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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>
Link: https://lore.kernel.org/r/20200808172542.41628-1-nbd@nbd.name
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Felix Fietkau 2020-08-08 19:25:42 +02:00 committed by Johannes Berg
parent 47caf685a6
commit 47df8e059b
2 changed files with 17 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
net/mac80211/sta_info.h
View File

@ -524,7 +524,7 @@ 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)
@ -597,7 +597,7 @@ 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;

31
net/mac80211/status.c
View File

@ -755,12 +755,16 @@ static void ieee80211_report_used_skb(struct ieee80211_local *local,
* - 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.
*/
@ -773,21 +777,20 @@ static void ieee80211_lost_packet(struct sta_info *sta,
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,
@ -1033,9 +1036,7 @@ static void __ieee80211_tx_status(struct ieee80211_hw *hw,
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 {
@ -1172,9 +1173,8 @@ void ieee80211_tx_status_ext(struct ieee80211_hw *hw,
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) {
@ -1263,8 +1263,7 @@ void ieee80211_tx_status_8023(struct ieee80211_hw *hw,
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);
}