Re: [Qemu-devel] [PATCH for-2.6] virtio: Register host notifier handler as external

[Kevin Wolf <kwolf@redhat.com>]

Am 21.04.2016 um 07:05 hat Fam Zheng geschrieben:
> On Thu, 04/21 10:04, Fam Zheng wrote:
> > This ensures the bdrv_drained_begin() in block layer is effective and
> > fixes launchpad bug #1570134.
> 
> Forgot to add to the subject, but this patch is for 2.6.

Also CCing qemu-stable (this affects 2.5) and qemu-block.

> > Signed-off-by: Fam Zheng <famz@redhat.com>
> > ---
> >  hw/virtio/virtio.c | 7 ++++---
> >  1 file changed, 4 insertions(+), 3 deletions(-)
> > 
> > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> > index f745c4a..002c2c6 100644
> > --- a/hw/virtio/virtio.c
> > +++ b/hw/virtio/virtio.c
> > @@ -1829,10 +1829,11 @@ void virtio_queue_set_host_notifier_fd_handler(VirtQueue *vq, bool assign,
> >                                                 bool set_handler)
> >  {
> >      if (assign && set_handler) {
> > -        event_notifier_set_handler(&vq->host_notifier,
> > -                                   virtio_queue_host_notifier_read);
> > +        aio_set_event_notifier(qemu_get_aio_context(), &vq->host_notifier,
> > +                               true, virtio_queue_host_notifier_read);
> >      } else {
> > -        event_notifier_set_handler(&vq->host_notifier, NULL);
> > +        aio_set_event_notifier(qemu_get_aio_context(), &vq->host_notifier,
> > +                               true, NULL);
> >      }

This feels like fixing one special case of a more general problem. Are
we sure that event_notifier_set_handler() should ever result in an
internal handler? The default should probably be external, and block
drivers need to take care to use functions that have the is_external
parameter so they can mark themselves internal.

Kevin