Re: [Qemu-devel] [PATCH 1/9] virtio-dataplane: pass assign=true to virtio_queue_aio_set_host_notifier_handler

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

On Fri,  1 Apr 2016 15:19:46 +0200
Paolo Bonzini <pbonzini@redhat.com> wrote:

> There is no need to run the handler one last time; the device is
> being reset and it is okay to drop requests that are pending in
> the virtqueue.  Even in the case of migration, the requests would
> be processed when ioeventfd is re-enabled on the destination
> side: virtio_queue_set_host_notifier_fd_handler will call
> virtio_queue_host_notifier_read, which will start dataplane; the host
> notifier is then connected to the I/O thread and event_notifier_set is
> called to start processing it.
> 
> By omitting this call, we dodge a possible cause of races between the
> dataplane thread on one side and the main/vCPU threads on the other.
> 
> The virtio_queue_aio_set_host_notifier_handler function is now
> only ever called with assign=true, but for now this is left as is
> because the function parameters will change soon anyway.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  hw/block/dataplane/virtio-blk.c | 2 +-
>  hw/scsi/virtio-scsi-dataplane.c | 6 +++---
>  2 files changed, 4 insertions(+), 4 deletions(-)

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