiarski wrote:
> Add a simple test that checks whether the action is indeed called right
> away and that it is not called on the final drm_dev_put().
> 
> Signed-off-by: Michał Winiarski <michal.winiarski@...el.com>
> ---
>  drivers/gpu/drm/tests/drm_managed_test.c | 65 ++++++++++++++++++------
>  1 file changed, 50 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/gpu/drm/tests/drm_managed_test.c b/drivers/gpu/drm/tests/drm_managed_test.c
> index 1652dca11d30c..a645ea42aee56 100644
> --- a/drivers/gpu/drm/tests/drm_managed_test.c
> +++ b/drivers/gpu/drm/tests/drm_managed_test.c
> @@ -12,6 +12,8 @@
>  #define TEST_TIMEOUT_MS	100
>  
>  struct managed_test_priv {
> +	struct drm_device *drm;
> +	struct device *dev;
>  	bool action_done;
>  	wait_queue_head_t action_wq;
>  };
> @@ -26,42 +28,75 @@ static void drm_action(struct drm_device *drm, void *ptr)
>  
>  static void drm_test_managed_run_action(struct kunit *test)
>  {
> -	struct managed_test_priv *priv;
> -	struct drm_device *drm;
> -	struct device *dev;
> +	struct managed_test_priv *priv = test->priv;
>  	int ret;
>  
> -	priv = kunit_kzalloc(test, sizeof(*priv), GFP_KERNEL);
> -	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv);
> -	init_waitqueue_head(&priv->action_wq);
> +	ret = drmm_add_action_or_reset(priv->drm, drm_action, priv);
> +	KUNIT_EXPECT_EQ(test, ret, 0);
>  
> -	dev = drm_kunit_helper_alloc_device(test);
> -	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, dev);
> +	ret = drm_dev_register(priv->drm, 0);
> +	KUNIT_ASSERT_EQ(test, ret, 0);
> +
> +	drm_dev_unregister(priv->drm);
> +	drm_kunit_helper_free_device(test, priv->dev);

I think we'll need two patches here, one to convert to having an init
function, and one to actually add the new test, it's pretty confusing as
it is.

>  
> -	drm = __drm_kunit_helper_alloc_drm_device(test, dev, sizeof(*drm), 0, DRIVER_MODESET);
> -	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, drm);
> +	ret = wait_event_interruptible_timeout(priv->action_wq, priv->action_done,
> +					       msecs_to_jiffies(TEST_TIMEOUT_MS));
> +	KUNIT_EXPECT_GT(test, ret, 0);
> +}
>  
> -	ret = drmm_add_action_or_reset(drm, drm_action, priv);
> +static void drm_test_managed_release_action(struct kunit *test)
> +{
> +	struct managed_test_priv *priv = test->priv;
> +	int ret;
> +
> +	ret = drmm_add_action_or_reset(priv->drm, drm_action, priv);
>  	KUNIT_EXPECT_EQ(test, ret, 0);
>  
> -	ret = drm_dev_register(drm, 0);
> +	ret = drm_dev_register(priv->drm, 0);
>  	KUNIT_ASSERT_EQ(test, ret, 0);
>  
> -	drm_dev_unregister(drm);
> -	drm_kunit_helper_free_device(test, dev);
> +	drmm_release_action(priv->drm, drm_action, priv);
> +	KUNIT_EXPECT_TRUE(test, priv->action_done);
> +	priv->action_done = false;
> +
> +	drm_dev_unregister(priv->drm);
> +	drm_kunit_helper_free_device(test, priv->dev);
>  
>  	ret = wait_event_interruptible_timeout(priv->action_wq, priv->action_done,
>  					       msecs_to_jiffies(TEST_TIMEOUT_MS));
> -	KUNIT_EXPECT_GT(test, ret, 0);
> +	KUNIT_EXPECT_EQ(test, ret, 0);
> +}
> +
> +static int drm_managed_test_init(struct kunit *test)
> +{
> +	struct managed_test_priv *priv;
> +
> +	priv = kunit_kzalloc(test, sizeof(*priv), GFP_KERNEL);
> +	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv);
> +	init_waitqueue_head(&priv->action_wq);

Also, I know that it was there before, but I'm not sure it's valid from
a lifetime point of view. Or at least, we have to think hard enough
about it to just remove that construct

> +	priv->dev = drm_kunit_helper_alloc_device(test);
> +	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv->dev);
> +
> +	priv->drm = __drm_kunit_helper_alloc_drm_device(test, priv->dev, sizeof(*priv->drm),
> +							0, DRIVER_MODESET);
> +	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv->drm);

For example by storing the drm_device struct in the priv structure
directly, and thus everything will just work out.

Maxime

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