netdev - Re: [PATCH 1/6] bridge: add support to parse multiple vlan info attributes in IFLA_AF

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Message-ID: <CAE4R7bDjmHrW+bzoPJ-fpN51ykTnqjrXy7hCqXgJNv-EHayiHg@mail.gmail.com>
Date:	Mon, 29 Dec 2014 21:31:45 -0800
From:	Scott Feldman <sfeldma@...il.com>
To:	roopa <roopa@...ulusnetworks.com>
Cc:	Netdev <netdev@...r.kernel.org>, shemminger@...tta.com,
	"vyasevic@...hat.com" <vyasevic@...hat.com>,
	Wilson Kok <wkok@...ulusnetworks.com>
Subject: Re: [PATCH 1/6] bridge: add support to parse multiple vlan info
 attributes in IFLA_AF_SPEC

On Mon, Dec 29, 2014 at 9:25 PM, roopa <roopa@...ulusnetworks.com> wrote:
> On 12/29/14, 4:26 PM, Scott Feldman wrote:
>>
>> On Mon, Dec 29, 2014 at 4:07 PM, Scott Feldman <sfeldma@...il.com> wrote:
>>>
>>> On Mon, Dec 29, 2014 at 3:47 PM, Scott Feldman <sfeldma@...il.com> wrote:
>>>>
>>>> On Mon, Dec 29, 2014 at 2:10 PM, roopa <roopa@...ulusnetworks.com>
>>>> wrote:
>>>>>
>>>>> On 12/29/14, 1:40 PM, Scott Feldman wrote:
>>>>>>
>>>>>> On Mon, Dec 29, 2014 at 1:05 PM,  <roopa@...ulusnetworks.com> wrote:
>>>>>>>
>>>>>>> From: Roopa Prabhu <roopa@...ulusnetworks.com>
>>>>>>>
>>>>>>> This patch changes bridge IFLA_AF_SPEC netlink attribute parser to
>>>>>>> look for more than one IFLA_BRIDGE_VLAN_INFO attribute. This allows
>>>>>>> userspace to pack more than one vlan in the setlink msg.
>>>>>>>
>>>>>>> Signed-off-by: Roopa Prabhu <roopa@...ulusnetworks.com>
>>>>>>> ---
>>>>>>>    net/bridge/br_netlink.c |   18 +++++++++---------
>>>>>>>    1 file changed, 9 insertions(+), 9 deletions(-)
>>>>>>>
>>>>>>> diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
>>>>>>> index 9f5eb55..75971b1 100644
>>>>>>> --- a/net/bridge/br_netlink.c
>>>>>>> +++ b/net/bridge/br_netlink.c
>>>>>>> @@ -230,18 +230,18 @@ static int br_afspec(struct net_bridge *br,
>>>>>>>                        struct nlattr *af_spec,
>>>>>>>                        int cmd)
>>>>>>>    {
>>>>>>> -       struct nlattr *tb[IFLA_BRIDGE_MAX+1];
>>>>>>> +       struct bridge_vlan_info *vinfo;
>>>>>>>           int err = 0;
>>>>>>> +       struct nlattr *attr;
>>>>>>> +       int err = 0;
>>>>>>> +       int rem;
>>>>>>> +       u16 vid;
>>>>>>>
>>>>>>> -       err = nla_parse_nested(tb, IFLA_BRIDGE_MAX, af_spec,
>>>>>>> ifla_br_policy);
>>>>>>
>>>>>> Removing this call orphans ifla_br_policy...should ifla_br_policy be
>>>>>> removed?
>>>>>
>>>>>
>>>>> good question. Its a good place to see the type. In-fact userspace
>>>>> programs
>>>>> also copy the same policy to parse netlink attributes. hmmm..
>>>>> I would like to keep it if it does not throw a warning.
>>>>
>>>> I don't know what the policy (sorry, no pun intended) on leaving dead
