Re: [PATCH 6/7] vhost: Always store new kick fd on vhost_svq_set_svq_kick_fd

[Jason Wang <jasowang@redhat.com>]

在 2022/8/20 00:53, Eugenio Pérez 写道:
> We can unbind twice a file descriptor if we call twice
> vhost_svq_set_svq_kick_fd because of this. Since it comes from vhost and
> not from SVQ, that file descriptor could be a different thing that
> guest's vhost notifier.
>
> Likewise, it can happens the same if a guest start and stop the device
> multiple times.
>
> Reported-by: Lei Yang <leiyang@redhat.com>
> Fixes: dff4426fa6 ("vhost: Add Shadow VirtQueue kick forwarding capabilities")
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> ---


Acked-by: Jason Wang <jasowang@redhat.com>


>   hw/virtio/vhost-shadow-virtqueue.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/hw/virtio/vhost-shadow-virtqueue.c b/hw/virtio/vhost-shadow-virtqueue.c
> index e4956728dd..82a784d250 100644
> --- a/hw/virtio/vhost-shadow-virtqueue.c
> +++ b/hw/virtio/vhost-shadow-virtqueue.c
> @@ -602,13 +602,13 @@ void vhost_svq_set_svq_kick_fd(VhostShadowVirtqueue *svq, int svq_kick_fd)
>           event_notifier_set_handler(svq_kick, NULL);
>       }
>   
> +    event_notifier_init_fd(svq_kick, svq_kick_fd);
>       /*
>        * event_notifier_set_handler already checks for guest's notifications if
>        * they arrive at the new file descriptor in the switch, so there is no
>        * need to explicitly check for them.
>        */
>       if (poll_start) {
> -        event_notifier_init_fd(svq_kick, svq_kick_fd);
>           event_notifier_set(svq_kick);
>           event_notifier_set_handler(svq_kick, vhost_handle_guest_kick_notifier);
>       }
> @@ -655,7 +655,7 @@ void vhost_svq_start(VhostShadowVirtqueue *svq, VirtIODevice *vdev,
>    */
>   void vhost_svq_stop(VhostShadowVirtqueue *svq)
>   {
> -    event_notifier_set_handler(&svq->svq_kick, NULL);
> +    vhost_svq_set_svq_kick_fd(svq, VHOST_FILE_UNBIND);
>       g_autofree VirtQueueElement *next_avail_elem = NULL;
>   
>       if (!svq->vq) {