greybus: core: return error code when creating endo

Return a pointer-coded error from gb_endo_create() rather than just
a null pointer in the event an error occurs.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/core.c

@@ -177,6 +177,7 @@ struct greybus_host_device *greybus_create_hd(struct greybus_host_driver *driver
 					      size_t buffer_size_max)
 {
 	struct greybus_host_device *hd;
+	struct gb_endo *endo;
 	u16 endo_id = 0x4755; // FIXME - get endo "ID" from the SVC
 
 	/*
@@ -211,11 +212,12 @@ struct greybus_host_device *greybus_create_hd(struct greybus_host_driver *driver
 	ida_init(&hd->cport_id_map);
 	hd->buffer_size_max = buffer_size_max;
 
-	hd->endo = gb_endo_create(hd, endo_id);
-	if (!hd->endo) {
+	endo = gb_endo_create(hd, endo_id);
+	if (IS_ERR(endo)) {
 		greybus_remove_hd(hd);
 		return NULL;
 	}
+	hd->endo = endo;
 
 	return hd;
 }

drivers/staging/greybus/endo.c

@@ -430,16 +430,19 @@ struct gb_endo *gb_endo_create(struct greybus_host_device *hd, u16 endo_id)
 
 	endo = kzalloc(sizeof(*endo), GFP_KERNEL);
 	if (!endo)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	/* First check if the value supplied is a valid endo id */
-	if (gb_endo_validate_id(hd, &endo->layout, endo_id))
+	if (gb_endo_validate_id(hd, &endo->layout, endo_id)) {
+		retval = -EINVAL;
 		goto free_endo;
+	}
 
 	endo->id = endo_id;
 
 	/* Register Endo device */
-	if (gb_endo_register(hd, endo))
+	retval = gb_endo_register(hd, endo);
+	if (retval)
 		goto free_endo;
 
 	/* Create modules/interfaces */
@@ -453,7 +456,8 @@ struct gb_endo *gb_endo_create(struct greybus_host_device *hd, u16 endo_id)
 
 free_endo:
 	kfree(endo);
-	return NULL;
+
+	return ERR_PTR(retval);
 }
 
 void gb_endo_remove(struct gb_endo *endo)