netdev - Re: [PATCH net-next 4/6] bridge: a netlink notification should be sent when those attributes are changed by br_sysfs

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Message-ID: <56E96EAC.2080109@cumulusnetworks.com>
Date:	Wed, 16 Mar 2016 15:33:16 +0100
From:	Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
To:	Xin Long <lucien.xin@...il.com>
Cc:	network dev <netdev@...r.kernel.org>, davem <davem@...emloft.net>,
	Hannes Frederic Sowa <hannes@...essinduktion.org>
Subject: Re: [PATCH net-next 4/6] bridge: a netlink notification should be
 sent when those attributes are changed by br_sysfs_br

On 03/16/2016 03:29 PM, Xin Long wrote:
> On Wed, Mar 16, 2016 at 10:14 PM, Nikolay Aleksandrov
> <nikolay@...ulusnetworks.com> wrote:
>> On 03/16/2016 02:34 PM, Xin Long wrote:
>>> Now when we change the attributes of bridge or br_port by netlink,
>>> a relevant netlink notification will be sent, but if we change them
>>> by ioctl or sysfs, no notification will be sent.
>>>
>>> We should ensure that whenever those attributes change internally or from
>>> sysfs/ioctl, that a netlink notification is sent out to listeners.
>>>
>>> Also, NetworkManager will use this in the future to listen for out-of-band
>>> bridge master attribute updates and incorporate them into the runtime
>>> configuration.
>>>
>>> This patch is used for br_sysfs_br. and we also need to remove some
>>> rtnl_trylock in old functions so that we can call it in a common one.
>>>
>>> Signed-off-by: Xin Long <lucien.xin@...il.com>
>>> ---
>>>  net/bridge/br_sysfs_br.c | 17 ++++++++---------
>>>  net/bridge/br_vlan.c     | 30 +++++-------------------------
>>>  2 files changed, 13 insertions(+), 34 deletions(-)
>>>
>>
>> What about the group_addr option ? Changing it will not generate a notification.
>>
>>
> 
> group_addr is not a string-to-long convert in sysfs. so it's hard to use
> store_bridge_parm, that's why I didn't modify it.
> 
> in group_addr_store():
> it also tries to hold rtnl_lock. maybe we can send rtnl msg there.
> what do you think?
Sounds good.

> 
> when I cooked this patch, I was wondering why br_recalculate_fwd_mask
> "Must be protected by RTNL."
> 
vlan_enabled and vlan_proto are changed under rtnl, also this can race with
changing via netlink