>>>> code.  I say remove it.
>>>
>>> You know, not using the policy seems like a step backwards, and maybe
>>> it suggests a problem with the attr packing.
>>>
>>> We had:
>>>
>>> ifla_br_policy
>>>     IFLA_BRIDGE_FLAGS
>>>     IFLA_BRIDGE_MODE
>>>     IFLA_BRIDGE_VLAN_INFO
>>>
>>> This patch set makes it:
>>>
>>> ifla_br_policy
>>>     IFLA_BRIDGE_FLAGS
>>>     IFLA_BRIDGE_MODE
>>>     IFLA_BRIDGE_VLAN_INFO
>>>     IFLA_BRIDGE_VLAN_RANGE_INFO
>>>
>>> Which is fine, but now VLAN_INFO and VLAN_RANGE_INFO can be repeated.
>>> I think you want some nesting to clarify:
>>>
>>> ifla_br_policy
>>>     IFLA_BRIDGE_FLAGS
>>>     IFLA_BRIDGE_MODE
>>>     IFLA_BRIDGE_VLAN_INFO
>>>     IFLA_BRIDGE_VLAN_LIST_INFO    // nested array of
>>>         IFLA_BRIDGE_VLAN_INFO
>>>         IFLA_BRIDGE_VLAN_RANGE_INFO
>>>
>>> Now you can keep the policy for the top-level parsing, and loop only
>>> on the nested array VLAN_LIST_INFO.  Actually, now you can use just
>>> RANGE_INFO in array and have:
>>>
>>> ifla_br_policy
>>>     IFLA_BRIDGE_FLAGS
>>>     IFLA_BRIDGE_MODE
>>>     IFLA_BRIDGE_VLAN_INFO
>>>     IFLA_BRIDGE_VLAN_LIST_INFO    // nested array of
>>>         IFLA_BRIDGE_VLAN_RANGE_INFO
>>>
>>> And use VLAN_RANGE_INFO for both ranges of vids as well as single
>>> vids.  That'll simplify your filling algo in patch 5.
>>
>> Hmmmm...do you even need VLAN_RANGE_INFO?  How about just using
>> existing VLAN_INFO and add some more flags:
>>
>> #define BRIDGE_VLAN_INFO_RANGE_START    (1<<3)
>> #define BRIDGE_VLAN_INFO_RANGE_END        (1<<4)
>>
>> Now you can have:
>>
>>     IFLA_BRIDGE_FLAGS
>>     IFLA_BRIDGE_MODE
>>     IFLA_BRIDGE_VLAN_INFO
>>     IFLA_BRIDGE_VLAN_INFO_LIST    // nested array of
>>         IFLA_BRIDGE_VLAN_INFO
>>
>> Don't set START or END for single vids in list.
>
>
> ok. I was debating yesterday about introducing another nest. This looks
> good.
> My only reason to not use existing IFLA_BRIDGE_VLAN_INFO was to make sure it
> works for existing users.
> I see that in this case since IFLA_BRIDGE_VLAN_INFO_LIST is new, it will not
> affect existing users.
>
> But, i cant use IFLA_BRIDGE_VLAN_INFO (ie an attribute in ifla_br_policy)
> under IFLA_BRIDGE_VLAN_INFO_LIST ?.

I don't see why not.  You're not going to parse the array with a
policy anyway (since it's an array).  And attr INFO_LIST will be .type
= NLA_NESTED in ifla_br_policy.

>
> IFLA_BRIDGE_VLAN_INFO_LIST will have its own policy and its own attributes.
>
> Which will make it look something like below ?
>
> IFLA_BRIDGE_FLAGS
> IFLA_BRIDGE_MODE
> IFLA_BRIDGE_VLAN_INFO
> IFLA_BRIDGE_VLAN_INFO_LIST    // nested array of
>         IFLA_BRIDGE_VLAN_INFO_LIST_ENTRY
>
>
> Thanks,
> Roopa
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