Re: [PATCH] ath9k: clean up and fix ath_tx_count_airtime

[Felix Fietkau <nbd@nbd.name>]

On 2017-02-12 17:28, Kalle Valo wrote:
> Felix Fietkau <nbd@nbd.name> writes:
> 
>> On 2017-02-12 16:22, Toke Høiland-Jørgensen wrote:
>>> Felix Fietkau <nbd@nbd.name> writes:
>>> 
>>>> 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.
> 
> What does this mean in practise, what's the user level impact?
> 
>>>> 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>
>>> 
>>> 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:
>>> 
>>> Acked-by: Toke Høiland-Jørgensen <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.
> 
> 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.

- Felix