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

[Hailiang Zhang <zhang.zhanghailiang@huawei.com>]

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 <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

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);
>
>
> .
>