drm/i915: Objects on the unbound list may still have an active reference

Due to the lazy retirement semantics, even though we have unbound an
object, it may still hold onto an active reference. So in the debug code,
play safe.

v2: Export i915_gem_shrink() rather than opencoding it.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -3826,7 +3826,6 @@ i915_drop_caches_set(void *data, u64 val)
 {
 	struct drm_device *dev = data;
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	struct drm_i915_gem_object *obj, *next;
 	int ret;
 
 	DRM_DEBUG("Dropping caches: 0x%08llx\n", val);
@@ -3846,36 +3845,11 @@ i915_drop_caches_set(void *data, u64 val)
 	if (val & (DROP_RETIRE | DROP_ACTIVE))
 		i915_gem_retire_requests(dev);
 
-	if (val & DROP_BOUND) {
-		list_for_each_entry_safe(obj, next, &dev_priv->mm.bound_list,
-					 global_list) {
-			struct i915_vma *vma, *v;
+	if (val & DROP_BOUND)
+		i915_gem_shrink(dev_priv, LONG_MAX, I915_SHRINK_BOUND);
 
-			ret = 0;
-			drm_gem_object_reference(&obj->base);
-			list_for_each_entry_safe(vma, v, &obj->vma_list, vma_link) {
-				if (vma->pin_count)
-					continue;
-
-				ret = i915_vma_unbind(vma);
-				if (ret)
-					break;
-			}
-			drm_gem_object_unreference(&obj->base);
-			if (ret)
-				goto unlock;
-		}
-	}
-
-	if (val & DROP_UNBOUND) {
-		list_for_each_entry_safe(obj, next, &dev_priv->mm.unbound_list,
-					 global_list)
-			if (obj->pages_pin_count == 0) {
-				ret = i915_gem_object_put_pages(obj);
-				if (ret)
-					goto unlock;
-			}
-	}
+	if (val & DROP_UNBOUND)
+		i915_gem_shrink(dev_priv, LONG_MAX, I915_SHRINK_UNBOUND);
 
 unlock:
 	mutex_unlock(&dev->struct_mutex);