nvme: make nvmf_register_transport require a create_ctrl callback

nvmf_create_ctrl() relys on the presence of a create_crtl callback in the
registered nvmf_transport_ops, so make nvmf_register_transport require one.

Update the available call-sites as well to reflect these changes.
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/nvme/host/fabrics.c

@@ -480,11 +480,16 @@ EXPORT_SYMBOL_GPL(nvmf_connect_io_queue);
  * being implemented to the common NVMe fabrics library. Part of
  * the overall init sequence of starting up a fabrics driver.
  */
-void nvmf_register_transport(struct nvmf_transport_ops *ops)
+int nvmf_register_transport(struct nvmf_transport_ops *ops)
 {
+	if (!ops->create_ctrl)
+		return -EINVAL;
+
 	mutex_lock(&nvmf_transports_mutex);
 	list_add_tail(&ops->entry, &nvmf_transports);
 	mutex_unlock(&nvmf_transports_mutex);
+
+	return 0;
 }
 EXPORT_SYMBOL_GPL(nvmf_register_transport);
 

drivers/nvme/host/fabrics.h

@@ -128,7 +128,7 @@ int nvmf_reg_read64(struct nvme_ctrl *ctrl, u32 off, u64 *val);
 int nvmf_reg_write32(struct nvme_ctrl *ctrl, u32 off, u32 val);
 int nvmf_connect_admin_queue(struct nvme_ctrl *ctrl);
 int nvmf_connect_io_queue(struct nvme_ctrl *ctrl, u16 qid);
-void nvmf_register_transport(struct nvmf_transport_ops *ops);
+int nvmf_register_transport(struct nvmf_transport_ops *ops);
 void nvmf_unregister_transport(struct nvmf_transport_ops *ops);
 void nvmf_free_options(struct nvmf_ctrl_options *opts);
 const char *nvmf_get_subsysnqn(struct nvme_ctrl *ctrl);

drivers/nvme/host/fc.c

@@ -2562,8 +2562,7 @@ static int __init nvme_fc_init_module(void)
 	if (!nvme_fc_wq)
 		return -ENOMEM;
 
-	nvmf_register_transport(&nvme_fc_transport);
-	return 0;
+	return nvmf_register_transport(&nvme_fc_transport);
 }
 
 static void __exit nvme_fc_exit_module(void)

drivers/nvme/host/rdma.c

@@ -2063,8 +2063,7 @@ static int __init nvme_rdma_init_module(void)
 		return ret;
 	}
 
-	nvmf_register_transport(&nvme_rdma_transport);
-	return 0;
+	return nvmf_register_transport(&nvme_rdma_transport);
 }
 
 static void __exit nvme_rdma_cleanup_module(void)

drivers/nvme/target/loop.c

@@ -724,8 +724,7 @@ static int __init nvme_loop_init_module(void)
 	ret = nvmet_register_transport(&nvme_loop_ops);
 	if (ret)
 		return ret;
-	nvmf_register_transport(&nvme_loop_transport);
-	return 0;
+	return nvmf_register_transport(&nvme_loop_transport);
 }
 
 static void __exit nvme_loop_cleanup_module(void)