policy: add min_snr_kick_delay

Currently the min_snr option will result in kicking clients the first
time their SNR dips below.

This might not be desirable, as drivers (notably ath10k) sometimes
report a much lower RSSI for a short timeframe after returning to
sensible values. Also, a device might be in the process of roaming just
to be kicked before.

Add the min_snr_kick_delay option. A client will be kicked after this
timeframe when it's SNR is below the min_snr threshold value over the
complete timeframe.

Signed-off-by: David Bauer <mail@david-bauer.net>

main.c

@@ -103,6 +103,8 @@ void usteer_init_defaults(void)
 	config.roam_scan_interval = 10 * 1000;
 	config.roam_trigger_interval = 60 * 1000;
 
+	config.min_snr_kick_delay = 5 * 1000;
+
 	config.load_kick_enabled = false;
 	config.load_kick_threshold = 75;
 	config.load_kick_delay = 10 * 1000;

openwrt/usteer/files/etc/config/usteer

@@ -56,6 +56,9 @@ config usteer
 	# Minimum signal-to-noise ratio or signal level (dBm) to remain connected
 	#option min_snr 0
 
+	# Timeout after which a station with snr < min_snr will be kicked
+	#option min_snr_kick_delay 5000
+
 	# Timeout (in ms) after which a association following a disassociation is not seen
 	# as a roam
 	#option roam_process_timeout 5000

openwrt/usteer/files/etc/init.d/usteer

@@ -78,7 +78,7 @@ uci_usteer() {
 		max_neighbor_reports max_retry_band seen_policy_timeout \
 		load_balancing_threshold band_steering_threshold \
 		remote_update_interval remote_node_timeout\
-		min_connect_snr min_snr signal_diff_threshold \
+		min_connect_snr min_snr min_snr_kick_delay signal_diff_threshold \
 		initial_connect_delay roam_process_timeout\
 		roam_kick_delay roam_scan_tries roam_scan_timeout \
 		roam_scan_snr roam_scan_interval \

policy.c

@@ -422,6 +422,7 @@ usteer_local_node_roam_check(struct usteer_local_node *ln, struct uevent *ev)
 static void
 usteer_local_node_snr_kick(struct usteer_local_node *ln)
 {
+	unsigned int min_count = DIV_ROUND_UP(config.min_snr_kick_delay, config.local_sta_update);
 	struct uevent ev = {
 		.node_local = &ln->node,
 	};
@@ -438,7 +439,14 @@ usteer_local_node_snr_kick(struct usteer_local_node *ln)
 		if (si->connected != STA_CONNECTED)
 			continue;
 
-		if (si->signal >= min_signal)
+		if (si->signal >= min_signal) {
+			si->below_min_snr = 0;
+			continue;
+		} else {
+			si->below_min_snr++;
+		}
+
+		if (si->below_min_snr <= min_count)
 			continue;
 
 		si->kick_count++;

ubus.c

@@ -156,6 +156,7 @@ struct cfg_item {
 	_cfg(BOOL, assoc_steering), \
 	_cfg(I32, min_connect_snr), \
 	_cfg(I32, min_snr), \
+	_cfg(U32, min_snr_kick_delay), \
 	_cfg(U32, roam_process_timeout), \
 	_cfg(I32, roam_scan_snr), \
 	_cfg(U32, roam_scan_tries), \

usteer.h

@@ -165,6 +165,7 @@ struct usteer_config {
 	uint32_t remote_node_timeout;
 
 	int32_t min_snr;
+	uint32_t min_snr_kick_delay;
 	int32_t min_connect_snr;
 	uint32_t signal_diff_threshold;
 
@@ -242,6 +243,8 @@ struct sta_info {
 
 	int kick_count;
 
+	uint32_t below_min_snr;
+
 	uint8_t scan_band : 1;
 	uint8_t connected : 2;
 };