Messages in this thread Patch in this message | | | Date | Tue, 10 Jan 2023 12:35:04 +0000 | From | Bryan O'Donoghue <> | Subject | ieee80211_handle_wake_tx_queue and dynamic ps regression |
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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 tried this as a fix
--- a/net/mac80211/mlme.c +++ b/net/mac80211/mlme.c @@ -2245,15 +2245,15 @@ void ieee80211_dynamic_ps_disable_work(struct work_struct *work) container_of(work, struct ieee80211_local, dynamic_ps_disable_work);
- if (local->hw.conf.flags & IEEE80211_CONF_PS) { - local->hw.conf.flags &= ~IEEE80211_CONF_PS; - ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS); - } - ieee80211_wake_queues_by_reason(&local->hw, IEEE80211_MAX_QUEUE_MAP, IEEE80211_QUEUE_STOP_REASON_PS, false); + + if (local->hw.conf.flags & IEEE80211_CONF_PS) { + local->hw.conf.flags &= ~IEEE80211_CONF_PS; + ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS); + } }
but it only "slightly improves" the situation, the fundamental race condition is still there.
Suggest reverting this change and trying again. --- bod
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