drm/tests: modes: Fix drm_display_mode memory leak

drm_analog_tv_mode() and its variants return a drm_display_mode that
needs to be destroyed later one. The drm_modes_analog_tv tests never
do however, which leads to a memory leak.

Let's make sure it's freed.

Reported-by: Philipp Stanner <phasta@mailbox.org>
Closes: https://lore.kernel.org/dri-devel/a7655158a6367ac46194d57f4b7433ef0772a73e.camel@mailbox.org/
Fixes: 4fcd238 ("drm/modes: Add a function to generate analog display modes")
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://lore.kernel.org/r/20250408-drm-kunit-drm-display-mode-memleak-v1-5-996305a2e75a@kernel.org
Signed-off-by: Maxime Ripard <mripard@kernel.org>

Author: mripard

drivers/gpu/drm/tests/drm_modes_test.c

@@ -40,13 +40,17 @@ static void drm_test_modes_analog_tv_ntsc_480i(struct kunit *test)
 {
 	struct drm_test_modes_priv *priv = test->priv;
 	struct drm_display_mode *mode;
+	int ret;
 
 	mode = drm_analog_tv_mode(priv->drm,
 				  DRM_MODE_TV_MODE_NTSC,
 				  13500 * HZ_PER_KHZ, 720, 480,
 				  true);
 	KUNIT_ASSERT_NOT_NULL(test, mode);
 
+	ret = drm_kunit_add_mode_destroy_action(test, mode);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
 	KUNIT_EXPECT_EQ(test, drm_mode_vrefresh(mode), 60);
 	KUNIT_EXPECT_EQ(test, mode->hdisplay, 720);
 
@@ -70,30 +74,41 @@ static void drm_test_modes_analog_tv_ntsc_480i_inlined(struct kunit *test)
 {
 	struct drm_test_modes_priv *priv = test->priv;
 	struct drm_display_mode *expected, *mode;
+	int ret;
 
 	expected = drm_analog_tv_mode(priv->drm,
 				      DRM_MODE_TV_MODE_NTSC,
 				      13500 * HZ_PER_KHZ, 720, 480,
 				      true);
 	KUNIT_ASSERT_NOT_NULL(test, expected);
 
+	ret = drm_kunit_add_mode_destroy_action(test, expected);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
 	mode = drm_mode_analog_ntsc_480i(priv->drm);
 	KUNIT_ASSERT_NOT_NULL(test, mode);
 
+	ret = drm_kunit_add_mode_destroy_action(test, mode);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
 	KUNIT_EXPECT_TRUE(test, drm_mode_equal(expected, mode));
 }
 
 static void drm_test_modes_analog_tv_pal_576i(struct kunit *test)
 {
 	struct drm_test_modes_priv *priv = test->priv;
 	struct drm_display_mode *mode;
+	int ret;
 
 	mode = drm_analog_tv_mode(priv->drm,
 				  DRM_MODE_TV_MODE_PAL,
 				  13500 * HZ_PER_KHZ, 720, 576,
 				  true);
 	KUNIT_ASSERT_NOT_NULL(test, mode);
 
+	ret = drm_kunit_add_mode_destroy_action(test, mode);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
 	KUNIT_EXPECT_EQ(test, drm_mode_vrefresh(mode), 50);
 	KUNIT_EXPECT_EQ(test, mode->hdisplay, 720);
 
@@ -117,16 +132,23 @@ static void drm_test_modes_analog_tv_pal_576i_inlined(struct kunit *test)
 {
 	struct drm_test_modes_priv *priv = test->priv;
 	struct drm_display_mode *expected, *mode;
+	int ret;
 
 	expected = drm_analog_tv_mode(priv->drm,
 				      DRM_MODE_TV_MODE_PAL,
 				      13500 * HZ_PER_KHZ, 720, 576,
 				      true);
 	KUNIT_ASSERT_NOT_NULL(test, expected);
 
+	ret = drm_kunit_add_mode_destroy_action(test, expected);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
 	mode = drm_mode_analog_pal_576i(priv->drm);
 	KUNIT_ASSERT_NOT_NULL(test, mode);
 
+	ret = drm_kunit_add_mode_destroy_action(test, mode);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
 	KUNIT_EXPECT_TRUE(test, drm_mode_equal(expected, mode));
 }