netdev - Re: [PATCH net v2 8/9] bridge: Properly check if local fdb entry can be deleted when deleting vlan

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Date:	Wed, 18 Dec 2013 11:55:36 +0900
From:	Toshiaki Makita <makita.toshiaki@....ntt.co.jp>
To:	vyasevic@...hat.com
Cc:	"David S . Miller" <davem@...emloft.net>,
	Stephen Hemminger <stephen@...workplumber.org>,
	netdev@...r.kernel.org
Subject: Re: [PATCH net v2 8/9] bridge: Properly check if local fdb entry
 can be deleted when deleting vlan

On Tue, 2013-12-17 at 14:34 -0500, Vlad Yasevich wrote:
> On 12/17/2013 07:03 AM, Toshiaki Makita wrote:
> > Vlan codes unconditionally delete local fdb entries.
> > We should consider the possibility that other ports have the same
> > address and vlan.
> > 
> > Example of problematic case:
> >   ip link set eth0 address 12:34:56:78:90:ab
> >   ip link set eth1 address aa:bb:cc:dd:ee:ff
> >   brctl addif br0 eth0
> >   brctl addif br0 eth1 # br0 will have mac address 12:34:56:78:90:ab
> >   bridge vlan add dev eth0 vid 10
> >   bridge vlan add dev eth1 vid 10
> >   bridge vlan add dev br0 vid 10 self
> > We will have fdb entry such that f->dst == eth0, f->vlan_id == 10 and
> > f->addr == 12:34:56:78:90:ab at this time.
> > Next, delete eth0 vlan 10.
> >   bridge vlan del dev eth0 vid 10
> > In this case, we still need the entry for br0, but it will be deleted.
> > 
> > Note that br0 needs the entry even though its mac address is not set
> > manually. To delete the entry with proper condition checking,
> > fdb_delete_local() is suitable to use.
> > 
> > Signed-off-by: Toshiaki Makita <makita.toshiaki@....ntt.co.jp>
> 
> Acked-by: Vlad Yasevich <vyasevic@...hat.com>
> 
> Note: All these special cases are begging for something in the fdb
> to track if this fdb refers to multiple ports or not.  May be
> a list of pointers to ports?  Then we can simply check to see if
> the list is not empty and assign to the first one in the list..

Maybe the list will simplify fdb_delete_local().
The difficult point is maintaining the list properly.
I will think about it more deeply.

Thanks,
Toshiaki Makita


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