drm/modes: add connector reference counting. (v2)

This uses the previous changes to add reference counts
to drm connector objects.

v2: move fbdev changes to their own patch.
add some kerneldoc

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_atomic.c

@@ -156,6 +156,7 @@ void drm_atomic_state_default_clear(struct drm_atomic_state *state)
 						       state->connector_states[i]);
 		state->connectors[i] = NULL;
 		state->connector_states[i] = NULL;
+		drm_connector_unreference(connector);
 	}
 
 	for (i = 0; i < config->num_crtc; i++) {
@@ -932,6 +933,7 @@ drm_atomic_get_connector_state(struct drm_atomic_state *state,
 	if (!connector_state)
 		return ERR_PTR(-ENOMEM);
 
+	drm_connector_reference(connector);
 	state->connector_states[index] = connector_state;
 	state->connectors[index] = connector;
 	connector_state->state = state;
@@ -1622,12 +1624,19 @@ retry:
 		}
 
 		obj = drm_mode_object_find(dev, obj_id, DRM_MODE_OBJECT_ANY);
-		if (!obj || !obj->properties) {
+		if (!obj) {
+			ret = -ENOENT;
+			goto out;
+		}
+
+		if (!obj->properties) {
+			drm_mode_object_unreference(obj);
 			ret = -ENOENT;
 			goto out;
 		}
 
 		if (get_user(count_props, count_props_ptr + copied_objs)) {
+			drm_mode_object_unreference(obj);
 			ret = -EFAULT;
 			goto out;
 		}
@@ -1640,12 +1649,14 @@ retry:
 			struct drm_property *prop;
 
 			if (get_user(prop_id, props_ptr + copied_props)) {
+				drm_mode_object_unreference(obj);
 				ret = -EFAULT;
 				goto out;
 			}
 
 			prop = drm_property_find(dev, prop_id);
 			if (!prop) {
+				drm_mode_object_unreference(obj);
 				ret = -ENOENT;
 				goto out;
 			}
@@ -1653,13 +1664,16 @@ retry:
 			if (copy_from_user(&prop_value,
 					   prop_values_ptr + copied_props,
 					   sizeof(prop_value))) {
+				drm_mode_object_unreference(obj);
 				ret = -EFAULT;
 				goto out;
 			}
 
 			ret = atomic_set_prop(state, obj, prop, prop_value);
-			if (ret)
+			if (ret) {
+				drm_mode_object_unreference(obj);
 				goto out;
+			}
 
 			copied_props++;
 		}
@@ -1670,6 +1684,7 @@ retry:
 			plane_mask |= (1 << drm_plane_index(plane));
 			plane->old_fb = plane->fb;
 		}
+		drm_mode_object_unreference(obj);
 	}
 
 	if (arg->flags & DRM_MODE_PAGE_FLIP_EVENT) {

drivers/gpu/drm/drm_crtc.c

@@ -864,6 +864,16 @@ static void drm_connector_get_cmdline_mode(struct drm_connector *connector)
 		      mode->interlace ?  " interlaced" : "");
 }
 
+static void drm_connector_free(struct kref *kref)
+{
+	struct drm_connector *connector =
+		container_of(kref, struct drm_connector, base.refcount);
+	struct drm_device *dev = connector->dev;
+
+	drm_mode_object_unregister(dev, &connector->base);
+	connector->funcs->destroy(connector);
+}
+
 /**
  * drm_connector_init - Init a preallocated connector
  * @dev: DRM device
@@ -889,7 +899,9 @@ int drm_connector_init(struct drm_device *dev,
 
 	drm_modeset_lock_all(dev);
 
-	ret = drm_mode_object_get_reg(dev, &connector->base, DRM_MODE_OBJECT_CONNECTOR, false, NULL);
+	ret = drm_mode_object_get_reg(dev, &connector->base,
+				      DRM_MODE_OBJECT_CONNECTOR,
+				      false, drm_connector_free);
 	if (ret)
 		goto out_unlock;
 
