Hi Maxime,

On 18/03/25 11:17, Maxime Ripard wrote:
The vc4-pv-muxing-combinations and vc5-pv-muxing-combinations test
suites use a common test init function which, in part, allocates the
drm atomic state the test will use.

That allocation relies on  drm_kunit_helper_atomic_state_alloc(), and
thus requires a struct drm_modeset_acquire_ctx. This context will then
be stored in the allocated state->acquire_ctx field.

However, the context is local to the test init function, and is cleared
as soon as drm_kunit_helper_atomic_state_alloc() is done. We thus end up
with an dangling pointer to a cleared context in state->acquire_ctx for
our test to consumes.

We should really allocate the context and the state in the test
functions, so we can also control when we're done with it.

Fixes: 30188df0c387 ("drm/tests: Drop drm_kunit_helper_acquire_ctx_alloc()")
Signed-off-by: Maxime Ripard <mrip...@kernel.org>
---
  drivers/gpu/drm/vc4/tests/vc4_test_pv_muxing.c | 41 +++++++++++++++++---------
  1 file changed, 27 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/vc4/tests/vc4_test_pv_muxing.c 
b/drivers/gpu/drm/vc4/tests/vc4_test_pv_muxing.c
index 
992e8f5c5c6ea8d92338a8fe739fa1115ff85338..52c04ef33206bf4f9e21e3c8b7cea932824a67fa
 100644
--- a/drivers/gpu/drm/vc4/tests/vc4_test_pv_muxing.c
+++ b/drivers/gpu/drm/vc4/tests/vc4_test_pv_muxing.c
@@ -18,11 +18,10 @@
#include "vc4_mock.h" struct pv_muxing_priv {
        struct vc4_dev *vc4;
-       struct drm_atomic_state *state;

Can't we add `struct drm_modeset_acquire_ctx` here? Then, we can be sure
that the context exists during the entire test case.

Also, we can add `drm_modeset_drop_locks()` and
`drm_modeset_acquire_fini()` to a exit function in the kunit suite.

Best Regards,
- Maíra

  };
static bool check_fifo_conflict(struct kunit *test,
                                const struct drm_atomic_state *state)
  {
@@ -675,14 +674,23 @@ KUNIT_ARRAY_PARAM(vc5_test_pv_muxing_invalid,
static void drm_vc4_test_pv_muxing(struct kunit *test)
  {
        const struct pv_muxing_param *params = test->param_value;
        const struct pv_muxing_priv *priv = test->priv;
-       struct drm_atomic_state *state = priv->state;
+       struct drm_modeset_acquire_ctx ctx;
+       struct drm_atomic_state *state;
+       struct drm_device *drm;
+       struct vc4_dev *vc4;
        unsigned int i;
        int ret;
+ drm_modeset_acquire_init(&ctx, 0);
+
+       vc4 = priv->vc4;
+       drm = &vc4->base;
+       state = drm_kunit_helper_atomic_state_alloc(test, drm, &ctx);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, state);
        for (i = 0; i < params->nencoders; i++) {
                enum vc4_encoder_type enc_type = params->encoders[i];
ret = vc4_mock_atomic_add_output(test, state, enc_type);
                KUNIT_ASSERT_EQ(test, ret, 0);
@@ -698,56 +706,61 @@ static void drm_vc4_test_pv_muxing(struct kunit *test)
                enum vc4_encoder_type enc_type = params->encoders[i];
KUNIT_EXPECT_TRUE(test, check_channel_for_encoder(test, state, enc_type,
                                                                  
params->check_fn));
        }
+
+       drm_modeset_drop_locks(&ctx);
+       drm_modeset_acquire_fini(&ctx);
  }
static void drm_vc4_test_pv_muxing_invalid(struct kunit *test)
  {
        const struct pv_muxing_param *params = test->param_value;
        const struct pv_muxing_priv *priv = test->priv;
-       struct drm_atomic_state *state = priv->state;
+       struct drm_modeset_acquire_ctx ctx;
+       struct drm_atomic_state *state;
+       struct drm_device *drm;
+       struct vc4_dev *vc4;
        unsigned int i;
        int ret;
+ drm_modeset_acquire_init(&ctx, 0);
+
+       vc4 = priv->vc4;
+       drm = &vc4->base;
+       state = drm_kunit_helper_atomic_state_alloc(test, drm, &ctx);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, state);
+
        for (i = 0; i < params->nencoders; i++) {
                enum vc4_encoder_type enc_type = params->encoders[i];
ret = vc4_mock_atomic_add_output(test, state, enc_type);
                KUNIT_ASSERT_EQ(test, ret, 0);
        }
ret = drm_atomic_check_only(state);
        KUNIT_EXPECT_LT(test, ret, 0);
+
+       drm_modeset_drop_locks(&ctx);
+       drm_modeset_acquire_fini(&ctx);
  }
static int vc4_pv_muxing_test_init(struct kunit *test)
  {
        const struct pv_muxing_param *params = test->param_value;
-       struct drm_modeset_acquire_ctx ctx;
        struct pv_muxing_priv *priv;
-       struct drm_device *drm;
        struct vc4_dev *vc4;
priv = kunit_kzalloc(test, sizeof(*priv), GFP_KERNEL);
        KUNIT_ASSERT_NOT_NULL(test, priv);
        test->priv = priv;
vc4 = params->mock_fn(test);
        KUNIT_ASSERT_NOT_ERR_OR_NULL(test, vc4);
        priv->vc4 = vc4;
- drm_modeset_acquire_init(&ctx, 0);
-
-       drm = &vc4->base;
-       priv->state = drm_kunit_helper_atomic_state_alloc(test, drm, &ctx);
-       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv->state);
-
-       drm_modeset_drop_locks(&ctx);
-       drm_modeset_acquire_fini(&ctx);
-
        return 0;
  }
static struct kunit_case vc4_pv_muxing_tests[] = {
        KUNIT_CASE_PARAM(drm_vc4_test_pv_muxing,


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