netdev - Re: [PATCH v2] 802.11n IBSS: wlan0 stops receiving packets due to aggregation after sender reboot

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Message-ID: <m37e4orkxr.fsf@t19.piap.pl>
Date:   Tue, 29 Oct 2019 09:54:24 +0100
From:   khalasa@...p.pl (Krzysztof Hałasa)
To:     Johannes Berg <johannes@...solutions.net>
Cc:     "David S. Miller" <davem@...emloft.net>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] 802.11n IBSS: wlan0 stops receiving packets due to aggregation after sender reboot

Johannes Berg <johannes@...solutions.net> writes:

> I think you just got very lucky (or unlucky) to have the same dialog
> token, because we start from 0

Right, it seems to be the case.

> - maybe we should initialize it to a
> random value to flush out such issues.

The problem I can see is that the dialog_tokens are 8-bit, way too small
to eliminate conflicts.

> Really what I think probably happened is that one of your stations lost
> the connection to the other, and didn't tell it about it in any way - so
> the other kept all the status alive.

You must have missed my previous mail - I simply rebooted that station,
and alternatively rmmoded/modprobed ath9k. But the problem originated in
a station going out of and back in range, in fact.

> I suspect to make all this work well we need to not only have the fixes
> I made recently to actually send and parse deauth frames, but also to
> even send an auth and reset the state when we receive that, so if we
> move out of range and even the deauth frame is lost, we can still reset
> properly.

That's one thing. The other is a station trying ADDBA for the first time
after boot (while the local station has seen it before that reboot).

> In any case, this is not the right approach - we need to handle the
> "lost connection" case better I suspect, but since you don't say what
> really happened I don't really know that that's what you're seeing.

I guess we need to identify "new connection" reliably. Otherwise,
the new connections are treated as old ones and it doesn't work.

Now how can it be fixed?
-- 
Krzysztof Halasa

ŁUKASIEWICZ Research Network
Industrial Research Institute for Automation and Measurements PIAP
Al. Jerozolimskie 202, 02-486 Warsaw, Poland