Check that object freeing from within drm_exec_fini() works as expected
and is unlikely to generate any warnings.
v3:
- Condition the test on CONFIG_DEBUG_LOCK_ALLOC
- Make the test fail if the situation that generates the lockdep
warning occurs. (Maxime Ripard)
Cc: Maxime Ripard <mripard@xxxxxxxxxx>
Cc: Christian König <christian.koenig@xxxxxxx>
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/tests/drm_exec_test.c | 82 +++++++++++++++++++++++++++
1 file changed, 82 insertions(+)
diff --git a/drivers/gpu/drm/tests/drm_exec_test.c b/drivers/gpu/drm/tests/drm_exec_test.c
index 563949d777dd..83fddc6fe1ae 100644
--- a/drivers/gpu/drm/tests/drm_exec_test.c
+++ b/drivers/gpu/drm/tests/drm_exec_test.c
@@ -21,6 +21,9 @@
struct drm_exec_priv {
struct device *dev;
struct drm_device *drm;
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+ struct drm_exec *exec;
+#endif
};
static int drm_exec_test_init(struct kunit *test)
@@ -170,6 +173,82 @@ static void test_prepare_array(struct kunit *test)
drm_gem_private_object_fini(&gobj2);
}
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+static void drm_exec_test_obj_free(struct drm_gem_object *gem)
+{
+ struct kunit *test = current->kunit_test;
+ struct drm_exec_priv *priv = test->priv;
+ bool resv_class_held;
+ bool first_object_locked;
+
+ /*
+ * The lock alloc tracking code may warn if the dma_resv lock
+ * class is still held, and we're freeing the first object we
+ * locked.
+ */
+ resv_class_held = (lockdep_is_held(&gem->resv->lock.base) ==
+ LOCK_STATE_HELD);
+ first_object_locked = (gem == priv->exec->objects[0]);
+ KUNIT_EXPECT_FALSE(current->kunit_test,
+ resv_class_held && first_object_locked);
+
+ dma_resv_fini(gem->resv);
+ kfree(gem);
+}
+
+static const struct drm_gem_object_funcs put_funcs = {
+ .free = drm_exec_test_obj_free,
+};
+
+/*
+ * Check that freeing objects from within drm_exec_fini()
+ * doesn't trigger a false lock alloc warning due to
+ * the dma_resv lock *class* still being held and we're
+ * freeing the first object locked, which *might* be
+ * registered as the address of the held lock of that
+ * lock class.
+ */
+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;
+
+ priv->exec = &exec;
+
+ gobj1 = kzalloc(sizeof(*gobj1), GFP_KERNEL);
+ KUNIT_EXPECT_NOT_NULL(test, gobj1);
+ if (!gobj1)
+ return;
+
+ gobj2 = kzalloc(sizeof(*gobj2), GFP_KERNEL);
+ KUNIT_EXPECT_NOT_NULL(test, gobj2);
+ if (!gobj2) {
+ kfree(gobj1);
+ return;
+ }
+
+ gobj1->funcs = &put_funcs;
+ gobj2->funcs = &put_funcs;
+ drm_gem_private_object_init(priv->drm, gobj1, PAGE_SIZE);
+ drm_gem_private_object_init(priv->drm, gobj2, PAGE_SIZE);
+ array[0] = gobj1;
+ array[1] = gobj2;
+
+ 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);
+}
+#endif
+
static void test_multiple_loops(struct kunit *test)
{
struct drm_exec exec;
@@ -198,6 +277,9 @@ static struct kunit_case drm_exec_tests[] = {
KUNIT_CASE(test_prepare),
KUNIT_CASE(test_prepare_array),
KUNIT_CASE(test_multiple_loops),
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+ KUNIT_CASE(test_early_put),
+#endif
{}
};
--
2.41.0
