On Wed, 6 Apr 2016 12:16:25 +0200
Paolo Bonzini <pbonz...@redhat.com> wrote:
> From: "Michael S. Tsirkin" <m...@redhat.com>
>
> In addition to handling IO in vcpu thread and in io thread, blk dataplane
> introduces yet another mode: handling it by AioContext.
>
> Currently, this reuses the same handler as previous modes,
> which triggers races as these were not designed to be reentrant.
> Add instead 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 <m...@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
> ---
> hw/virtio/virtio.c | 36 ++++++++++++++++++++++++++++++++----
> include/hw/virtio/virtio.h | 3 +++
> 2 files changed, 35 insertions(+), 4 deletions(-)
>
> +static void virtio_queue_notify_aio_vq(VirtQueue *vq)
> +{
> + if (vq->vring.desc && vq->handle_aio_output) {
> + VirtIODevice *vdev = vq->vdev;
> +
> + trace_virtio_queue_notify(vdev, vq - vdev->vq, vq);
> + vq->handle_aio_output(vdev, vq);
> + }
> +}
> +
So this avoids reentrancy, but might we miss one notify if
->handle_aio_output has already been unset? What am I missing?
