virtio-mem: mark device ready before registering callbacks in kdump mode

After the callbacks are registered we may immediately get a callback. So
mark the device ready before registering the callbacks.

Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20241204125444.1734652-10-david@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Author: davidhildenbrand

drivers/virtio/virtio_mem.c

@@ -2648,6 +2648,7 @@ static int virtio_mem_init_hotplug(struct virtio_mem *vm)
 	if (rc)
 		goto out_unreg_pm;
 
+	virtio_device_ready(vm->vdev);
 	return 0;
 out_unreg_pm:
 	unregister_pm_notifier(&vm->pm_notifier);
@@ -2729,6 +2730,8 @@ static bool virtio_mem_vmcore_pfn_is_ram(struct vmcore_cb *cb,
 
 static int virtio_mem_init_kdump(struct virtio_mem *vm)
 {
+	/* We must be prepared to receive a callback immediately. */
+	virtio_device_ready(vm->vdev);
 #ifdef CONFIG_PROC_VMCORE
 	dev_info(&vm->vdev->dev, "memory hot(un)plug disabled in kdump kernel\n");
 	vm->vmcore_cb.pfn_is_ram = virtio_mem_vmcore_pfn_is_ram;
@@ -2870,8 +2873,6 @@ static int virtio_mem_probe(struct virtio_device *vdev)
 	if (rc)
 		goto out_del_vq;
 
-	virtio_device_ready(vdev);
-
 	/* trigger a config update to start processing the requested_size */
 	if (!vm->in_kdump) {
 		atomic_set(&vm->config_changed, 1);