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From: =?utf-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= <toke@toke.dk>
To: Felix Fietkau <nbd@nbd.name>
Cc: Kalle Valo <kvalo@codeaurora.org>, linux-wireless@vger.kernel.org
Subject: Re: [PATCH] ath9k: clean up and fix ath_tx_count_airtime
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Date: Sun, 12 Feb 2017 19:13:41 +0100
In-Reply-To: <e8a1dd5f-79a2-28b4-6cc7-fc1b28a6f327@nbd.name> (Felix Fietkau's
        message of "Sun, 12 Feb 2017 17:40:27 +0100")
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Felix Fietkau <nbd@nbd.name> writes:

> On 2017-02-12 17:36, Toke H=C3=B8iland-J=C3=B8rgensen wrote:
>> Felix Fietkau <nbd@nbd.name> writes:
>>=20
>>> On 2017-02-12 17:28, Kalle Valo wrote:
>>>> Felix Fietkau <nbd@nbd.name> writes:
>>>>=20
>>>>> On 2017-02-12 16:22, Toke H=C3=B8iland-J=C3=B8rgensen wrote:
>>>>>> Felix Fietkau <nbd@nbd.name> writes:
>>>>>>=20
>>>>>>> ath_tx_count_airtime is doing a lot of unnecessary work:
>>>>>>>
>>>>>>> - Redundant station lookup
>>>>>>> - Redundant rcu_read_lock/unlock
>>>>>>> - Useless memcpy of bf->rates
>>>>>>> - Useless NULL check of bf->bf_mpdu
>>>>>>> - Redundant lookup of the skb tid
>>>>>>>
>>>>>>> Additionally, it tries to look up the mac80211 queue index from the=
 txq,
>>>>>>> which fails if the frame was delivered via the power save queue.
>>>>=20
>>>> What does this mean in practise, what's the user level impact?
>>>>=20
>>>>>>> This patch fixes all of these issues by passing down the right set =
of
>>>>>>> pointers instead of doing extra work
>>>>>>>
>>>>>>> Cc: stable@vger.kernel.org
>>>>>>> Fixes: 63fefa050477 ("ath9k: Introduce airtime fairness scheduling
>>>>>>> between stations")
>>>>>>> Signed-off-by: Felix Fietkau <nbd@nbd.name>
>>>>>>=20
>>>>>> Not sure if there's anything for stable to do with this; don't think=
 the
>>>>>> airtime fairness code has gone into a release yet? Otherwise:
>>>>>>=20
>>>>>> Acked-by: Toke H=C3=B8iland-J=C3=B8rgensen <toke@toke.dk>
>>>>>
>>>>> I added this, because I'm not sure this patch will make it to 4.10 in
>>>>> time, since we're really close to a release. I assume this patch will
>>>>> probably go into 4.11.
>>>>=20
>>>> Yeah, to try to get a patch to 4.10 at this point needs to be a really
>>>> high profile regression. That is if Linus doesn't release 4.10 today, =
of
>>>> course.
>>> The symptoms are kernel crashes at least when operating in AP mode.
>>> It's pretty severe, so getting it into 4.10 would be preferable.
>>=20
>> I'm confused now. Wasn't the airtime fairness patch queued for 4.11?
> I'll check again, maybe I got the git-describe output wrong.

$ git describe --contains 63fefa050477
wireless-drivers-next-for-davem-2017-01-02~2^2~14

So I think we're good as long as this gets into the 4.11 cycle :)

-Toke