bgscan learn: Skip immediate scan on initial signal event

The driver is likely to indicate an immediate signal event when the
threshold value is configured. Since we do this immediately after
association, there is not much point in requesting a new scan to be
started based on this event.

wpa_supplicant/bgscan_learn.c

@@ -428,6 +428,15 @@ static void * bgscan_learn_init(struct wpa_supplicant *wpa_s,
 	data->scan_interval = data->short_interval;
 	eloop_register_timeout(data->scan_interval, 0, bgscan_learn_timeout,
 			       data, NULL);
+
+	/*
+	 * This function is called immediately after an association, so it is
+	 * reasonable to assume that a scan was completed recently. This makes
+	 * us skip an immediate new scan in cases where the current signal
+	 * level is below the bgscan threshold.
+	 */
+	os_get_time(&data->last_bgscan);
+
 	return data;
 }
 
@@ -550,6 +559,7 @@ static void bgscan_learn_notify_signal_change(void *priv, int above,
 					      int current_signal)
 {
 	struct bgscan_learn_data *data = priv;
+	struct os_time now;
 
 	if (data->short_interval == data->long_interval ||
 	    data->signal_threshold == 0)
@@ -558,12 +568,12 @@ static void bgscan_learn_notify_signal_change(void *priv, int above,
 	wpa_printf(MSG_DEBUG, "bgscan learn: signal level changed "
 		   "(above=%d current_signal=%d)", above, current_signal);
 	if (data->scan_interval == data->long_interval && !above) {
-		wpa_printf(MSG_DEBUG, "bgscan learn: Trigger immediate scan "
-			   "and start using short bgscan interval");
+		wpa_printf(MSG_DEBUG, "bgscan learn: Start using short bgscan "
+			   "interval");
 		data->scan_interval = data->short_interval;
-		eloop_cancel_timeout(bgscan_learn_timeout, data, NULL);
-		eloop_register_timeout(0, 0, bgscan_learn_timeout, data,
-				       NULL);
+		os_get_time(&now);
+		if (now.sec > data->last_bgscan.sec + 1)
+			scan = 1;
 	} else if (data->scan_interval == data->short_interval && above) {
 		wpa_printf(MSG_DEBUG, "bgscan learn: Start using long bgscan "
 			   "interval");
@@ -572,20 +582,19 @@ static void bgscan_learn_notify_signal_change(void *priv, int above,
 		eloop_register_timeout(data->scan_interval, 0,
 				       bgscan_learn_timeout, data, NULL);
 	} else if (!above) {
-		struct os_time now;
 		/*
 		 * Signal dropped further 4 dB. Request a new scan if we have
 		 * not yet scanned in a while.
 		 */
 		os_get_time(&now);
-		if (now.sec > data->last_bgscan.sec + 10) {
-			wpa_printf(MSG_DEBUG, "bgscan learn: Trigger "
-				   "immediate scan");
-			eloop_cancel_timeout(bgscan_learn_timeout, data,
-					     NULL);
-			eloop_register_timeout(0, 0, bgscan_learn_timeout,
-					       data, NULL);
-		}
+		if (now.sec > data->last_bgscan.sec + 10)
+			scan = 1;
+	}
+
+	if (scan) {
+		wpa_printf(MSG_DEBUG, "bgscan learn: Trigger immediate scan");
+		eloop_cancel_timeout(bgscan_learn_timeout, data, NULL);
+		eloop_register_timeout(0, 0, bgscan_learn_timeout, data, NULL);
 	}
 }