Date:   Wed, 10 Aug 2022 18:10:40 +0300
From:   Nikolay Aleksandrov <razor@...ckwall.org>
To:     Sevinj Aghayeva <sevinj.aghayeva@...il.com>
Cc:     netdev@...r.kernel.org, aroulin@...dia.com, sbrivio@...hat.com,
        roopa@...dia.com, "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, linux-kernel@...r.kernel.org,
        bridge@...ts.linux-foundation.org
Subject: Re: [PATCH RFC net-next 0/3] net: vlan: fix bridge binding behavior
 and add selftests

On 10/08/2022 18:00, Sevinj Aghayeva wrote:
> On Wed, Aug 10, 2022 at 10:50 AM Nikolay Aleksandrov
> <razor@...ckwall.org> wrote:
>>
>> On 10/08/2022 17:42, Sevinj Aghayeva wrote:
>>>
>>>
>>> On Wed, Aug 10, 2022 at 4:54 AM Nikolay Aleksandrov <razor@...ckwall.org <mailto:razor@...ckwall.org>> wrote:
>>>
>>>     On 10/08/2022 06:11, Sevinj Aghayeva wrote:
>>>     > When bridge binding is enabled for a vlan interface, it is expected
>>>     > that the link state of the vlan interface will track the subset of the
>>>     > ports that are also members of the corresponding vlan, rather than
>>>     > that of all ports.
>>>     >
>>>     > Currently, this feature works as expected when a vlan interface is
>>>     > created with bridge binding enabled:
>>>     >
>>>     >   ip link add link br name vlan10 type vlan id 10 protocol 802.1q \
>>>     >         bridge_binding on
>>>     >
>>>     > However, the feature does not work when a vlan interface is created
>>>     > with bridge binding disabled, and then enabled later:
>>>     >
>>>     >   ip link add link br name vlan10 type vlan id 10 protocol 802.1q \
>>>     >         bridge_binding off
>>>     >   ip link set vlan10 type vlan bridge_binding on
>>>     >
>>>     > After these two commands, the link state of the vlan interface
>>>     > continues to track that of all ports, which is inconsistent and
>>>     > confusing to users. This series fixes this bug and introduces two
>>>     > tests for the valid behavior.
>>>     >
>>>     > Sevinj Aghayeva (3):
>>>     >   net: core: export call_netdevice_notifiers_info
>>>     >   net: 8021q: fix bridge binding behavior for vlan interfaces
>>>     >   selftests: net: tests for bridge binding behavior
>>>     >
>>>     >  include/linux/netdevice.h                     |   2 +
>>>     >  net/8021q/vlan.h                              |   2 +-
>>>     >  net/8021q/vlan_dev.c                          |  25 ++-
>>>     >  net/core/dev.c                                |   7 +-
>>>     >  tools/testing/selftests/net/Makefile          |   1 +
>>>     >  .../selftests/net/bridge_vlan_binding_test.sh | 143 ++++++++++++++++++
>>>     >  6 files changed, 172 insertions(+), 8 deletions(-)
>>>     >  create mode 100755 tools/testing/selftests/net/bridge_vlan_binding_test.sh
>>>     >
>>>
>>>     Hi,
>>>     NETDEV_CHANGE event is already propagated when the vlan changes flags,
>>>
>>>
>>> I'm not sure if NETDEV_CHANGE is actually propagated when the vlan changes flags. The two functions in the bridge module that handle NETDEV_CHANGE are br_vlan_port_event  and br_vlan_bridge_event. I've installed probes for both, and when I'm changing flags using "sudo ip link set vlan10 type vlan bridge_binding on", I don't see any of those functions getting called, although I do see vlan_dev_change_flags getting called. I think there may be a bug in core/dev.c:__dev_notify_flags.
>>
>> are both vlan and bridge interfaces up?
>> what exactly are you probing for?
> 
> 
> I first run the attached pre.sh script that sets up the environment
> and creates a vlan interface with bridge binding off. I then start
> recording with perf, and here's the list of probes:
> 
> $ sudo ./k/linux/tools/perf/perf probe -l
>   probe:br_vlan_bridge_event (on br_vlan_bridge_event in bridge with event dev)
>   probe:br_vlan_port_event (on br_vlan_port_event in bridge with event)
>   probe:br_vlan_set_vlan_dev_state (on br_vlan_set_vlan_dev_state in
> bridge with br vlan_dev)
>   probe:register_vlan_dev (on register_vlan_dev in 8021q with dev)
>   probe:vlan_changelink (on vlan_changelink in 8021q with dev)
>   probe:vlan_dev_change_flags (on vlan_dev_change_flags in 8021q with dev)
>   probe:vlan_dev_fix_features (on vlan_dev_fix_features in 8021q with dev)
>   probe:vlan_dev_init  (on vlan_dev_init in 8021q with dev)
>   probe:vlan_dev_ioctl (on vlan_dev_ioctl in 8021q with dev)
>   probe:vlan_dev_open  (on vlan_dev_open in 8021q with dev)
>   probe:vlan_dev_stop  (on vlan_dev_stop in 8021q with dev)
>   probe:vlan_dev_uninit (on vlan_dev_uninit in 8021q with dev)
>   probe:vlan_newlink   (on vlan_newlink in 8021q with dev)
> 
> I then run the following command to turn the bridge binding flag on:
> 
> $ sudo ip link set vlan10 type vlan bridge_binding on
> 
> Then I stop the recording and print out the events, and I see this. I
> don't see br_vlan_port_event or br_vlan_bridge_event getting called.
> 
>               ip  5933 [003]  2204.722470:
> probe:vlan_changelink: (ffffffffc1042b50) dev="vlan10"
>               ip  5933 [003]  2204.722476:
> probe:vlan_dev_change_flags: (ffffffffc1042600) dev="vlan10"
> 
> Am I doing something wrong?
> 
> Thanks
> 
> 

You can't expect to see br_vlan_bridge_event() called because the notification
target device is vlan10 and not the bridge. See br_device_event():
...
        if (netif_is_bridge_master(dev)) {
                err = br_vlan_bridge_event(dev, event, ptr);
                if (err)
                        return notifier_from_errno(err);
...


Try probing for br_device_event(), you'll see it gets called every time you change the flag.

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