Re: [Qemu-devel] [PATCH v10 02/10] init/cleanup of netfilter object

["Daniel P. Berrange" <berrange@redhat.com>]

On Wed, Sep 09, 2015 at 03:24:33PM +0800, Yang Hongyang wrote:
> Add a netfilter object based on QOM.
> 
> A netfilter is attached to a netdev, captures all network packets
> that pass through the netdev. When we delete the netdev, we also
> delete the netfilter object attached to it, because if the netdev is
> removed, the filter which attached to it is useless.
> 
> QTAILQ_ENTRY global_list but used by filter layer, so that we can
> manage all filters together.
> QTAILQ_ENTRY next used by netdev, filter belongs to the specific netdev is
> in this queue.
> 
> Also init delayed object after net_init_clients, because netfilters need
> to be initialized after net clients initialized.
> 
> Signed-off-by: Yang Hongyang <yanghy@cn.fujitsu.com>

> diff --git a/net/filter.c b/net/filter.c
> new file mode 100644
> index 0000000..5192c6d
> --- /dev/null
> +++ b/net/filter.c

> +static void netfilter_init(Object *obj)
> +{
> +    QTAILQ_INIT(&net_filters);
> +    object_property_add_str(obj, "netdev",
> +                            netfilter_get_netdev_id, netfilter_set_netdev_id,
> +                            NULL);
> +    object_property_add_enum(obj, "chain", "NetFilterChain",
> +                             NetFilterChain_lookup,
> +                             netfilter_get_chain, netfilter_set_chain,
> +                             NULL);
> +}
> +
> +static void netfilter_cleanup(Object *obj)

Nit-pick, it is preferable to name methods to match the class callback
they're registered against, so if you have to re-spin a v11 plesae
rename this to netfilter_finalize.

> +{
> +    NetFilterState *nf = NETFILTER(obj);
> +    NetFilterClass *nfc = NETFILTER_GET_CLASS(obj);
> +
> +    if (nfc->cleanup) {
> +        nfc->cleanup(nf);
> +    }
> +
> +    if (nf->netdev && !QTAILQ_EMPTY(&nf->netdev->filters)) {
> +        QTAILQ_REMOVE(&nf->netdev->filters, nf, next);
> +    }
> +    if (!QTAILQ_EMPTY(&net_filters)) {
> +        QTAILQ_REMOVE(&net_filters, nf, global_list);
> +    }
> +
> +    g_free(nf->netdev_id);
> +}
> +
> +static void netfilter_complete(UserCreatable *uc, Error **errp)
> +{
> +    NetFilterState *nf = NETFILTER(uc);
> +    NetClientState *ncs[MAX_QUEUE_NUM];
> +    NetFilterClass *nfc = NETFILTER_GET_CLASS(uc);
> +    int queues;
> +    Error *local_err = NULL;
> +
> +    if (!nf->netdev_id) {
> +        error_setg(errp, "Parameter 'netdev' is required");
> +        return;
> +    }
> +
> +    queues = qemu_find_net_clients_except(nf->netdev_id, ncs,
> +                                          NET_CLIENT_OPTIONS_KIND_NIC,
> +                                          MAX_QUEUE_NUM);
> +    if (queues < 1) {
> +        error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "netdev",
> +                   "a network backend id");
> +        return;
> +    } else if (queues > 1) {
> +        error_setg(errp, "Multi queue is not supported");
> +        return;
> +    }
> +
> +    if (get_vhost_net(ncs[0])) {
> +        error_setg(errp, "Vhost is not supported");
> +        return;
> +    }
> +
> +    nf->netdev = ncs[0];
> +
> +    if (nfc->setup) {
> +        nfc->setup(nf, &local_err);
> +        if (local_err) {
> +            error_propagate(errp, local_err);
> +            return;
> +        }
> +    }
> +    QTAILQ_INSERT_TAIL(&net_filters, nf, global_list);
> +    QTAILQ_INSERT_TAIL(&nf->netdev->filters, nf, next);
> +}
> +
> +static bool netfilter_can_be_deleted(UserCreatable *uc, Error **errp)
> +{
> +    return true;
> +}

You can just leave out the netfilter_can_be_deleted() method if you are
only going to return "true", since that's the default semantics.


> +static void netfilter_class_init(ObjectClass *oc, void *data)
> +{
> +    UserCreatableClass *ucc = USER_CREATABLE_CLASS(oc);
> +
> +    ucc->complete = netfilter_complete;
> +    ucc->can_be_deleted = netfilter_can_be_deleted;
> +}
> +
> +static const TypeInfo netfilter_info = {
> +    .name = TYPE_NETFILTER,
> +    .parent = TYPE_OBJECT,
> +    .abstract = true,
> +    .class_size = sizeof(NetFilterClass),
> +    .class_init = netfilter_class_init,
> +    .instance_size = sizeof(NetFilterState),
> +    .instance_init = netfilter_init,
> +    .instance_finalize = netfilter_cleanup,
> +    .interfaces = (InterfaceInfo[]) {
> +        { TYPE_USER_CREATABLE },
> +        { }
> +    }
> +};
> +
> +static void register_types(void)
> +{
> +    type_register_static(&netfilter_info);
> +}
> +
> +type_init(register_types);
> diff --git a/vl.c b/vl.c
> index 584ca88..672f8b2 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -2783,6 +2783,7 @@ static bool object_create_initial(const char *type)
>      if (g_str_equal(type, "rng-egd")) {
>          return false;
>      }
> +    /* TODO: reture false for concrete netfilters */
>      return true;
>  }

Don't you want to be adding your object type here, alongside rng-egd
since IIRC, you said it needed to be created later

> @@ -4302,12 +4303,6 @@ int main(int argc, char **argv, char **envp)
>          exit(0);
>      }
>  
> -    if (qemu_opts_foreach(qemu_find_opts("object"),
> -                          object_create,
> -                          object_create_delayed, NULL)) {
> -        exit(1);
> -    }
> -
>      machine_opts = qemu_get_machine_opts();
>      if (qemu_opt_foreach(machine_opts, machine_set_property, current_machine,
>                           NULL)) {
> @@ -4413,6 +4408,12 @@ int main(int argc, char **argv, char **envp)
>          exit(1);
>      }
>  
> +    if (qemu_opts_foreach(qemu_find_opts("object"),
> +                          object_create,
> +                          object_create_delayed, NULL)) {
> +        exit(1);
> +    }
> +
>  #ifdef CONFIG_TPM

Regards,
Daniel
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