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

Hi Hans,

On Thu, Jul 07, 2022 at 05:29:27PM +0200, Hans Schultz
wrote:
> Ignore locked fdb entries coming in on all drivers.
> 
> Signed-off-by: Hans Schultz <netdev at kapio-technology.com>
> ---
A good patch should have a reason for the change in the commit message.
This has no reason because there is no reason.

Think about it, you've said it yourself in patch 1:

| Only the kernel can set this FDB entry flag, while userspace can read
| the flag and remove it by replacing or deleting the FDB entry.

So if user space will never add locked FDB entries to the bridge,
then FDB entries with is_locked=true are never transported using
SWITCHDEV_FDB_ADD_TO_DEVICE to drivers, and so, there is no reason at
all to pass is_locked to drivers, just for them to ignore something that
won't appear.

You just need this for SWITCHDEV_FDB_ADD_TO_BRIDGE, so please keep it
only in those code paths, and remove it from net/dsa/slave.c as well.
>  drivers/net/dsa/b53/b53_common.c       | 5 +++++
>  drivers/net/dsa/b53/b53_priv.h         | 1 +
>  drivers/net/dsa/hirschmann/hellcreek.c | 5 +++++
>  drivers/net/dsa/lan9303-core.c         | 5 +++++
>  drivers/net/dsa/lantiq_gswip.c         | 5 +++++
>  drivers/net/dsa/microchip/ksz9477.c    | 5 +++++
>  drivers/net/dsa/mt7530.c               | 5 +++++
>  drivers/net/dsa/mv88e6xxx/chip.c       | 5 +++++
>  drivers/net/dsa/ocelot/felix.c         | 5 +++++
>  drivers/net/dsa/qca8k.c                | 5 +++++
>  drivers/net/dsa/sja1105/sja1105_main.c | 5 +++++
>  include/net/dsa.h                      | 1 +
>  net/dsa/switch.c                       | 4 ++--
>  13 files changed, 54 insertions(+), 2 deletions(-)

On 2022-07-08 10:49, Vladimir Oltean wrote:
> Hi Hans,
> 
> On Thu, Jul 07, 2022 at 05:29:27PM +0200, Hans Schultz wrote:
>> Ignore locked fdb entries coming in on all drivers.
>> 
>> Signed-off-by: Hans Schultz <netdev at kapio-technology.com>
>> ---
> 
> A good patch should have a reason for the change in the commit message.
> This has no reason because there is no reason.
> 
> Think about it, you've said it yourself in patch 1:
> 
> | Only the kernel can set this FDB entry flag, while userspace can read
> | the flag and remove it by replacing or deleting the FDB entry.
> 
> So if user space will never add locked FDB entries to the bridge,
> then FDB entries with is_locked=true are never transported using
> SWITCHDEV_FDB_ADD_TO_DEVICE to drivers, and so, there is no reason at
> all to pass is_locked to drivers, just for them to ignore something 
> that
> won't appear.
Correct me if I am wrong, but since the bridge can add locked entries, 
and
the ensuring fdb update will create a SWITCHDEV_FDB_ADD_TO_DEVICE, those 
entries
should reach the driver. The policy to ignore those in the driver can be
seen as either the right thing to do, or not yet implemented.

I remember Ido wrote at a point that the scheme they use is to trap 
various
packets to the CPU and let the bridge add the locked entry, which I then
understand is sent to the driver with a SWITCHDEV_FDB_ADD_TO_DEVICE 
event.
> 
> You just need this for SWITCHDEV_FDB_ADD_TO_BRIDGE, so please keep it
> only in those code paths, and remove it from net/dsa/slave.c as well.
> 
>>  drivers/net/dsa/b53/b53_common.c       | 5 +++++
>>  drivers/net/dsa/b53/b53_priv.h         | 1 +
>>  drivers/net/dsa/hirschmann/hellcreek.c | 5 +++++
>>  drivers/net/dsa/lan9303-core.c         | 5 +++++
>>  drivers/net/dsa/lantiq_gswip.c         | 5 +++++
>>  drivers/net/dsa/microchip/ksz9477.c    | 5 +++++
>>  drivers/net/dsa/mt7530.c               | 5 +++++
>>  drivers/net/dsa/mv88e6xxx/chip.c       | 5 +++++
>>  drivers/net/dsa/ocelot/felix.c         | 5 +++++
>>  drivers/net/dsa/qca8k.c                | 5 +++++
>>  drivers/net/dsa/sja1105/sja1105_main.c | 5 +++++
>>  include/net/dsa.h                      | 1 +
>>  net/dsa/switch.c                       | 4 ++--
>>  13 files changed, 54 insertions(+), 2 deletions(-)