wifi: mac80211: only accumulate airtime deficit for active clients

When a client does not generate any local tx activity, accumulating airtime
deficit for the round-robin scheduler can be harmful. If this goes on for too
long, the deficit could grow quite large, which might cause unreasonable
initial latency once the client becomes active

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Link: https://lore.kernel.org/r/20220625212411.36675-7-nbd@nbd.name
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index 28ab55a072c60550964f3d7dc8a47d58d9bbbde0..c9852f71e8e15ac3ea2a2eec97bbc0efd469824d 100644 (file)
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -2046,6 +2046,7 @@ void ieee80211_sta_register_airtime(struct ieee80211_sta *pubsta, u8 tid,
        struct ieee80211_local *local = sta->sdata->local;
        u8 ac = ieee80211_ac_from_tid(tid);
        u32 airtime = 0;
+       u32 diff;
 
        if (sta->local->airtime_flags & AIRTIME_USE_TX)
                airtime += tx_airtime;
@@ -2055,7 +2056,11 @@ void ieee80211_sta_register_airtime(struct ieee80211_sta *pubsta, u8 tid,
        spin_lock_bh(&local->active_txq_lock[ac]);
        sta->airtime[ac].tx_airtime += tx_airtime;
        sta->airtime[ac].rx_airtime += rx_airtime;
-       sta->airtime[ac].deficit -= airtime;
+
+       diff = (u32)jiffies - sta->airtime[ac].last_active;
+       if (diff <= AIRTIME_ACTIVE_DURATION)
+               sta->airtime[ac].deficit -= airtime;
+
        spin_unlock_bh(&local->active_txq_lock[ac]);
 }
 EXPORT_SYMBOL(ieee80211_sta_register_airtime);