Re: [Qemu-devel] [PATCH 5/9] virtio: add aio handler

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

On Wed, 30 Mar 2016 14:48:04 +0200
Paolo Bonzini <pbonzini@redhat.com> wrote:

> From: "Michael S. Tsirkin" <mst@redhat.com>
> 
> In addition to handling IO in vcpu thread and
> in io thread, blk 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.
> 
> As a temporary fix, add a separate handler just for aio, this will make
> it possible to disable regular handlers when dataplane is active.
> 
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  hw/virtio/virtio.c         | 36 ++++++++++++++++++++++++++++++++----
>  include/hw/virtio/virtio.h |  3 +++
>  2 files changed, 35 insertions(+), 4 deletions(-)
> 

> @@ -1791,14 +1811,22 @@ void virtio_queue_aio_set_host_notifier_handler(VirtQueue *vq, AioContext *ctx,
>  {
>      if (assign && set_handler) {
>          aio_set_event_notifier(ctx, &vq->host_notifier, true,
> -                               virtio_queue_host_notifier_read);
> +                               virtio_queue_host_notifier_aio_read);
>      } else {
>          aio_set_event_notifier(ctx, &vq->host_notifier, true, NULL);
>      }
>      if (!assign) {
>          /* Test and clear notifier before after disabling event,
>           * in case poll callback didn't have time to run. */
> -        virtio_queue_host_notifier_read(&vq->host_notifier);
> +        virtio_queue_host_notifier_aio_read(&vq->host_notifier);

Is this function ever called with assign==false anymore after patch 1?

> +    }
> +}