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

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Message-ID: <CAB=NE6U3o62mbDbL7Uaoe1r44xAXqW+iYM6y9jxP+UvM4kvYHw@mail.gmail.com>
Date:	Wed, 30 Apr 2014 11:38:44 -0700
From:	"Luis R. Rodriguez" <mcgrof@...not-panic.com>
To:	"Luis R. Rodriguez" <mcgrof@...not-panic.com>
Cc:	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 Tue, Apr 22, 2014 at 12:43 PM, Luis R. Rodriguez <mcgrof@...e.com> 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);
>> > >>
>> > >> 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()? How about the below
>> change?
>>
>> 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);
>>       }
>
> Cong, can you provide feedback on this? I tried to grow confidence on the
> hunk above but its not clear but the other points still hold and I'd love
> your feedback on those.

Re-poke.

  Luis
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