[PATCH] Decrease cross-threshold roam difficulty

[Matthew Wang]

Decrease the roam difficulty when roaming across the short background
scan threshold (i.e. when the current BSS RSSI is below the threshold
and the selected BSS RSSI is above the threshold). This tends to happen
in normal roaming scenarios when moving from the domain of one AP to
the domain of another.

Signed-off-by: Matthew Wang <matthewmwang at chromium.org>
---
 wpa_supplicant/bgscan_simple.c    | 5 ++++-
 wpa_supplicant/events.c           | 3 +++
 wpa_supplicant/wpa_supplicant_i.h | 1 +
 3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/wpa_supplicant/bgscan_simple.c b/wpa_supplicant/bgscan_simple.c
index cac3049e3..a90cf86e5 100644
--- a/wpa_supplicant/bgscan_simple.c
+++ b/wpa_supplicant/bgscan_simple.c
@@ -189,6 +189,7 @@ static void * bgscan_simple_init(struct wpa_supplicant *wpa_s,
 	data->scan_interval = data->short_interval;
 	data->max_short_scans = data->long_interval / data->short_interval + 1;
 	if (data->signal_threshold) {
+		wpa_s->signal_threshold = data->signal_threshold;
 		/* Poll for signal info to set initial scan interval */
 		struct wpa_signal_info siginfo;
 		if (wpa_drv_signal_poll(wpa_s, &siginfo) == 0 &&
@@ -216,8 +217,10 @@ static void bgscan_simple_deinit(void *priv)
 {
 	struct bgscan_simple_data *data = priv;
 	eloop_cancel_timeout(bgscan_simple_timeout, data, NULL);
-	if (data->signal_threshold)
+	if (data->signal_threshold) {
+		data->wpa_s->signal_threshold = 0;
 		wpa_drv_signal_monitor(data->wpa_s, 0, 0);
+	}
 	os_free(data);
 }
 
diff --git a/wpa_supplicant/events.c b/wpa_supplicant/events.c
index 7bea64986..47169c181 100644
--- a/wpa_supplicant/events.c
+++ b/wpa_supplicant/events.c
@@ -2284,6 +2284,9 @@ int wpa_supplicant_need_to_roam_within_ess(struct wpa_supplicant *wpa_s,
 		min_diff -= 2;
 	if (to_6ghz)
 		min_diff -= 2;
+	if (wpa_s->signal_threshold && cur_level <= wpa_s->signal_threshold &&
+	    sel_level > wpa_s->signal_threshold)
+		min_diff -= 2;
 	diff = sel_level - cur_level;
 	if (diff < min_diff) {
 		wpa_dbg(wpa_s, MSG_DEBUG,
diff --git a/wpa_supplicant/wpa_supplicant_i.h b/wpa_supplicant/wpa_supplicant_i.h
index b3f1cd1b4..86c25bd8d 100644
--- a/wpa_supplicant/wpa_supplicant_i.h
+++ b/wpa_supplicant/wpa_supplicant_i.h
@@ -1191,6 +1191,7 @@ struct wpa_supplicant {
 	struct wpa_ssid *bgscan_ssid;
 	const struct bgscan_ops *bgscan;
 	void *bgscan_priv;
+	int signal_threshold;
 
 	const struct autoscan_ops *autoscan;
 	struct wpa_driver_scan_params *autoscan_params;
-- 
2.43.0.472.g3155946c3a-goog