Re: [Qemu-devel] [PATCH 1/1] virtio-blk: fix race on guest notifiers

[Cornelia Huck <cornelia.huck@de.ibm.com>]

On Thu,  2 Mar 2017 14:04:22 +0100
Halil Pasic <pasic@linux.vnet.ibm.com> wrote:

> diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c
> index 5556f0e..13dd14d 100644
> --- a/hw/block/dataplane/virtio-blk.c
> +++ b/hw/block/dataplane/virtio-blk.c
> @@ -258,9 +258,16 @@ void virtio_blk_data_plane_stop(VirtIODevice *vdev)
>          virtio_queue_aio_set_host_notifier_handler(vq, s->ctx, NULL);
>      }
> 
> -    /* Drain and switch bs back to the QEMU main loop */
> +    /* Drain and switch bs back to the QEMU main loop. After drain, the
> +     * device will not submit (nor comple) any requests until dataplane

s/comple/complete/

> +     * starts again.
> +     */
>      blk_set_aio_context(s->conf->conf.blk, qemu_get_aio_context());
> 
> +    /* Notify guest before the guest notifiers get cleaned up */
> +    qemu_bh_cancel(s->bh);
> +    notify_guest_bh(s);
> +

Hm... does virtio-scsi dataplane need a similar treatment? Or am I
missing something?

>      aio_context_release(s->ctx);
> 
>      for (i = 0; i < nvqs; i++) {