mac80211: reduce packet loss notifications under load

During strong signal fluctuations under high throughput, few consecutive
failed A-MPDU transmissions can easily trigger packet loss notification,
and thus (in AP mode) client disconnection.

Reduce the number of false positives by checking the A-MPDU status flag
and treating a failed A-MPDU as a single packet.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/mac80211/status.c b/net/mac80211/status.c
index e6e574a..bfa5326 100644 (file)
--- a/net/mac80211/status.c
+++ b/net/mac80211/status.c
@@ -542,6 +542,23 @@ static void ieee80211_tx_latency_end_msrmnt(struct ieee80211_local *local,
  */
 #define STA_LOST_PKT_THRESHOLD 50
 
+static void ieee80211_lost_packet(struct sta_info *sta, struct sk_buff *skb)
+{
+       struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
+
+       /* This packet was aggregated but doesn't carry status info */
+       if ((info->flags & IEEE80211_TX_CTL_AMPDU) &&
+           !(info->flags & IEEE80211_TX_STAT_AMPDU))
+               return;
+
+       if (++sta->lost_packets < STA_LOST_PKT_THRESHOLD)
+               return;
+
+       cfg80211_cqm_pktloss_notify(sta->sdata->dev, sta->sta.addr,
+                                   sta->lost_packets, GFP_ATOMIC);
+       sta->lost_packets = 0;
+}
+
 void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb)
 {
        struct sk_buff *skb2;
@@ -680,12 +697,8 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb)
                        if (info->flags & IEEE80211_TX_STAT_ACK) {
                                if (sta->lost_packets)
                                        sta->lost_packets = 0;
-                       } else if (++sta->lost_packets >= STA_LOST_PKT_THRESHOLD) {
-                               cfg80211_cqm_pktloss_notify(sta->sdata->dev,
-                                                           sta->sta.addr,
-                                                           sta->lost_packets,
-                                                           GFP_ATOMIC);
-                               sta->lost_packets = 0;
+                       } else {
+                               ieee80211_lost_packet(sta, skb);
                        }
                }