vhost: Fix kthread worker cgroup failure handling

If we fail to attach to a cgroup we are leaking the id. This adds
a new goto to free the id.

Fixes: 7d9896e ("vhost: Reintroduce kthread API and add mode selection")
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20251101194358.13605-1-michael.christie@oracle.com>

Author: mikechristie

drivers/vhost/vhost.c

@@ -804,11 +804,13 @@ static int vhost_kthread_worker_create(struct vhost_worker *worker,
 
 	ret = vhost_attach_task_to_cgroups(worker);
 	if (ret)
-		goto stop_worker;
+		goto free_id;
 
 	worker->id = id;
 	return 0;
 
+free_id:
+	xa_erase(&dev->worker_xa, id);
 stop_worker:
 	vhost_kthread_do_stop(worker);
 	return ret;