Re: [RFC v3 6/8] wifi: mac80211: extend ifcomb check functions for multi-radio

[Felix Fietkau <nbd@nbd.name>]

On 07.06.24 12:53, Karthikeyan Periyasamy wrote:
> 
> 
> On 6/7/2024 3:52 PM, Felix Fietkau wrote:
>> On 07.06.24 12:07, Karthikeyan Periyasamy wrote:
>>>
>>>
>>> On 6/6/2024 11:37 PM, Felix Fietkau wrote:
>>>> Add support for counting global and per-radio max/current number of
>>>> channels, as well as checking radio-specific interface combinations.
>>>>
>>>> Signed-off-by: Felix Fietkau <nbd@nbd.name>
>>>> ---
>>>>   net/mac80211/cfg.c         |   7 +-
>>>>   net/mac80211/chan.c        |  17 +++--
>>>>   net/mac80211/ibss.c        |   2 +-
>>>>   net/mac80211/ieee80211_i.h |   6 +-
>>>>   net/mac80211/iface.c       |   2 +-
>>>>   net/mac80211/util.c        | 131 
>>>> +++++++++++++++++++++++++++-----------
>>>>   6 files changed, 116 insertions(+), 49 deletions(-)
>>>>
>>>> diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
>>>> index 62119e957cd8..950b7b72f0b8 100644
>>>> --- a/net/mac80211/cfg.c
>>>> +++ b/net/mac80211/cfg.c
>>>> @@ -263,7 +263,7 @@ static int ieee80211_start_p2p_device(struct 
>>>> wiphy *wiphy,
>>>>       lockdep_assert_wiphy(sdata->local->hw.wiphy);
>>>> -    ret = ieee80211_check_combinations(sdata, NULL, 0, 0);
>>>> +    ret = ieee80211_check_combinations(sdata, NULL, 0, 0, -1);
>>>>       if (ret < 0)
>>>>           return ret;
>>>> @@ -285,7 +285,7 @@ static int ieee80211_start_nan(struct wiphy *wiphy,
>>>>       lockdep_assert_wiphy(sdata->local->hw.wiphy);
>>>> -    ret = ieee80211_check_combinations(sdata, NULL, 0, 0);
>>>> +    ret = ieee80211_check_combinations(sdata, NULL, 0, 0, -1);
>>>>       if (ret < 0)
>>>>           return ret;
>>>> @@ -4001,7 +4001,7 @@ __ieee80211_channel_switch(struct wiphy *wiphy, 
>>>> struct net_device *dev,
>>>>           goto out;
>>>>       /* if reservation is invalid then this will fail */
>>>> -    err = ieee80211_check_combinations(sdata, NULL, chanctx->mode, 0);
>>>> +    err = ieee80211_check_combinations(sdata, NULL, chanctx->mode, 
>>>> 0, -1);
>>>
>>> Once we reach the global limit, all the -1 passing caller get fail
>>> becuase the iface check param (existing and new) is validated against
>>> the global limit. since global limt as a sort of union of all per-radio
>>> limits.
>>>
>>> Ex:
>>> Global iface = 6 (Radio iface 2GHz:4, 5GHz:4, 6GHz:6)
>>>
>>>
>>> So far 6 iface created (Radio iface 2GHz:2, 5GHz:3, 6GHz:1)
>>>
>>> In this case, new iface creation get fail because caller uses
>>> ieee80211_check_combinations() with -1 as radio idx, so it checked
>>> against global limit
>> 
>> Use the sum of the number of interfaces from each radio instead of the 
>> maximum.
> 
> Oh, then legacy user have misconception of the global interfaces
> advertised and try to fail for the allowed limits.

Sure, but that might be an issue either way until user space is updated 
and users start looking at the per-radio ifcomb data.
The global data is simply not enough to describe the details of the 
radio split.

- Felix