netdev - Re: [PATCH 2/3] bridge: trigger a bridge calculation upon port changes

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Message-ID: <53619153.8020404@gmail.com>
Date:	Wed, 30 Apr 2014 20:12:03 -0400
From:	Vlad Yasevich <vyasevich@...il.com>
To:	"Luis R. Rodriguez" <mcgrof@...e.com>
CC:	"Luis R. Rodriguez" <mcgrof@...not-panic.com>,
	Cong Wang <cwang@...pensource.com>,
	netdev <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	kvm@...r.kernel.org, xen-devel@...ts.xenproject.org,
	Stephen Hemminger <stephen@...workplumber.org>,
	bridge@...ts.linux-foundation.org
Subject: Re: [PATCH 2/3] bridge: trigger a bridge calculation upon port changes

On 04/30/2014 06:59 PM, Luis R. Rodriguez wrote:
> On Wed, Apr 30, 2014 at 04:04:34PM -0400, Vlad Yasevich wrote:
>> On 04/22/2014 03:43 PM, Luis R. Rodriguez wrote:
>>> diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
>>> index 54d207d..dcd9378 100644
>>> --- a/net/bridge/br_if.c
>>> +++ b/net/bridge/br_if.c
>>> @@ -315,6 +315,8 @@ netdev_features_t br_features_recompute(struct net_bridge *br,
>>>  	features &= ~NETIF_F_ONE_FOR_ALL;
>>>  
>>>  	list_for_each_entry(p, &br->port_list, list) {
>>> +		if (p->flags & BR_ROOT_BLOCK)
>>> +			continue;
>>>  		features = netdev_increment_features(features,
>>>  						     p->dev->features, mask);
>>>  	}
>>>
>> Hi Luis
>>
>> The hunk above isn't right.  Just because you set ROOT_BLOCK on the port
>> doesn't mean that you should ignore it's device features.  If the device
>> you just added happens to disable or enable some device offload feature,
>> you should take that into account.
> 
> OK thanks, how about this part:
> 
> On 04/22/2014 03:43 PM, Luis R. Rodriguez wrote:
>> On Tue, Mar 18, 2014 at 02:22:43PM -0700, Luis R. Rodriguez wrote:
>> On Tue, Mar 18, 2014 at 01:46:49PM -0700, Cong Wang wrote:
>>> On Fri, Mar 14, 2014 at 6:39 PM, Luis R. Rodriguez <mcgrof@...e.com> wrote:
>>>> On Thu, Mar 13, 2014 at 11:26:25AM -0700, Cong Wang wrote:
>>>>> On Wed, Mar 12, 2014 at 8:15 PM, Luis R. Rodriguez
>>>>> <mcgrof@...not-panic.com> wrote:
>>>>>>                         spin_unlock_bh(&p->br->lock);
>>>>>> +                       if (changed)
>>>>>> +                               call_netdevice_notifiers(NETDEV_CHANGEADDR,
>>>>>> +                                                        p->br->dev);
>>>>>> +                       netdev_update_features(p->br->dev);
>>>>>

This is actually just a part of it.  You also need to handle the sysfs
changing the flag.

Look at the first 2 patches in this series:
http://www.spinics.net/lists/netdev/msg280863.html

You might need that functionality.

-vlad


>>>>> I think this is supposed to be in netdev event handler of br->dev
>>>>> instead of here.
>>>>
>>>> Do you mean netdev_update_features() ? I mimic'd what was being done on
>>>> br_del_if() given that root blocking is doing something similar. If
>>>> we need to change something for the above then I suppose it means we need
>>>> to change br_del_if() too. Let me know if you see any reason for something
>>>> else.
>>>>
>>>
>>> Yeah, for me it looks like it's better to call netdev_update_features()
>>> in the event handler of br->dev, rather than where calling
>>> call_netdevice_notifiers(..., br->dev);.
>>
>> I still don't see why, in fact trying to verify this I am wondering now
>> if instead we should actually fix br_features_recompute() to take into
>> consideration BR_ROOT_BLOCK as below. Notice how netdev_update_features()
>> is called above even if the MAC address did not change, just as is done
>> on br_del_if(). There is an NETDEV_FEAT_CHANGE event so would it be more
>> appropriate we just call
>>
>> call_netdevice_notifiers(NETDEV_FEAT_CHANGE, p->br->dev)
>>
>> for both the above then and also br_del_if()?
> 
>   Luis
> 

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