@@ -2137,7 +2149,7 @@ int drm_mode_getconnector(struct drm_device *dev, void *data,
 
 	mutex_lock(&dev->mode_config.mutex);
 
-	connector = drm_connector_find(dev, out_resp->connector_id);
+	connector = drm_connector_lookup(dev, out_resp->connector_id);
 	if (!connector) {
 		ret = -ENOENT;
 		goto out_unlock;
@@ -2221,6 +2233,7 @@ int drm_mode_getconnector(struct drm_device *dev, void *data,
 out:
 	drm_modeset_unlock(&dev->mode_config.connection_mutex);
 
+	drm_connector_unreference(connector);
 out_unlock:
 	mutex_unlock(&dev->mode_config.mutex);
 
@@ -2865,13 +2878,14 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data,
 		}
 
 		for (i = 0; i < crtc_req->count_connectors; i++) {
+			connector_set[i] = NULL;
 			set_connectors_ptr = (uint32_t __user *)(unsigned long)crtc_req->set_connectors_ptr;
 			if (get_user(out_id, &set_connectors_ptr[i])) {
 				ret = -EFAULT;
 				goto out;
 			}
 
-			connector = drm_connector_find(dev, out_id);
+			connector = drm_connector_lookup(dev, out_id);
 			if (!connector) {
 				DRM_DEBUG_KMS("Connector id %d unknown\n",
 						out_id);
@@ -2899,6 +2913,12 @@ out:
 	if (fb)
 		drm_framebuffer_unreference(fb);
 
+	if (connector_set) {
+		for (i = 0; i < crtc_req->count_connectors; i++) {
+			if (connector_set[i])
+				drm_connector_unreference(connector_set[i]);
+		}
+	}
 	kfree(connector_set);
 	drm_mode_destroy(dev, mode);
 	drm_modeset_unlock_all(dev);
@@ -4989,7 +5009,7 @@ int drm_mode_obj_set_property_ioctl(struct drm_device *dev, void *data,
 	property = obj_to_property(prop_obj);
 
 	if (!drm_property_change_valid_get(property, arg->value, &ref))
-		goto out;
+		goto out_unref;
 
 	switch (arg_obj->type) {
 	case DRM_MODE_OBJECT_CONNECTOR:

include/drm/drm_crtc.h

@@ -2571,7 +2571,15 @@ static inline struct drm_encoder *drm_encoder_find(struct drm_device *dev,
 	return mo ? obj_to_encoder(mo) : NULL;
 }
 
-static inline struct drm_connector *drm_connector_find(struct drm_device *dev,
+/**
+ * drm_connector_lookup - lookup connector object
+ * @dev: DRM device
+ * @id: connector object id
+ *
+ * This function looks up the connector object specified by id
+ * add takes a reference to it.
+ */
+static inline struct drm_connector *drm_connector_lookup(struct drm_device *dev,
 		uint32_t id)
 {
 	struct drm_mode_object *mo;
@@ -2639,6 +2647,28 @@ static inline uint32_t drm_framebuffer_read_refcount(struct drm_framebuffer *fb)
 	return atomic_read(&fb->base.refcount.refcount);
 }
 
+/**
+ * drm_connector_reference - incr the connector refcnt
+ * @connector: connector
+ *
+ * This function increments the connector's refcount.
+ */
+static inline void drm_connector_reference(struct drm_connector *connector)
+{
+	drm_mode_object_reference(&connector->base);
+}
+
+/**
+ * drm_connector_unreference - unref a connector
+ * @connector: connector to unref
+ *
+ * This function decrements the connector's refcount and frees it if it drops to zero.
+ */
+static inline void drm_connector_unreference(struct drm_connector *connector)
+{
+	drm_mode_object_unreference(&connector->base);
+}
+
 /* Plane list iterator for legacy (overlay only) planes. */
 #define drm_for_each_legacy_plane(plane, dev) \
 	list_for_each_entry(plane, &(dev)->mode_config.plane_list, head) \