[ovs-dev] [patch net-next RFC 07/12] dsa: implement ndo_swdev_get_id

[Florian Fainelli]

2014-08-21 10:06 GMT-07:00 Jiri Pirko <jiri at resnulli.us>:
> Thu, Aug 21, 2014 at 06:56:13PM CEST, f.fainelli at gmail.com wrote:
>>2014-08-21 9:19 GMT-07:00 Jiri Pirko <jiri at resnulli.us>:
>>> Signed-off-by: Jiri Pirko <jiri at resnulli.us>
>>> ---
>>>  net/dsa/Kconfig |  2 +-
>>>  net/dsa/slave.c | 16 ++++++++++++++++
>>>  2 files changed, 17 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/net/dsa/Kconfig b/net/dsa/Kconfig
>>> index f5eede1..66c445a 100644
>>> --- a/net/dsa/Kconfig
>>> +++ b/net/dsa/Kconfig
>>> @@ -1,6 +1,6 @@
>>>  config HAVE_NET_DSA
>>>         def_bool y
>>> -       depends on NETDEVICES && !S390
>>> +       depends on NETDEVICES && NET_SWITCHDEV && !S390
>>>
>>>  # Drivers must select NET_DSA and the appropriate tagging format
>>>
>>> diff --git a/net/dsa/slave.c b/net/dsa/slave.c
>>> index 45a1e34..e069ba3 100644
>>> --- a/net/dsa/slave.c
>>> +++ b/net/dsa/slave.c
>>> @@ -171,6 +171,19 @@ static int dsa_slave_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
>>>         return -EOPNOTSUPP;
>>>  }
>>>
>>> +static int dsa_slave_swdev_get_id(struct net_device *dev,
>>> +                                 struct netdev_phys_item_id *psid)
>>> +{
>>> +       struct dsa_slave_priv *p = netdev_priv(dev);
>>> +       struct dsa_switch *ds = p->parent;
>>> +       u64 tmp = (u64) ds;
>>> +
>>> +       /* TODO: add more sophisticated id generation */
>>> +       memcpy(&psid->id, &tmp, sizeof(tmp));
>>> +       psid->id_len = sizeof(tmp);
>>
>>There is already an unique id generated, which is the index in the
>>switch tree, and which is stored in struct dsa_switch, so this could
>>probably be simplified to:
>>
>>psid->id = ds->index
>
> That index is 0..n if I understand that correctly. That is not enough.
> The point is to have unique id for every chip in the system. If we would
> have 0,1,2... the collision is very likely.

Good point, so an unique index for DSA switches could look like the
DSA platform device id plus the switch index in the tree..., but then
we would need something like (pdev->id << N) | switch index, so that
would not give a consistent naming scheme across different devices.

Maybe we are just better with using the Linux IDR API in include/linux/idr.h?
-- 
Florian