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

[Yang Hongyang]

On 02/01/2016 03:56 PM, Hailiang Zhang wrote:

On 2016/2/1 15:46, Jason Wang wrote:

On 02/01/2016 02:13 PM, Hailiang Zhang wrote:

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.zhanghaili...@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 ?

Yes. E.g just a global string which could be changed by any subsystem.
E.g colo may change it to "filter-buffer,interval=0,status=disable". But
filter ids need to be generated automatically.

Got it. Then we don't need the global default_netfilter_type[] in patch 5,
Just use this global string instead ?

- 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 ?

What's the reason that you want to distinguish default filters from
others?

The default filters will be used by COLO or MC, (In COLO, we will use it
to control packets buffering/releasing).
For COLO, we don't want to control (use) other filters that added by users.

I think Jason's point is that COLO is a manager, you can add the filter
to netdev when doing COLO, so the only difference between COLO's default
filter and other filter is that COLO's filter (for example buffer
filter) is added by COLO, and the other filter is added by user
specifing -filter.

Thanks,
Hailiang

Thanks

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);

.

.

--
Thanks,
Yang