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

[Jason Wang <jasowang@redhat.com>]

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 <zhang.zhanghailiang@huawei.com>
> ---
> 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
- 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"
- no need to have a special flag like "is_default"

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);