staging: vchiq: Introduce vchiq_validate_params()

When adding a new service validate the configuration parameters
provided, and remove unnecessary checks in vchi, now that we have
validated service's config.
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Link: https://lore.kernel.org/r/20200629150945.10720-23-nsaenzjulienne@suse.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c

@@ -2265,6 +2265,16 @@ vchiq_init_state(struct vchiq_state *state, struct vchiq_slot_zero *slot_zero)
 	return VCHIQ_ERROR;
 }
 
+static int vchiq_validate_params(const struct vchiq_service_params *params)
+{
+	if (!params->callback || !params->fourcc) {
+		vchiq_loud_error("Can't add service, invalid params\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 /* Called from application thread when a client or server service is created. */
 struct vchiq_service *
 vchiq_add_service_internal(struct vchiq_state *state,
@@ -2275,8 +2285,13 @@ vchiq_add_service_internal(struct vchiq_state *state,
 	struct vchiq_service *service;
 	struct vchiq_service __rcu **pservice = NULL;
 	struct vchiq_service_quota *service_quota;
+	int ret;
 	int i;
 
+	ret = vchiq_validate_params(params);
+	if (ret)
+		return NULL;
+
 	service = kmalloc(sizeof(*service), GFP_KERNEL);
 	if (!service)
 		return service;

drivers/staging/vc04_services/interface/vchiq_arm/vchiq_shim.c

@@ -271,15 +271,11 @@ static enum vchiq_status shim_callback(enum vchiq_reason reason,
 	struct vchi_service *service =
 		(struct vchi_service *)VCHIQ_GET_SERVICE_USERDATA(handle);
 
-	if (!service->callback)
-		goto release;
-
 	if (reason == VCHIQ_MESSAGE_AVAILABLE)
 		vchiu_queue_push(&service->queue, header);
 
 	service->callback(service->callback_param, reason, bulk_user);
 
-release:
 	return VCHIQ_SUCCESS;
 }