Re: [PATCH v6 6/6] cfg80211: remove channel_switch combination check

[Michal Kazior <michal.kazior@tieto.com>]

On 23 May 2014 10:53, Johannes Berg <johannes@sipsolutions.net> wrote:
> On Fri, 2014-05-23 at 09:04 +0200, Michal Kazior wrote:
>> On 22 May 2014 16:57, Johannes Berg <johannes@sipsolutions.net> wrote:
>> > On Thu, 2014-05-22 at 16:07 +0200, Michal Kazior wrote:
>> >> Make the driver responsible for making sure it is
>> >> capable of performing the switch. It might as well
>> >> accept a request but then disconnect an interface
>> >> if some requirements are not met.
>> >
>> > Care to elaborate? I'd really like to avoid this case as much as
>> > possible, so just mentioning here that it would be valid seems like a
>> > bad idea.
>>
>> Well, CSA isn't really visible to cfg80211 so you can't enforce anything now.
>>
>> Also since CSA requests are submitted one-by-one you already break
>> interface combinations and hope:
>>  a) userspace sends more CSA requests soon enough to make future
>> interface combination valid
>>  b) trust drivers deal with it either way
>>
>> So why bother?
>>
>> The most you can probably do is to prevent CSA requests from switching
>> to too many different channels but you can easily guarantee this in a
>> driver.
>
> Yeah, absolutely - it's just the fact that you're saying that it might
> accept but then disconnect ... that will make people feel OK about that,
> when it's really not all that desirable. Better to state that more
> explicitly that it should check before :)

I understand now. I'll try to emphasize this when I respin.


Michał