On 12/05/2021 15:15, Patrick Wildt wrote:
> Hi,
>
> when hvn(4) attaches it sends commands and waits for replies to come
> back in, hence the interrupt function is being polled. Unfortunately
> it seems that the 'receive pipe' has both command completion and data
> packets. As it turns out, while hvn(4) is just setting up the pipes,
> it can already receive packets, which I have seen happening on Hyper-V.
>
> This essentially means that if_input() is being called *before* the
> card is set up (or UP). This seems wrong. Apparently on drivers like
> em(4) we only read packets if IFF_RUNNING is set. I think in the case
> of hvn(4), we should drop packets unless IFF_RUNNING is set.
>
> Opinions?
>
Hi Patrick,
You're right that hvn needs to have the receiving path setup to exchange
commands with the hypervisor. This diff LGTM and should be committed if
it wasn't.
Cheers,
Mike
> Patrick
>
> diff --git a/sys/dev/pv/if_hvn.c b/sys/dev/pv/if_hvn.c
> index f12e2f935ca..4306f717baf 100644
> --- a/sys/dev/pv/if_hvn.c
> +++ b/sys/dev/pv/if_hvn.c
> @@ -1470,7 +1470,10 @@ hvn_rndis_input(struct hvn_softc *sc, uint64_t tid,
> void *arg)
> }
> hvn_nvs_ack(sc, tid);
>
> - if_input(ifp, &ml);
> + if (ifp->if_flags & IFF_RUNNING)
> + if_input(ifp, &ml);
> + else
> + ml_purge(&ml);
> }
>
> static inline struct mbuf *
>
