wifi: mac80211: switch airtime fairness back to deficit round-robin scheduling

This reverts commits 6a789ba679d652587532cec2a0e0274fda172f3b and
2433647bc8d983a543e7d31b41ca2de1c7e2c198.

The virtual time scheduler code has a number of issues:
- queues slowed down by hardware/firmware powersave handling were not properly
  handled.
- on ath10k in push-pull mode, tx queues that the driver tries to pull from
  were starved, causing excessive latency
- delay between tx enqueue and reported airtime use were causing excessively
  bursty tx behavior

The bursty behavior may also be present on the round-robin scheduler, but there
it is much easier to fix without introducing additional regressions

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Link: https://lore.kernel.org/r/20220625212411.36675-1-nbd@nbd.name
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 1 insertions, 34 deletions

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index b387f5f4fef0..fd6c4291c971 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -1581,38 +1581,6 @@ static void sta_apply_mesh_params(struct ieee80211_local *local,
 #endif
 }
 
-static void sta_apply_airtime_params(struct ieee80211_local *local,
-				     struct sta_info *sta,
-				     struct station_parameters *params)
-{
-	u8 ac;
-
-	for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {
-		struct airtime_sched_info *air_sched = &local->airtime[ac];
-		struct airtime_info *air_info = &sta->airtime[ac];
-		struct txq_info *txqi;
-		u8 tid;
-
-		spin_lock_bh(&air_sched->lock);
-		for (tid = 0; tid < IEEE80211_NUM_TIDS + 1; tid++) {
-			if (air_info->weight == params->airtime_weight ||
-			    !sta->sta.txq[tid] ||
-			    ac != ieee80211_ac_from_tid(tid))
-				continue;
-
-			airtime_weight_set(air_info, params->airtime_weight);
-
-			txqi = to_txq_info(sta->sta.txq[tid]);
-			if (RB_EMPTY_NODE(&txqi->schedule_order))
-				continue;
-
-			ieee80211_update_airtime_weight(local, air_sched,
-							0, true);
-		}
-		spin_unlock_bh(&air_sched->lock);
-	}
-}
-
 static int sta_apply_parameters(struct ieee80211_local *local,
 				struct sta_info *sta,
 				struct station_parameters *params)
@@ -1811,8 +1779,7 @@ static int sta_apply_parameters(struct ieee80211_local *local,
 		sta_apply_mesh_params(local, sta, params);
 
 	if (params->airtime_weight)
-		sta_apply_airtime_params(local, sta, params);
-
+		sta->airtime_weight = params->airtime_weight;
 
 	/* set the STA state after all sta info from usermode has been set */
 	if (test_sta_flag(sta, WLAN_STA_TDLS_PEER) ||