[PATCH 10/27] wifi: mac80211: isolate driver from inactive links

[Wen Gong]

On 6/21/2023 3:55 PM, Wen Gong wrote:
> On 6/15/2023 3:56 PM, Johannes Berg wrote:
>> On Thu, 2023-06-15 at 10:26 +0800, Wen Gong wrote:
>>> On 6/15/2023 2:32 AM, Johannes Berg wrote:
>>>> On Wed, 2023-05-24 at 15:41 +0800, Wen Gong wrote:
>>>>> May I add a new ops in struct ieee80211_ops? like this:
>>>>>
>>>>> u16 active_links(struct ieee80211_hw *hw, struct ieee80211_vif 
>>>>> vif, u16
>>>>> new_links)"
>>>>>
>>>>> then ieee80211_set_vif_links_bitmaps() call the ops to get the 
>>>>> links for
>>>>> station and set the sdata->vif.active_links with the return value 
>>>>> from
>>>>> lower driver,
>>>>> it means lower driver will dynamic select the links count at this 
>>>>> moment.
>>>>>
>>>>> If lower driver not register ops active_links, then keep current 
>>>>> logic.
>>>>>
>>>> I guess you can can send patches for whatever you want :)
>>>>
>>>> But I have no idea what you're trying to do? Why would you need to 
>>>> have
>>>> a callback?
>>> Currently driver could use ieee80211_set_active_links_async() to active
>>> links after connection completed.
>> Right.
>>
>>> But I would like to allow driver to select active links in a early 
>>> time,
>>> it will be more convenient for driver.
>> How so? All you have to do is look for the connection becoming
>> authorized (e.g. sta state for the AP moving to authorized) and then
>> selecting the links you want. We've already been working on that, it's
>> really easy?
> It is more complex for ath12k drivers.
>>
>> On the flip-side, it would be highly inconvenient for mac80211 to try to
>> enable more links *during* the association process, and actually it's
>> not even allowed by spec until the 4-way-HS finishes. So the earliest
>> possible time is pretty much when you can just do it in the driver as I
>> just described.
>>
>>>> Was this for link selection in the driver? We should have a patch
>>>> somewhere that adds a BSS_CHANGE flag for when the valid links change,
>>>> so the driver can select others.
>>>>
>>>> johannes
>>> Yes, it is for link selection in driver at a early time before
>>> connection completed.
>> This is not really allowed ... At least not without also finding ways to
>> really transmit the 802.1X and 4-way-HS only on the right link, etc.
> Yes, I also found this in section "2.7.6.1 General"  of IEEE P802.11be:
> "For MLO, if RSNA has not been established, each message of the 4-way 
> handshake shall be sent on
> the same link used by the latest exchange of successful 
> (Re)Association Request/Response frames."
>
> For ath12k drivers, only the primary link(the link used by the latest 
> exchange of successful (Re)Association
> Request/Response frames) is active before key installed, so the 802.1X 
> and 4-way-HS will always sent on
> the primary link, so it will meet the rule above of section "2.7.6.1 
> General".
>
> It means: lower driver will ensure the rule when it implmented the 
> active_links callback such as ath12k.
Johannes, do you have more comments for my answer above?😁
>>> Could you tell detail about how the BSS_CHANGE flag works?😁
>> The work isn't complete yet, but basically it just calls the callback
>> whenever the valid_links changed, say by link-reconfiguration.
>>
>> johannes