[Make-wifi-fast] [PATCH RFC v4 3/4] mac80211: Add airtime accounting and scheduling to TXQs

Toke Høiland-Jørgensen toke at toke.dk
Wed Oct 3 04:41:16 EDT 2018

Rajkumar Manoharan <rmanohar at codeaurora.org> writes:

> On 2018-10-02 16:07, Rajkumar Manoharan wrote:
>> On 2018-10-02 12:00, Toke Høiland-Jørgensen wrote:
>>> Rajkumar Manoharan <rmanohar at codeaurora.org> writes:
>>>> I noticed a race condition b/w sta cleanup and kick_airtime tasklet.
>>>>>> How do you plan to exit kick_airtime gracefully during sta_cleanup?
>>>>> Ah, right, there's a lot of stuff going on before we get to 
>>>>> purge_txq.
>>>>> Hmm, I guess we should either make sure we remove the station from
>>>>> active_txqs earlier in the sta cleanup process, or maybe it'd enough 
>>>>> to
>>>>> just check the removed flag in the tasklet?
>>>>> Does the below patch fix the issue?
>>>> No. Attaching backtrace. Any clue?
>>> Ah, that's my bad. Just having a 'continue' there can make the 
>>> function
>>> loop forever. Oops. Try something like this instead?
>> But 'continue' also used in other places. Will give a try but I think 
>> that
>> calling drv_wake_tx_queue within iteration is dangerous as it alters
>> the list. no?
> How about below change? Just schedule first txq and remaining will be
> scheduled later by driver upon tx-compl.

Your mail client seems to be mangling the patch somewhat, but I think I
see what your intention is. And yeah, just waking a single TXQ and
letting TX-completion do the rest is a good idea; will fold that into
the next version :)


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