Linux Ethernet Bridging - Mar 2022 - [Bridge] [PATCH v2 net-next 2/4] net: switchdev: add support for offloading of fdb locked flag

On Thu, Mar 24, 2022 at 12:23:39PM +0100, Hans Schultz
wrote:
> On tor, mar 24, 2022 at 13:09, Vladimir Oltean <olteanv at gmail.com>
wrote:
> > On Thu, Mar 24, 2022 at 11:32:08AM +0100, Hans Schultz wrote:
> >> On ons, mar 23, 2022 at 16:43, Vladimir Oltean <olteanv at
gmail.com> wrote:
> >> > On Wed, Mar 23, 2022 at 01:49:32PM +0100, Hans Schultz wrote:
> >> >> >> Does someone have an idea why there at this
point is no option to add a
> >> >> >> dynamic fdb entry?
> >> >> >> 
> >> >> >> The fdb added entries here do not age out, while
the ATU entries do
> >> >> >> (after 5 min), resulting in unsynced ATU vs fdb.
> >> >> >
> >> >> > I think the expectation is to use
br_fdb_external_learn_del() if the
> >> >> > externally learned entry expires. The bridge should
not age by itself
> >> >> > FDB entries learned externally.
> >> >> >
> >> >> 
> >> >> It seems to me that something is missing then?
> >> >> My tests using trafgen that I gave a report on to Lunn
generated massive
> >> >> amounts of fdb entries, but after a while the ATU was
clean and the fdb
> >> >> was still full of random entries...
> >> >
> >> > I'm no longer sure where you are, sorry..
> >> > I think we discussed that you need to enable ATU age
interrupts in order
> >> > to keep the ATU in sync with the bridge FDB? Which means
either to
> >> > delete the locked FDB entries from the bridge when they age
out in the
> >> > ATU, or to keep refreshing locked ATU entries.
> >> > So it seems that you're doing neither of those 2 things
if you end up
> >> > with bridge FDB entries which are no longer in the ATU.
> >> 
> >> Any idea why G2 offset 5 ATUAgeIntEn (bit 10) is set? There is no
define
> >> for it, so I assume it is something default?
> >
> > No idea, but I can confirm that the out-of-reset value I see for
> > MV88E6XXX_G2_SWITCH_MGMT on 6190 and 6390 is 0x400. It's best not
to
> > rely on any reset defaults though.
> 
> I see no age out interrupts, even though the ports Age Out Int is on
> (PAV bit 14) on the locked port, and the ATU entries do age out (HoldAt1
> is off). Any idea why that can be?
> 
> I combination with this I think it would be nice to have an ability to
> set the AgeOut time even though it is not per port but global.
Sorry, I just don't know. Looking at the documentation for IntOnAgeOut,
I see it says that for an ATU entry to trigger an age out interrupt, the
port it's associated with must have IntOnAgeOut set.
But your locked ATU entries aren't associated with any port, they have
DPV=0, right? So will they never trigger any age out interrupt according
to this? I'm not clear.

On tor, mar 24, 2022 at 16:27, Vladimir Oltean <olteanv at gmail.com>
wrote:
> On Thu, Mar 24, 2022 at 12:23:39PM +0100, Hans Schultz wrote:
>> On tor, mar 24, 2022 at 13:09, Vladimir Oltean <olteanv at
gmail.com> wrote:
>> > On Thu, Mar 24, 2022 at 11:32:08AM +0100, Hans Schultz wrote:
>> >> On ons, mar 23, 2022 at 16:43, Vladimir Oltean <olteanv at
gmail.com> wrote:
>> >> > On Wed, Mar 23, 2022 at 01:49:32PM +0100, Hans Schultz
wrote:
>> >> >> >> Does someone have an idea why there at this
point is no option to add a
>> >> >> >> dynamic fdb entry?
>> >> >> >> 
>> >> >> >> The fdb added entries here do not age out,
while the ATU entries do
>> >> >> >> (after 5 min), resulting in unsynced ATU vs
fdb.
>> >> >> >
>> >> >> > I think the expectation is to use
br_fdb_external_learn_del() if the
>> >> >> > externally learned entry expires. The bridge
should not age by itself
>> >> >> > FDB entries learned externally.
>> >> >> >
>> >> >> 
>> >> >> It seems to me that something is missing then?
>> >> >> My tests using trafgen that I gave a report on to
Lunn generated massive
>> >> >> amounts of fdb entries, but after a while the ATU was
clean and the fdb
>> >> >> was still full of random entries...
>> >> >
>> >> > I'm no longer sure where you are, sorry..
>> >> > I think we discussed that you need to enable ATU age
interrupts in order
>> >> > to keep the ATU in sync with the bridge FDB? Which means
either to
>> >> > delete the locked FDB entries from the bridge when they
age out in the
>> >> > ATU, or to keep refreshing locked ATU entries.
>> >> > So it seems that you're doing neither of those 2
things if you end up
>> >> > with bridge FDB entries which are no longer in the ATU.
>> >> 
>> >> Any idea why G2 offset 5 ATUAgeIntEn (bit 10) is set? There is
no define
>> >> for it, so I assume it is something default?
>> >
>> > No idea, but I can confirm that the out-of-reset value I see for
>> > MV88E6XXX_G2_SWITCH_MGMT on 6190 and 6390 is 0x400. It's best
not to
>> > rely on any reset defaults though.
>> 
>> I see no age out interrupts, even though the ports Age Out Int is on
>> (PAV bit 14) on the locked port, and the ATU entries do age out
(HoldAt1
>> is off). Any idea why that can be?
>> 
>> I combination with this I think it would be nice to have an ability to
>> set the AgeOut time even though it is not per port but global.
>
> Sorry, I just don't know. Looking at the documentation for IntOnAgeOut,
> I see it says that for an ATU entry to trigger an age out interrupt, the
> port it's associated with must have IntOnAgeOut set.
> But your locked ATU entries aren't associated with any port, they have
> DPV=0, right? So will they never trigger any age out interrupt according
> to this? I'm not clear.
I think that's absolutely right. That leaves two options. Either "port
10" if it has IntOnAgeOut setting, or the reason why I wrote my comments
in this part of the code, that it should be able to add a dynamic entry
in the bridge module from the driver.

