Re: [Qemu-devel] [PATCH V2] net: fix qemu_announce_self not emitting packets

[Yang Hongyang <hongyang.yang@easystack.cn>]

On Tue, Jun 7, 2016 at 9:00 PM, Peter Lieven <pl@kamp.de> wrote:

> commit fefe2a78 accidently dropped the code path for injecting
> raw packets. This feature is needed for sending gratuitous ARPs
> after an incoming migration has completed. The result is increased
> network downtime for vservers where the network card is not virtio-net
> with the VIRTIO_NET_F_GUEST_ANNOUNCE feature.
>
> Fixes: fefe2a78abde932e0f340b21bded2c86def1d242
> Cc: qemu-stable@nongnu.org
> Cc: hongyang.yang@easystack.cn
> Signed-off-by: Peter Lieven <pl@kamp.de>
> ---
> v1->v2: assert that only raw packets with a plain buffer come in. [Paolo]
>
>  net/net.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/net/net.c b/net/net.c
> index 5f3e5a9..5e1b5fa 100644
> --- a/net/net.c
> +++ b/net/net.c
> @@ -714,6 +714,11 @@ ssize_t qemu_deliver_packet_iov(NetClientState
> *sender,
>      NetClientState *nc = opaque;
>      int ret;
>
> +    /* we currently only support sending raw packets via
> qemu_send_packet_raw.
> +     * If we want generic raw iov support we need to implement something
> like
> +     * .receive_raw_iov in NetClientInfo first. */
> +    assert(!(flags & QEMU_NET_PACKET_FLAG_RAW) || iovcnt == 1);
> +
>

This assert is hard to understand IMO...I think move assert(iovcnt==1) as
well as the
comment to if condition below as Paolo said previously is better...


>      if (nc->link_down) {
>          return iov_size(iov, iovcnt);
>      }
> @@ -722,7 +727,10 @@ ssize_t qemu_deliver_packet_iov(NetClientState
> *sender,
>          return 0;
>      }
>
> -    if (nc->info->receive_iov) {
> +    if (flags & QEMU_NET_PACKET_FLAG_RAW && nc->info->receive_raw) {
> +        /* this is required for qemu_announce_self() */
> +        ret = nc->info->receive_raw(nc, iov[0].iov_base, iov[0].iov_len);
> +    } else  if (nc->info->receive_iov) {
>          ret = nc->info->receive_iov(nc, iov, iovcnt);
>      } else {
>          ret = nc_sendv_compat(nc, iov, iovcnt, flags);
> --
> 1.9.1
>
>
>


-- 
Thanks,
Yang