wifi: mac80211: cleanup airtime arithmetic with ieee80211_sta_keep_active()

Prefer native jiffies-wide 'unsigned long' for the 'last_active' field of
'struct airtime_info' and introduce 'ieee80211_sta_keep_active()' for airtime
check in 'ieee80211_txq_keep_active()' and 'ieee80211_sta_register_airtime()'.
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Reviewed-by: Toke Høiland-Jørgensen <toke@toke.dk>
Link: https://msgid.link/20231206060935.612241-1-dmantipov@yandex.ruSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/ieee80211_i.h

@@ -92,11 +92,14 @@ enum ieee80211_status_data {
 	IEEE80211_STATUS_SUBDATA_MASK	= 0xff0,
 };
 
-/*
- * Keep a station's queues on the active list for deficit accounting purposes
- * if it was active or queued during the last 100ms
- */
-#define AIRTIME_ACTIVE_DURATION (HZ / 10)
+static inline bool
+ieee80211_sta_keep_active(struct sta_info *sta, u8 ac)
+{
+	/* Keep a station's queues on the active list for deficit accounting
+	 * purposes if it was active or queued during the last 100ms.
+	 */
+	return time_before_eq(jiffies, sta->airtime[ac].last_active + HZ / 10);
+}
 
 struct ieee80211_bss {
 	u32 device_ts_beacon, device_ts_presp;

net/mac80211/sta_info.c

@@ -2268,7 +2268,6 @@ 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;
@@ -2279,8 +2278,7 @@ void ieee80211_sta_register_airtime(struct ieee80211_sta *pubsta, u8 tid,
 	sta->airtime[ac].tx_airtime += tx_airtime;
 	sta->airtime[ac].rx_airtime += rx_airtime;
 
-	diff = (u32)jiffies - sta->airtime[ac].last_active;
-	if (diff <= AIRTIME_ACTIVE_DURATION)
+	if (ieee80211_sta_keep_active(sta, ac))
 		sta->airtime[ac].deficit -= airtime;
 
 	spin_unlock_bh(&local->active_txq_lock[ac]);

net/mac80211/sta_info.h

@@ -138,7 +138,7 @@ enum ieee80211_agg_stop_reason {
 struct airtime_info {
 	u64 rx_airtime;
 	u64 tx_airtime;
-	u32 last_active;
+	unsigned long last_active;
 	s32 deficit;
 	atomic_t aql_tx_pending; /* Estimated airtime for frames pending */
 	u32 aql_limit_low;

net/mac80211/tx.c

@@ -4013,14 +4013,13 @@ ieee80211_txq_set_active(struct txq_info *txqi)
 		return;
 
 	sta = container_of(txqi->txq.sta, struct sta_info, sta);
-	sta->airtime[txqi->txq.ac].last_active = (u32)jiffies;
+	sta->airtime[txqi->txq.ac].last_active = jiffies;
 }
 
 static bool
 ieee80211_txq_keep_active(struct txq_info *txqi)
 {
 	struct sta_info *sta;
-	u32 diff;
 
 	if (!txqi->txq.sta)
 		return false;
@@ -4029,9 +4028,7 @@ ieee80211_txq_keep_active(struct txq_info *txqi)
 	if (ieee80211_sta_deficit(sta, txqi->txq.ac) >= 0)
 		return false;
 
-	diff = (u32)jiffies - sta->airtime[txqi->txq.ac].last_active;
-
-	return diff <= AIRTIME_ACTIVE_DURATION;
+	return ieee80211_sta_keep_active(sta, txqi->txq.ac);
 }
 
 struct ieee80211_txq *ieee80211_next_txq(struct ieee80211_hw *hw, u8 ac)