On tor, mar 24, 2022 at 16:27, Vladimir Oltean <olteanv at gmail.com>
wrote:
> On Thu, Mar 24, 2022 at 12:23:39PM +0100, Hans Schultz wrote:
>> On tor, mar 24, 2022 at 13:09, Vladimir Oltean <olteanv at
gmail.com> wrote:
>> > On Thu, Mar 24, 2022 at 11:32:08AM +0100, Hans Schultz wrote:
>> >> On ons, mar 23, 2022 at 16:43, Vladimir Oltean <olteanv at
gmail.com> wrote:
>> >> > On Wed, Mar 23, 2022 at 01:49:32PM +0100, Hans Schultz
wrote:
>> >> >> >> Does someone have an idea why there at this
point is no option to add a
>> >> >> >> dynamic fdb entry?
>> >> >> >> 
>> >> >> >> The fdb added entries here do not age out,
while the ATU entries do
>> >> >> >> (after 5 min), resulting in unsynced ATU vs
fdb.
>> >> >> >
>> >> >> > I think the expectation is to use
br_fdb_external_learn_del() if the
>> >> >> > externally learned entry expires. The bridge
should not age by itself
>> >> >> > FDB entries learned externally.
>> >> >> >
>> >> >> 
>> >> >> It seems to me that something is missing then?
>> >> >> My tests using trafgen that I gave a report on to
Lunn generated massive
>> >> >> amounts of fdb entries, but after a while the ATU was
clean and the fdb
>> >> >> was still full of random entries...
>> >> >
>> >> > I'm no longer sure where you are, sorry..
>> >> > I think we discussed that you need to enable ATU age
interrupts in order
>> >> > to keep the ATU in sync with the bridge FDB? Which means
either to
>> >> > delete the locked FDB entries from the bridge when they
age out in the
>> >> > ATU, or to keep refreshing locked ATU entries.
>> >> > So it seems that you're doing neither of those 2
things if you end up
>> >> > with bridge FDB entries which are no longer in the ATU.
>> >> 
>> >> Any idea why G2 offset 5 ATUAgeIntEn (bit 10) is set? There is
no define
>> >> for it, so I assume it is something default?
>> >
>> > No idea, but I can confirm that the out-of-reset value I see for
>> > MV88E6XXX_G2_SWITCH_MGMT on 6190 and 6390 is 0x400. It's best
not to
>> > rely on any reset defaults though.
>> 
>> I see no age out interrupts, even though the ports Age Out Int is on
>> (PAV bit 14) on the locked port, and the ATU entries do age out
(HoldAt1
>> is off). Any idea why that can be?
>> 
>> I combination with this I think it would be nice to have an ability to
>> set the AgeOut time even though it is not per port but global.
>
> Sorry, I just don't know. Looking at the documentation for IntOnAgeOut,
> I see it says that for an ATU entry to trigger an age out interrupt, the
> port it's associated with must have IntOnAgeOut set.
> But your locked ATU entries aren't associated with any port, they have
> DPV=0, right? So will they never trigger any age out interrupt according
> to this? I'm not clear.
If it could be possible to add a dynamic entry to the bridge module from
the driver, that would be a solution, and since in the ATU in this case
ages out entries learned, I don't see why __br_fdb_add() insists that an
external learned entry must be permanent?