drm/i915/ttm: Drop region reference counting

There is an interesting refcounting loop:
struct intel_memory_region has a struct ttm_resource_manager,
ttm_resource_manager->move may hold a reference to i915_request,
i915_request may hold a reference to intel_context,
intel_context may hold a reference to drm_i915_gem_object,
drm_i915_gem_object may hold a reference to intel_memory_region.

Break this loop by dropping region reference counting.

In addition, Have regions with a manager moving fence make sure
that all region objects are released before freeing the region.

v6:
- Fix a code comment.

Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211122214554.371864-4-thomas.hellstrom@linux.intel.com

2 files changed, 9 insertions, 6 deletions

diff --git a/drivers/gpu/drm/i915/selftests/intel_memory_region.c b/drivers/gpu/drm/i915/selftests/intel_memory_region.c
index 418caae84759..0d5df0dc7212 100644
--- a/drivers/gpu/drm/i915/selftests/intel_memory_region.c
+++ b/drivers/gpu/drm/i915/selftests/intel_memory_region.c
@@ -225,7 +225,7 @@ static int igt_mock_reserve(void *arg)
 
 out_close:
 	close_objects(mem, &objects);
-	intel_memory_region_put(mem);
+	intel_memory_region_destroy(mem);
 out_free_order:
 	kfree(order);
 	return err;
@@ -439,7 +439,7 @@ static int igt_mock_splintered_region(void *arg)
 out_close:
 	close_objects(mem, &objects);
 out_put:
-	intel_memory_region_put(mem);
+	intel_memory_region_destroy(mem);
 	return err;
 }
 
@@ -507,7 +507,7 @@ static int igt_mock_max_segment(void *arg)
 out_close:
 	close_objects(mem, &objects);
 out_put:
-	intel_memory_region_put(mem);
+	intel_memory_region_destroy(mem);
 	return err;
 }
 
@@ -1196,7 +1196,7 @@ int intel_memory_region_mock_selftests(void)
 
 	err = i915_subtests(tests, mem);
 
-	intel_memory_region_put(mem);
+	intel_memory_region_destroy(mem);
 out_unref:
 	mock_destroy_device(i915);
 	return err;
diff --git a/drivers/gpu/drm/i915/selftests/mock_region.c b/drivers/gpu/drm/i915/selftests/mock_region.c
index 7ec5037eaa58..19bff8afcaaa 100644
--- a/drivers/gpu/drm/i915/selftests/mock_region.c
+++ b/drivers/gpu/drm/i915/selftests/mock_region.c
@@ -84,13 +84,16 @@ static int mock_object_init(struct intel_memory_region *mem,
 	return 0;
 }
 
-static void mock_region_fini(struct intel_memory_region *mem)
+static int mock_region_fini(struct intel_memory_region *mem)
 {
 	struct drm_i915_private *i915 = mem->i915;
 	int instance = mem->instance;
+	int ret;
 
-	intel_region_ttm_fini(mem);
+	ret = intel_region_ttm_fini(mem);
 	ida_free(&i915->selftest.mock_region_instances, instance);
+
+	return ret;
 }
 
 static const struct intel_memory_region_ops mock_region_ops = {