Re: [Qemu-devel] [PATCH RFC v2 3/5] net/filter: Introduce a helper to add a filter to the netdev

[Hailiang Zhang]

On 2016/2/1 11:14, Jason Wang wrote:
> On 01/27/2016 04:29 PM, zhanghailiang wrote:
> > We add a new helper function netdev_add_filter(), this function
> > can help adding a filter object to a netdev.
> > Besides, we add a is_default member for struct NetFilterState
> > to indicate whether the filter is default or not.
> >
> > Signed-off-by: zhanghailiang <address@hidden>
> > ---
> > v2:
> >   -Re-implement netdev_add_filter() by re-using object_create()
> >    (Jason's suggestion)
> > ---
> >   include/net/filter.h |  7 +++++
> >   net/filter.c         | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> >   2 files changed, 87 insertions(+)
> >
> > diff --git a/include/net/filter.h b/include/net/filter.h
> > index af3c53c..ee1c024 100644
> > --- a/include/net/filter.h
> > +++ b/include/net/filter.h
> > @@ -55,6 +55,7 @@ struct NetFilterState {
> >       char *netdev_id;
> >       NetClientState *netdev;
> >       NetFilterDirection direction;
> > +    bool is_default;
> >       bool enabled;
> >       QTAILQ_ENTRY(NetFilterState) next;
> >   };
> > @@ -74,4 +75,10 @@ ssize_t qemu_netfilter_pass_to_next(NetClientState *sender,
> >                                       int iovcnt,
> >                                       void *opaque);
> >
> > +void netdev_add_filter(const char *netdev_id,
> > +                       const char *filter_type,
> > +                       const char *id,
> > +                       bool is_default,
> > +                       Error **errp);
> > +
> >   #endif /* QEMU_NET_FILTER_H */
> > diff --git a/net/filter.c b/net/filter.c
> > index d08a2be..dc7aa9b 100644
> > --- a/net/filter.c
> > +++ b/net/filter.c
> > @@ -214,6 +214,86 @@ static void netfilter_complete(UserCreatable *uc, Error 
> > **errp)
> >       QTAILQ_INSERT_TAIL(&nf->netdev->filters, nf, next);
> >   }
> >
> > +QemuOptsList qemu_filter_opts = {
> > +    .name = "default-filter",
> > +    .head = QTAILQ_HEAD_INITIALIZER(qemu_filter_opts.head),
> > +    .desc = {
> > +        {
> > +            .name = "qom-type",
> > +            .type = QEMU_OPT_STRING,
> > +        },{
> > +            .name = "id",
> > +            .type = QEMU_OPT_STRING,
> > +        },{
> > +            .name = "netdev",
> > +            .type = QEMU_OPT_STRING,
> > +        },{
> > +            .name = "status",
> > +            .type = QEMU_OPT_STRING,
> > +        },
> > +        { /* end of list */ }
> > +    },
> > +};
> > +
> > +static void filter_set_default_flag(const char *id,
> > +                                    bool is_default,
> > +                                    Error **errp)
> > +{
> > +    Object *obj, *container;
> > +    NetFilterState *nf;
> > +
> > +    container = object_get_objects_root();
> > +    obj = object_resolve_path_component(container, id);
> > +    if (!obj) {
> > +        error_setg(errp, "object id not found");
> > +        return;
> > +    }
> > +    nf = NETFILTER(obj);
> > +    nf->is_default = is_default;
> > +}
> > +
> > +void netdev_add_filter(const char *netdev_id,
> > +                       const char *filter_type,
> > +                       const char *id,
> > +                       bool is_default,
> > +                       Error **errp)
> > +{
> > +    NetClientState *nc = qemu_find_netdev(netdev_id);
> > +    char *optarg;
> > +    QemuOpts *opts = NULL;
> > +    Error *err = NULL;
> > +
> > +    /* FIXME: Not support multiple queues */
> > +    if (!nc || nc->queue_index > 1) {
> > +        return;
> > +    }
> > +    /* Not support vhost-net */
> > +    if (get_vhost_net(nc)) {
> > +        return;
> > +    }
> > +
> > +    optarg = g_strdup_printf("qom-type=%s,id=%s,netdev=%s,status=%s",
> > +            filter_type, id, netdev_id, is_default ? "disable" : "enable"
>
> Instead of this, I wonder maybe it's better to:
>
> - store the default filter property into a pointer to string

Do you mean, pass a string parameter which stores the filter property instead of
assemble it in this helper ?

> - colo code may change the pointer to "filter-buffer,status=disable"

> Then, there's no need for lots of codes above:
> - no need a "is_default" parameter in netdev_add_filter which does not
> scale consider we may want to have more property in the future
> - no need to hacking like "qemu_filter_opts"

Yes, we can use qemu_find_opts("object") instead of it.

> - no need to have a special flag like "is_default"

But we have to distinguish the default filter from the common
filter, use the name (id) to distinguish it ?

Thanks,
Hailiang

> Thoughts?
>
> > +    opts = qemu_opts_parse_noisily(&qemu_filter_opts,
> > +                                   optarg, false);
> > +    if (!opts) {
> > +        error_report("Failed to parse param '%s'", optarg);
> > +        exit(1);
> > +    }
> > +    g_free(optarg);
> > +    if (object_create(NULL, opts, &err) < 0) {
> > +        error_report("Failed to create object");
> > +        goto out_clean;
> > +    }
> > +    filter_set_default_flag(id, is_default, &err);
> > +
> > +out_clean:
> > +    qemu_opts_del(opts);
> > +    if (err) {
> > +        error_propagate(errp, err);
> > +    }
> > +}
> > +
> >   static void netfilter_finalize(Object *obj)
> >   {
> >       NetFilterState *nf = NETFILTER(obj);
>
>
> .