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Date: Wed, 25 Feb 2015 12:22:35 -0800
Message-ID: <CAJ-VmokL7-hL_KNx4=M6s8H6gYuKV8KaeA61qto_R=1fe8510g@mail.gmail.com> (sfid-20150225_212239_769993_E46E7766)
Subject: Re: [ath9k-devel] AR9462 problems connecting again..
From: Adrian Chadd <adrian@freebsd.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jouni Malinen <j@w1.fi>, Felix Fietkau <nbd@openwrt.org>,
	=?UTF-8?B?VGhvbWFzIEjDvGhu?= <thomas@net.t-labs.tu-berlin.de>,
	"Luis R. Rodriguez" <mcgrof@do-not-panic.com>,
	Andrew McGregor <andrewmcgr@gmail.com>,
	linux-wireless <linux-wireless@vger.kernel.org>,
	"ath9k-devel@lists.ath9k.org" <ath9k-devel@lists.ath9k.org>,
	Kalle Valo <kvalo@codeaurora.org>
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Sender: linux-wireless-owner@vger.kernel.org

On 25 February 2015 at 10:14, Linus Torvalds
<torvalds@linux-foundation.org> wrote:


> While I realize that people may disagree about the exact details of
> how to fix this in the long run, may I suggest that in the meantime we
> at least get the two workaround patches applied?
>
> I'm talking about the two from Jouni - the "don't encrypt EAPOL
> frames" one, and the one-liner that makes all EAPOL frames go at the
> lowest data rate.
>
> Even if "lowest data rate" is ridiculously low, and even if that might
> disturb other things going on on the same channel at the same time,
> those authentication packets shouldn't be so common as to be a
> problem.  No?
>
> Jouni has a few packet dumps for me, and he's stumped as to what
> exactly is going on, but those two patches (well, the one-liner "low
> data rate EAPOL" in particular, it seems) do seem to make my
> connections go through reliably.
>
> And it seems that other drivers already are working around the EAPOL
> issue in similar ways, judging by the comments about iwlwifi.

[snip]

> So I'm sure I can improve reception of my laptop, but that's not the
> point. The point is that bad wireless networks aren't so unusual, and
> right now things clearly don't work as well as they could.
>
> Does anybody hate Jouni's two patches *so* much that they can
> articulate *why* it would be wrong to apply them as interim patches?
> And if so, do you have better patches for me to try? Because if not..

I agree with you. I think you should just have EAPOL frames go out at
the lowest rate for now and then worry about experimenting with more
interesting ways to make EAPOL / DHCP frames cheaper. It fixes a lot
of problems in noisy areas. That hack was hiding around in various
commercial drivers I've seen, and it's been in FreeBSD for a while.

Same with DHCP traffic too - it's the second set of data frames that
the rate control code sees, and it's the primary reason I dropped the
initial sample rate down in FreeBSD so the DHCP exchange would have a
better chance of succeeding after association.


-adrian