From: Alexander Wetzel <alexander@wetzel-home.de>
To: Bryan O'Donoghue <bryan.odonoghue@linaro.org>,
linux-kernel@vger.kernel.org, johannes.berg@intel.com,
Kalle Valo <kvalo@codeaurora.org>,
linux-wireless@vger.kernel.org
Subject: Re: ieee80211_handle_wake_tx_queue and dynamic ps regression
Date: Tue, 10 Jan 2023 16:23:21 +0100 [thread overview]
Message-ID: <205fb221-f7ad-8f03-2c16-54dcbf5ecaf9@wetzel-home.de> (raw)
In-Reply-To: <cf5e9339-2511-1135-71da-a8342b264414@linaro.org>
On 10.01.23 15:47, Bryan O'Donoghue wrote:
> On 10/01/2023 12:44, Bryan O'Donoghue wrote:
>> + linux-wireless
>> On 10/01/2023 12:35, Bryan O'Donoghue wrote:
>>> commit a790cc3a4fad75048295571a350b95b87e022a5a
>>> (wake_tx_queue-broken-23-08-01)
>>> Author: Alexander Wetzel <alexander@wetzel-home.de>
>>> Date: Sun Oct 9 18:30:39 2022 +0200
>>>
>>> wifi: mac80211: add wake_tx_queue callback to drivers
>>>
>>> is causing a regression with
>>>
>>> - CONF_PS = 1
>>> - CONF_DYNAMIC_PS = 0
>>> - ieee80211_handle_wake_tx_queue
>>>
>>> In this case we get stuck in a loop similar to this
>>>
>>> // IEEE80211_CONF_CHANGE_PS
>>> [ 17.255480] wcn36xx: wcn36xx_change_ps/312 enable
>>> [ 18.088835] ieee80211_tx_h_dynamic_ps/263 setting
>>> IEEE80211_QUEUE_STOP_REASON_PS
>>> [ 18.088906] ieee80211_handle_wake_tx_queue/334 entry
>>> [ 18.091505] ieee80211_dynamic_ps_disable_work/2250 calling
>>> ieee80211_hw_config()
>>> [ 18.095370] ieee80211_handle_wake_tx_queue/338 wake_tx_push_queue
>>>
>>> // IEEE80211_CONF_CHANGE_PS
>>> [ 18.102625] wcn36xx: wcn36xx_change_ps/312 disable
>>> [ 18.107643] wake_tx_push_queue/303 entry
>>>
>>> // txq is stopped here reason == IEEE80211_QUEUE_STOP_REASON_PS
>>> [ 18.107654] wake_tx_push_queue/311 q_stopped bitmask 0x00000002
>>> IEEE80211_QUEUE_STOP_REASON_PS true
>>> [ 18.107661] wake_tx_push_queue/324 exit
>>> [ 18.107667] ieee80211_handle_wake_tx_queue/342 exit
>>> [ 18.115560] ieee80211_handle_wake_tx_queue/334 entry
>>> [ 18.139937] ieee80211_handle_wake_tx_queue/338 wake_tx_push_queue
>>> [ 18.145163] wake_tx_push_queue/303 entry
>>> [ 18.150016] ieee80211_dynamic_ps_disable_work/2252 completed
>>> ieee80211_hw_config()
>>>
>>> // now we unset IEEE80211_QUEUE_STOP_REASON_PS but too late
>>> [ 18.151145] wake_tx_push_queue/311 q_stopped bitmask 0x00000002
>>> IEEE80211_QUEUE_STOP_REASON_PS true
>>> [ 18.155263] ieee80211_dynamic_ps_disable_work/2254 clearing
>>> IEEE80211_QUEUE_STOP_REASON_PS
>>> [ 18.162531] wake_tx_push_queue/324 exit
>>> [ 18.162548] ieee80211_handle_wake_tx_queue/342 exit
>>> [ 18.183639] ieee80211_dynamic_ps_disable_work/2259 cleared
>>> IEEE80211_QUEUE_STOP_REASON_PS
>>>
>>> // IEEE80211_CONF_CHANGE_PS runs again
>>> [ 18.215487] wcn36xx: wcn36xx_change_ps/312 enable
>>>
>>> We get stuck in that loop. Packets getting transmitted is a rare
>>> event, most are dropped.
>
I'll need some time digest that... I report back once I get it.
> BTW I considered implementing a wcn36xx specific wake_tx callback -
> which maybe should be done anyway.
>
> I _don't_ see other drivers checking for q_stopped &
> IEEE80211_QUEUE_STOP_REASON_PS
>
> Should they be ?
>
No, they should not.
My take is, that this is a bug in mac80211. I submitted patches to
fixing that, they have just been accepted:
https://patchwork.kernel.org/project/linux-wireless/patch/20221230121850.218810-1-alexander@wetzel-home.de/
and
https://patchwork.kernel.org/project/linux-wireless/patch/20230106223141.98696-1-alexander@wetzel-home.de/
Can you test if these also help here?
> If they should check IEEE80211_QUEUE_STOP_REASON_PS, then right now,
> they don't. If they shouldn't check IEEE80211_QUEUE_STOP_REASON_PS then
> neither should the generic replacement ieee80211_handle_wake_tx_queue()
>
> ---
> bod
next prev parent reply other threads:[~2023-01-10 15:24 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <19015168-c747-17b7-f0ae-9d2ee27d221c@linaro.org>
2023-01-10 12:44 ` ieee80211_handle_wake_tx_queue and dynamic ps regression Bryan O'Donoghue
2023-01-10 14:47 ` Bryan O'Donoghue
2023-01-10 15:23 ` Alexander Wetzel [this message]
2023-01-10 15:43 ` Alexander Wetzel
2023-01-10 19:35 ` Bryan O'Donoghue
2023-01-13 12:17 ` Linux kernel regression tracking (#update)
2023-01-10 16:06 ` Bryan O'Donoghue
2023-01-10 13:08 ` Linux kernel regression tracking (Thorsten Leemhuis)
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