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authorFelix Fietkau <nbd@nbd.name>2020-08-08 19:28:07 +0200
committerFelix Fietkau <nbd@nbd.name>2020-08-09 14:01:49 +0200
commiteff8c76aa02275a7b325e0fa93cc349380299fde (patch)
treefd1c147853658b55ff7902edf541e4d9ae57095c
parente81e625ca375d6dc3c885ec870ec15757ac76d72 (diff)
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mac80211: fix spurious disconnect issues with disassoc_low_ack=1 (default)
mac80211 reports a packet loss event to user space when 50 consecutive packets were not acked. On a high throughput link with long aggregates and sudden link changes, this can trigger way too easily. Mitigate false positives by only triggering the event on a packet loss if no ACK was received for at least a second Signed-off-by: Felix Fietkau <nbd@nbd.name>
-rw-r--r--package/kernel/mac80211/patches/subsys/310-mac80211-reduce-packet-loss-event-false-positives.patch116
1 files changed, 116 insertions, 0 deletions
diff --git a/package/kernel/mac80211/patches/subsys/310-mac80211-reduce-packet-loss-event-false-positives.patch b/package/kernel/mac80211/patches/subsys/310-mac80211-reduce-packet-loss-event-false-positives.patch
new file mode 100644
index 0000000000..85094389a8
--- /dev/null
+++ b/package/kernel/mac80211/patches/subsys/310-mac80211-reduce-packet-loss-event-false-positives.patch
@@ -0,0 +1,116 @@
+From: Felix Fietkau <nbd@nbd.name>
+Date: Sat, 8 Aug 2020 19:20:02 +0200
+Subject: [PATCH] mac80211: reduce packet loss event false positives
+
+When running a large number of packets per second with a high data rate
+and long A-MPDUs, the packet loss threshold can be reached very quickly
+when the link conditions change. This frequently shows up as spurious
+disconnects.
+Mitigate false positives by using a similar logic for regular stations
+as the one being used for TDLS, though with a more aggressive timeout.
+Packet loss events are only reported if no ACK was received for a second.
+
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+
+--- a/net/mac80211/sta_info.h
++++ b/net/mac80211/sta_info.h
+@@ -522,7 +522,7 @@ struct ieee80211_sta_rx_stats {
+ * @status_stats.retry_failed: # of frames that failed after retry
+ * @status_stats.retry_count: # of retries attempted
+ * @status_stats.lost_packets: # of lost packets
+- * @status_stats.last_tdls_pkt_time: timestamp of last TDLS packet
++ * @status_stats.last_pkt_time: timestamp of last ACKed packet
+ * @status_stats.msdu_retries: # of MSDU retries
+ * @status_stats.msdu_failed: # of failed MSDUs
+ * @status_stats.last_ack: last ack timestamp (jiffies)
+@@ -595,7 +595,7 @@ struct sta_info {
+ unsigned long filtered;
+ unsigned long retry_failed, retry_count;
+ unsigned int lost_packets;
+- unsigned long last_tdls_pkt_time;
++ unsigned long last_pkt_time;
+ u64 msdu_retries[IEEE80211_NUM_TIDS + 1];
+ u64 msdu_failed[IEEE80211_NUM_TIDS + 1];
+ unsigned long last_ack;
+--- a/net/mac80211/status.c
++++ b/net/mac80211/status.c
+@@ -749,12 +749,16 @@ static void ieee80211_report_used_skb(st
+ * - current throughput (higher value for higher tpt)?
+ */
+ #define STA_LOST_PKT_THRESHOLD 50
++#define STA_LOST_PKT_TIME HZ /* 1 sec since last ACK */
+ #define STA_LOST_TDLS_PKT_THRESHOLD 10
+ #define STA_LOST_TDLS_PKT_TIME (10*HZ) /* 10secs since last ACK */
+
+ static void ieee80211_lost_packet(struct sta_info *sta,
+ struct ieee80211_tx_info *info)
+ {
++ unsigned long pkt_time = STA_LOST_PKT_TIME;
++ unsigned int pkt_thr = STA_LOST_PKT_THRESHOLD;
++
+ /* If driver relies on its own algorithm for station kickout, skip
+ * mac80211 packet loss mechanism.
+ */
+@@ -767,21 +771,20 @@ static void ieee80211_lost_packet(struct
+ return;
+
+ sta->status_stats.lost_packets++;
+- if (!sta->sta.tdls &&
+- sta->status_stats.lost_packets < STA_LOST_PKT_THRESHOLD)
+- return;
++ if (sta->sta.tdls) {
++ pkt_time = STA_LOST_TDLS_PKT_TIME;
++ pkt_thr = STA_LOST_PKT_THRESHOLD;
++ }
+
+ /*
+ * If we're in TDLS mode, make sure that all STA_LOST_TDLS_PKT_THRESHOLD
+ * of the last packets were lost, and that no ACK was received in the
+ * last STA_LOST_TDLS_PKT_TIME ms, before triggering the CQM packet-loss
+ * mechanism.
++ * For non-TDLS, use STA_LOST_PKT_THRESHOLD and STA_LOST_PKT_TIME
+ */
+- if (sta->sta.tdls &&
+- (sta->status_stats.lost_packets < STA_LOST_TDLS_PKT_THRESHOLD ||
+- time_before(jiffies,
+- sta->status_stats.last_tdls_pkt_time +
+- STA_LOST_TDLS_PKT_TIME)))
++ if (sta->status_stats.lost_packets < pkt_thr ||
++ !time_after(jiffies, sta->status_stats.last_pkt_time + pkt_time))
+ return;
+
+ cfg80211_cqm_pktloss_notify(sta->sdata->dev, sta->sta.addr,
+@@ -1034,9 +1037,7 @@ static void __ieee80211_tx_status(struct
+ sta->status_stats.lost_packets = 0;
+
+ /* Track when last TDLS packet was ACKed */
+- if (test_sta_flag(sta, WLAN_STA_TDLS_PEER_AUTH))
+- sta->status_stats.last_tdls_pkt_time =
+- jiffies;
++ sta->status_stats.last_pkt_time = jiffies;
+ } else if (noack_success) {
+ /* nothing to do here, do not account as lost */
+ } else {
+@@ -1169,9 +1170,8 @@ void ieee80211_tx_status_ext(struct ieee
+ if (sta->status_stats.lost_packets)
+ sta->status_stats.lost_packets = 0;
+
+- /* Track when last TDLS packet was ACKed */
+- if (test_sta_flag(sta, WLAN_STA_TDLS_PEER_AUTH))
+- sta->status_stats.last_tdls_pkt_time = jiffies;
++ /* Track when last packet was ACKed */
++ sta->status_stats.last_pkt_time = jiffies;
+ } else if (test_sta_flag(sta, WLAN_STA_PS_STA)) {
+ return;
+ } else if (noack_success) {
+@@ -1260,8 +1260,7 @@ void ieee80211_tx_status_8023(struct iee
+ if (sta->status_stats.lost_packets)
+ sta->status_stats.lost_packets = 0;
+
+- if (test_sta_flag(sta, WLAN_STA_TDLS_PEER_AUTH))
+- sta->status_stats.last_tdls_pkt_time = jiffies;
++ sta->status_stats.last_pkt_time = jiffies;
+ } else {
+ ieee80211_lost_packet(sta, info);
+ }