Hi experts, With latest QEMU (8.2.90), we find two vhost-user-blk backend reconnect failure scenarios: 1. Disconnect vhost-user-blk backend before guest driver probe vblk device, then reconnect backend after guest driver probe device. QEMU won't send out any vhost messages to restore backend. This is because vhost->vdev is NULL before guest driver probe vblk device, so vhost_user_blk_disconnect won't be called, s->connected is still true. Next vhost_user_blk_connect will simply return without doing anything.
2. modprobe -r virtio-blk inside VM, then disconnect backend, then reconnect backend, then modprobe virtio-blk. QEMU won't send messages in vhost_dev_init. This is because rmmod will let qemu call vhost_user_blk_stop, vhost->vdev also become NULL(in vhost_dev_stop), vhost_user_blk_disconnect won't be called. Again s->connected is still true, even chr connect is closed. I think even vhost->vdev is NULL, vhost_user_blk_disconnect should be called when chr connect close? Hope we can have a fix soon. Thanks, Yajun
