Linux Ethernet Bridging - Aug 2022 - [Bridge] [PATCH v4 net-next 3/6] drivers: net: dsa: add locked fdb entry flag to drivers

On 2022-08-23 09:24, Ido Schimmel wrote:
> On Tue, Aug 23, 2022 at 09:13:54AM +0200, netdev at kapio-technology.com 
> wrote:
>> On 2022-08-23 08:48, Ido Schimmel wrote:
>> > On Mon, Aug 22, 2022 at 09:49:28AM +0200, netdev at
kapio-technology.com
>> > wrote:
>> 
>> > > As I am not familiar with roaming in this context, I need to
know
>> > > how the SW
>> > > bridge should behave in this case.
>> >
>> 
>> > > In this case, is the roaming only between locked ports or
does the
>> > > roaming include that the entry can move to a unlocked port,
resulting
>> > > in the locked flag getting removed?
>> >
>> > Any two ports. If the "locked" entry in mv88e6xxx cannot
move once
>> > installed, then the "sticky" flag accurately describes
it.
>> >
>> 
>> But since I am also doing the SW bridge implementation without 
>> mv88e6xxx I
>> need it to function according to needs.
>> Thus the locked entries created in the bridge I shall not put the 
>> sticky
>> flag on, but there will be the situation where a locked entry can move 
>> to an
>> unlocked port, which we regarded as a bug.
> 
> I do not regard this as a bug. It makes sense to me that an authorized
> port can cause an entry pointing to an unauthorized port to roam to
> itself. Just like normal learned entries. What I considered as a bug is
> the fact that the "locked" flag is not cleared when roaming to an
> authorized port.
> 
>> In that case there is two possibilities, the locked entry can move to
>> an unlocked port with the locked flag being removed or the locked
>> entry can only move to another locked port?
> 
> My suggestion is to allow roaming and maintain / clear the
"locked"
> flag
> based on whether the new destination port is locked or not.
Thus I understand it as saying that the "locked" flag can also be set 
when roaming from an unlocked port to a locked port?

On Tue, Aug 23, 2022 at 09:37:54AM +0200, netdev at kapio-technology.com
wrote:
> On 2022-08-23 09:24, Ido Schimmel wrote:
> > On Tue, Aug 23, 2022 at 09:13:54AM +0200, netdev at
kapio-technology.com
> > wrote:
> > > On 2022-08-23 08:48, Ido Schimmel wrote:
> > > > On Mon, Aug 22, 2022 at 09:49:28AM +0200, netdev at
kapio-technology.com
> > > > wrote:
> > > 
> > > > > As I am not familiar with roaming in this context, I
need to know
> > > > > how the SW
> > > > > bridge should behave in this case.
> > > >
> > > 
> > > > > In this case, is the roaming only between locked ports
or does the
> > > > > roaming include that the entry can move to a unlocked
port, resulting
> > > > > in the locked flag getting removed?
> > > >
> > > > Any two ports. If the "locked" entry in mv88e6xxx
cannot move once
> > > > installed, then the "sticky" flag accurately
describes it.
> > > >
> > > 
> > > But since I am also doing the SW bridge implementation without
> > > mv88e6xxx I
> > > need it to function according to needs.
> > > Thus the locked entries created in the bridge I shall not put the
> > > sticky
> > > flag on, but there will be the situation where a locked entry can
> > > move to an
> > > unlocked port, which we regarded as a bug.
> > 
> > I do not regard this as a bug. It makes sense to me that an authorized
> > port can cause an entry pointing to an unauthorized port to roam to
> > itself. Just like normal learned entries. What I considered as a bug
is
> > the fact that the "locked" flag is not cleared when roaming
to an
> > authorized port.
> > 
> > > In that case there is two possibilities, the locked entry can
move to
> > > an unlocked port with the locked flag being removed or the locked
> > > entry can only move to another locked port?
> > 
> > My suggestion is to allow roaming and maintain / clear the
"locked" flag
> > based on whether the new destination port is locked or not.
> 
> Thus I understand it as saying that the "locked" flag can also be
set when
> roaming from an unlocked port to a locked port?
"learning on locked on" is really a misconfiguration, but it can also
happen today and entries do not roam with the "locked" flag for the
simple reason that it does not exist. I see two options:

1. Do not clear / set "locked" flag during roaming. Given learning
should be disabled on locked ports, then the only half interesting case
is roaming to an unlocked port. Keeping the "locked" flag basically
means "if you were to lock the port, then the presence of this entry is
not enough to let traffic with the SA be forwarded by the bridge".
Unlikely that anyone will do that.

2. Always set "locked" flag for learned entries (new & roamed) on
locked
ports and clear it for learned entries on unlocked ports.

Both options are consistent in how they treat the "locked" flag
(either
always do nothing or always set/clear) and both do not impact the
integrity of the solution when configured correctly (disabling learning
on locked ports). I guess users will find option 2 easier to understand
/ work with.