mac80211: optimize station connection monitor

Calling mod_timer for every rx/tx packet can be quite expensive.
Instead of constantly updating the timer, we can simply let it run out
and check the timestamp of the last ACK or rx packet to re-arm it.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Link: https://lore.kernel.org/r/20200908123702.88454-9-nbd@nbd.name
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 22 insertions, 31 deletions

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 8e0f79cf4c02..50a9b9025725 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -2432,23 +2432,6 @@ static void ieee80211_set_disassoc(struct ieee80211_sub_if_data *sdata,
 	sdata->encrypt_headroom = IEEE80211_ENCRYPT_HEADROOM;
 }
 
-void ieee80211_sta_rx_notify(struct ieee80211_sub_if_data *sdata,
-			     struct ieee80211_hdr *hdr)
-{
-	/*
-	 * We can postpone the mgd.timer whenever receiving unicast frames
-	 * from AP because we know that the connection is working both ways
-	 * at that time. But multicast frames (and hence also beacons) must
-	 * be ignored here, because we need to trigger the timer during
-	 * data idle periods for sending the periodic probe request to the
-	 * AP we're connected to.
-	 */
-	if (is_multicast_ether_addr(hdr->addr1))
-		return;
-
-	ieee80211_sta_reset_conn_monitor(sdata);
-}
-
 static void ieee80211_reset_ap_probe(struct ieee80211_sub_if_data *sdata)
 {
 	struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
@@ -2521,21 +2504,13 @@ void ieee80211_sta_tx_notify(struct ieee80211_sub_if_data *sdata,
 {
 	ieee80211_sta_tx_wmm_ac_notify(sdata, hdr, tx_time);
 
-	if (!ieee80211_is_data(hdr->frame_control))
-	    return;
-
-	if (ieee80211_is_any_nullfunc(hdr->frame_control) &&
-	    sdata->u.mgd.probe_send_count > 0) {
-		if (ack)
-			ieee80211_sta_reset_conn_monitor(sdata);
-		else
-			sdata->u.mgd.nullfunc_failed = true;
-		ieee80211_queue_work(&sdata->local->hw, &sdata->work);
+	if (!ieee80211_is_any_nullfunc(hdr->frame_control) ||
+	    !sdata->u.mgd.probe_send_count)
 		return;
-	}
 
-	if (ack)
-		ieee80211_sta_reset_conn_monitor(sdata);
+	if (!ack)
+		sdata->u.mgd.nullfunc_failed = true;
+	ieee80211_queue_work(&sdata->local->hw, &sdata->work);
 }
 
 static void ieee80211_mlme_send_probe_req(struct ieee80211_sub_if_data *sdata,
@@ -3608,8 +3583,8 @@ static bool ieee80211_assoc_success(struct ieee80211_sub_if_data *sdata,
 	 * Start timer to probe the connection to the AP now.
 	 * Also start the timer that will detect beacon loss.
 	 */
-	ieee80211_sta_rx_notify(sdata, (struct ieee80211_hdr *)mgmt);
 	ieee80211_sta_reset_beacon_monitor(sdata);
+	ieee80211_sta_reset_conn_monitor(sdata);
 
 	ret = true;
  out:
@@ -4580,10 +4555,26 @@ static void ieee80211_sta_conn_mon_timer(struct timer_list *t)
 		from_timer(sdata, t, u.mgd.conn_mon_timer);
 	struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
 	struct ieee80211_local *local = sdata->local;
+	struct sta_info *sta;
+	unsigned long timeout;
 
 	if (sdata->vif.csa_active && !ifmgd->csa_waiting_bcn)
 		return;
 
+	sta = sta_info_get(sdata, ifmgd->bssid);
+	if (!sta)
+		return;
+
+	timeout = sta->status_stats.last_ack;
+	if (time_before(sta->status_stats.last_ack, sta->rx_stats.last_rx))
+		timeout = sta->rx_stats.last_rx;
+	timeout += IEEE80211_CONNECTION_IDLE_TIME;
+
+	if (time_is_before_jiffies(timeout)) {
+		mod_timer(&ifmgd->conn_mon_timer, round_jiffies_up(timeout));
+		return;
+	}
+
 	ieee80211_queue_work(&local->hw, &ifmgd->monitor_work);
 }