Re: [PATCH 4/4] virtio_net: Add a MAC filter table

Alex Williamson
2009-01-14T16:20:05Z

On Wed, 2009-01-14 at 10:15 +0000, Mark McLoughlin wrote:
> On Tue, 2009-01-13 at 14:23 -0700, Alex Williamson wrote:
> > Number of entries configurable via module param.
>
> Could do with some more details here, like explaining that it means the
> we no longer run the NIC in promiscuous mode and the guest only receives
> packets destined for it.

Yep, thanks.

> > + else {
> > + unsigned int entries;
> > +
> > + entries = mac_entries = min(mac_entries,
> > + (unsigned int)(PAGE_SIZE / ETH_ALEN));
> > + if (virtnet_send_command(vi, VIRTIO_NET_CTRL_MAC_TABLE,
> > + VIRTIO_NET_CTRL_MAC_TABLE_ALLOC,
> > + &entries, sizeof(entries)))
> > + mac_entries = 0;
> > + }
>
> Should have a warning here.

I agree.

> Also, no need for the extra variable or the case, is there?

Initially, that's what I thought too... but it doesn't work, I always
got 0 on the backend. I assume it has something to do with the memory
segment mac_entries lives in as a static variable.

> > /* Initialize our empty receive and send queues. */
> > skb_queue_head_init(&vi->recv);
> > diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
> > index 80cd7d3..31235a0 100644
> > --- a/include/linux/virtio_net.h
> > +++ b/include/linux/virtio_net.h
> > @@ -60,4 +60,8 @@ struct virtio_net_hdr_mrg_rxbuf {
> > #define VIRTIO_NET_CTRL_RX_MODE_PROMISC 0
> > #define VIRTIO_NET_CTRL_RX_MODE_ALLMULTI 1
> >
> > +#define VIRTIO_NET_CTRL_MAC_TABLE 1
> > + #define VIRTIO_NET_CTRL_MAC_TABLE_ALLOC 0
> > + #define VIRTIO_NET_CTRL_MAC_TABLE_SET 1
>
> I'd prefer:
>
> #define VIRTIO_NET_CMD_ALLOC_MAC_TABLE 1
> #define VIRTIO_NET_CMD_SET_MAC_TABLE 2

Hmm, I'm still leaning towards the class/cmd, which would allow the
backend to logically split class commands into sub-functions. But i'd
be happy to rename these to VIRTIO_NET_CMD_...

> Also, could do with some comments here to note e.g.:
>
> - alloc before set
> - subsequent allocs will fail
> - table limited to PAGE_SIZE (hmm, who's PAGE_SIZE?)
> - format of the table

Agree, thanks for the comments.

Alex

--
Alex Williamson HP Open Source & Linux Org.