nvme: add uevent variables for controller devices

When we send uevents to userspace, add controller specific
environment variables to uniquly identify the controller beyond
its device name.

This will be useful to address discovery log change events by
actually verifying that the discovery controller is indeed the
same as the device that generated the event.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>

drivers/nvme/host/core.c

@@ -3635,6 +3635,33 @@ void nvme_remove_namespaces(struct nvme_ctrl *ctrl)
 }
 EXPORT_SYMBOL_GPL(nvme_remove_namespaces);
 
+static int nvme_class_uevent(struct device *dev, struct kobj_uevent_env *env)
+{
+	struct nvme_ctrl *ctrl =
+		container_of(dev, struct nvme_ctrl, ctrl_device);
+	struct nvmf_ctrl_options *opts = ctrl->opts;
+	int ret;
+
+	ret = add_uevent_var(env, "NVME_TRTYPE=%s", ctrl->ops->name);
+	if (ret)
+		return ret;
+
+	if (opts) {
+		ret = add_uevent_var(env, "NVME_TRADDR=%s", opts->traddr);
+		if (ret)
+			return ret;
+
+		ret = add_uevent_var(env, "NVME_TRSVCID=%s",
+				opts->trsvcid ?: "none");
+		if (ret)
+			return ret;
+
+		ret = add_uevent_var(env, "NVME_HOST_TRADDR=%s",
+				opts->host_traddr ?: "none");
+	}
+	return ret;
+}
+
 static void nvme_aen_uevent(struct nvme_ctrl *ctrl)
 {
 	char *envp[2] = { NULL, NULL };
@@ -4073,6 +4100,7 @@ static int __init nvme_core_init(void)
 		result = PTR_ERR(nvme_class);
 		goto unregister_chrdev;
 	}
+	nvme_class->dev_uevent = nvme_class_uevent;
 
 	nvme_subsys_class = class_create(THIS_MODULE, "nvme-subsystem");
 	if (IS_ERR(nvme_subsys_class)) {