Re: [Qemu-devel] [PATCH 7/9] virtio-scsi: use aio handler for data plane

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

On Wed, 30 Mar 2016 14:48:06 +0200
Paolo Bonzini <pbonzini@redhat.com> wrote:

> In addition to handling IO in vcpu thread and in io thread, dataplane
> introduces yet another mode: handling it by aio.
> 
> This reuses the same handler as previous modes, which triggers races as
> these were not designed to be reentrant.
> 
> Use a separate handler just for aio, and disable regular handlers when
> dataplane is active.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  hw/scsi/virtio-scsi-dataplane.c | 43 ++++++++++++++++++++++++---
>  hw/scsi/virtio-scsi.c           | 65 ++++++++++++++++++++++++++++-------------
>  include/hw/virtio/virtio-scsi.h |  6 ++--
>  3 files changed, 86 insertions(+), 28 deletions(-)
> 

> +static int virtio_scsi_vring_init(VirtIOSCSI *s, VirtQueue *vq, int n,
> +				  void (*fn)(VirtIODevice *vdev, VirtQueue *vq))

This function has been sadly misnamed since dataplane does not set up
its own vrings anymore. Maybe it should be called
virtio_scsi_vq_notifier_init() or so.

>  {
>      BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
>      VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);

Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>