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Subject: Re: [PATCH] mac80211: Send deauth to STA's upon AP stop
To:     Johannes Berg <johannes@sipsolutions.net>,
        Ben Greear <greearb@candelatech.com>
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From:   Shay Bar <shay.bar@celeno.com>
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On 25/06/2020 12:51, Johannes Berg wrote:
> External Email
>
>
> On Sun, 2020-06-21 at 10:12 +0000, Shay Bar wrote:
>> Hi Johannes and Ben,
>>
>> To conclude this thread, hostapd doesn=E2=80=99t send any deauth/disasso=
c
>> upon AP stop (when hostapd is killed _or_ when "ifconfig down" the
>> AP interface).
>
> Right. I'm sort of suggesting you just shouldn't be doing this, and it
> doesn't seem like most people actually do, otherwise we'd have seen this
> issue before?
>
I shouldn't kill hostapd? Isn't this a very basic action?
What is the alternative for stopping the AP?

>> This is causing a situation where stations keep sending unicast frames
>> to a down AP interface as it doesn=E2=80=99t know it's gone down.
>> I tried your suggestion and sent 1 deauth/disassoc as broadcast
>> (instead of unicast to each STA), but some stations (e.g. Samsung S8)
>> Ignore this broadcast (while it will not ignore unicast deauth/disassoc)=
.
>> Although not indicated in the standard, I think it's better to let STA
>> Know AP gone down by sending this unicast deauth to each STA
>> (as this patch does).
>
> I'm not really sure. That's a _lot_ of frames and potentially quite a
> long time. In the patch, as written, I'm not even convinced you can be
> sure that they will all make it out to the air?
I agree, but what's the alternative?

Thanks,
Shay
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