drm/i915: Handle drm-layer errors in intel_dp_add_mst_connector

Make intel_dp_add_mst_connector handle error returns from the drm_ calls.
Add intel_connector_free to support cleanup on the error path.

v2: Rename new function to avoid confusion, and simplify error
paths (Ville)

v3: Indentation fixup, style fixes (Ville)

v4: Clarify usage of intel_connector_free, and fix usage of
intel_connector_free

v5: Rebase

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: James Ausmus <james.ausmus@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171013180144.15865-1-james.ausmus@intel.com

drivers/gpu/drm/i915/intel_display.c

@@ -6139,6 +6139,19 @@ struct intel_connector *intel_connector_alloc(void)
 	return connector;
 }
 
+/*
+ * Free the bits allocated by intel_connector_alloc.
+ * This should only be used after intel_connector_alloc has returned
+ * successfully, and before drm_connector_init returns successfully.
+ * Otherwise the destroy callbacks for the connector and the state should
+ * take care of proper cleanup/free
+ */
+void intel_connector_free(struct intel_connector *connector)
+{
+	kfree(to_intel_digital_connector_state(connector->base.state));
+	kfree(connector);
+}
+
 /* Simple connector->get_hw_state implementation for encoders that support only
  * one connector and no cloning and hence the encoder state determines the state
  * of the connector. */

drivers/gpu/drm/i915/intel_dp_mst.c

@@ -458,13 +458,20 @@ static struct drm_connector *intel_dp_add_mst_connector(struct drm_dp_mst_topolo
 	struct intel_connector *intel_connector;
 	struct drm_connector *connector;
 	enum pipe pipe;
+	int ret;
 
 	intel_connector = intel_connector_alloc();
 	if (!intel_connector)
 		return NULL;
 
 	connector = &intel_connector->base;
-	drm_connector_init(dev, connector, &intel_dp_mst_connector_funcs, DRM_MODE_CONNECTOR_DisplayPort);
+	ret = drm_connector_init(dev, connector, &intel_dp_mst_connector_funcs,
+				 DRM_MODE_CONNECTOR_DisplayPort);
+	if (ret) {
+		intel_connector_free(intel_connector);
+		return NULL;
+	}
+
 	drm_connector_helper_add(connector, &intel_dp_mst_connector_helper_funcs);
 
 	intel_connector->get_hw_state = intel_dp_mst_get_hw_state;
@@ -472,15 +479,27 @@ static struct drm_connector *intel_dp_add_mst_connector(struct drm_dp_mst_topolo
 	intel_connector->port = port;
 
 	for_each_pipe(dev_priv, pipe) {
-		drm_mode_connector_attach_encoder(&intel_connector->base,
-						  &intel_dp->mst_encoders[pipe]->base.base);
+		struct drm_encoder *enc =
+			&intel_dp->mst_encoders[pipe]->base.base;
+
+		ret = drm_mode_connector_attach_encoder(&intel_connector->base,
+							enc);
+		if (ret)
+			goto err;
 	}
 
 	drm_object_attach_property(&connector->base, dev->mode_config.path_property, 0);
 	drm_object_attach_property(&connector->base, dev->mode_config.tile_property, 0);
 
-	drm_mode_connector_set_path_property(connector, pathprop);
+	ret = drm_mode_connector_set_path_property(connector, pathprop);
+	if (ret)
+		goto err;
+
 	return connector;
+
+err:
+	drm_connector_cleanup(connector);
+	return NULL;
 }
 
 static void intel_dp_register_mst_connector(struct drm_connector *connector)

drivers/gpu/drm/i915/intel_drv.h

@@ -1363,6 +1363,7 @@ void intel_pps_unlock_regs_wa(struct drm_i915_private *dev_priv);
 void intel_encoder_destroy(struct drm_encoder *encoder);
 int intel_connector_init(struct intel_connector *);
 struct intel_connector *intel_connector_alloc(void);
+void intel_connector_free(struct intel_connector *connector);
 bool intel_connector_get_hw_state(struct intel_connector *connector);
 void intel_connector_attach_encoder(struct intel_connector *connector,
 				    struct intel_encoder *encoder);