Re: [virtio-dev] Clarification of VIRTIO_F_EVENT_IDX driver conditions.

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Jun 16, 2022 at 01:53:38PM -0700, Patrick Mosca wrote:
> The issue may trigger in the unlikely uint16_t overflow case of
> computing the difference between two index positions.

Are you sure this is not an implementation bug? I don't see
anywhere in the spec where we suggest computing the difference
between two index positions.

> An
> example would be a network driver where the host and guest are
> producing and consuming steadily but at different rates. The
> producer is producing faster than the consumer such that the
> consumer never needed to be notified of new events, as it is
> still playing catch up processing the queue.  If the producer
> finally catches up to the consumer and the catchup occurs just
> past the overflow point, there exists a case where a
> notification must be sent but is not sent according to the
> current ruleset. 
> 
> -Patrick Mosca

I don't see it sorry. Example?

-- 
MST


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