Re: [Qemu-devel] [PATCH v8 03/11] netfilter: add netfilter_{add|del} commands

[Yang Hongyang]

On 08/31/2015 10:53 PM, Eric Blake wrote:
> On 08/31/2015 03:01 AM, Yang Hongyang wrote:
>
> > Sorry that I don't know much about the QAPI part, I have a question, in
> > previous reply, Eric suggested:
> >    >
> >    > Then this becomes something like:
> >    >
> >    >     { 'command': 'netfilter-add', 'data': 'NetFilter' }
>
> If we do this (which requires pending patches to be flushed), then the
> user specifies the following QMP:
>
> { "execute":"netfilter-add",
>    "arguments":{ "id":"abc", "netdev":"def", "type":"dummy" }}
>
> >    or use NetFilter as a union, but have the command be:
> >
> >    { 'command': 'netfilter-add',
> >      'data': { 'data': 'NetFilter' } }
>
> This approach would work right now without waiting for pending qapi
> commits, but the QMP command would look like:
>
> { "execute":"netfilter-add",
> "arguments":{ "data":{ "id":"abc", "netdev":"def", "type":"dummy" }}}
>
> >    where you have to pass an extra layer of nesting at the QMP layer.
> >
> > What do you mean by pass an extra layer of nesting?
>
> The fact that I had to pass "arguments":{"data":{...}}, thereby nesting
> the real options inside another relatively pointless data wrapper.

Now I understand, with the flat union, all I need to do now is to specify the
command schema like:
    { 'command': 'netfilter-add',
      'data': { 'data': 'NetFilter' } }
and use the qmp command like you noted above.

Thanks a lot Eric!

> > I've already switched to flat union as you suggested:
> >
> > { 'struct': 'NetFilterDummyOptions',
> >    'data': { } }
> >
> > { 'enum': 'NetFilterType',
> >    'data': ['dummy'] }
> >
> > { 'struct': 'NetFilterBase',
> >    'data': {
> >      'id':   'str',
> >      'netdev': 'str',
> >      '*chain': 'str',
> >      'type': 'NetFilterType' } }
> >
> > { 'union': 'NetFilter',
> >    'base': 'NetFilterBase',
> >    'discriminator': 'type',
> >    'data': {
> >      'dummy': 'NetFilterDummyOptions' } }
>
> Looks reasonable for a first round.  Some of the pending qapi commits
> may allow us to further simplify things to not be quite so verbose, but
> that doesn't stop us from using this now.

--
Thanks,
Yang.