bgscan simple: 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_simple.c

@@ -124,6 +124,15 @@ static void * bgscan_simple_init(struct wpa_supplicant *wpa_s,
 	data->scan_interval = data->short_interval;
 	eloop_register_timeout(data->scan_interval, 0, bgscan_simple_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;
 }
 
@@ -171,6 +180,8 @@ static void bgscan_simple_notify_signal_change(void *priv, int above,
 					       int current_signal)
 {
 	struct bgscan_simple_data *data = priv;
+	int scan = 0;
+	struct os_time now;
 
 	if (data->short_interval == data->long_interval ||
 	    data->signal_threshold == 0)
@@ -179,12 +190,12 @@ static void bgscan_simple_notify_signal_change(void *priv, int above,
 	wpa_printf(MSG_DEBUG, "bgscan simple: signal level changed "
 		   "(above=%d current_signal=%d)", above, current_signal);
 	if (data->scan_interval == data->long_interval && !above) {
-		wpa_printf(MSG_DEBUG, "bgscan simple: Trigger immediate scan "
-			   "and start using short bgscan interval");
+		wpa_printf(MSG_DEBUG, "bgscan simple: Start using short "
+			   "bgscan interval");
 		data->scan_interval = data->short_interval;
-		eloop_cancel_timeout(bgscan_simple_timeout, data, NULL);
-		eloop_register_timeout(0, 0, bgscan_simple_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 simple: Start using long bgscan "
 			   "interval");
@@ -193,20 +204,20 @@ static void bgscan_simple_notify_signal_change(void *priv, int above,
 		eloop_register_timeout(data->scan_interval, 0,
 				       bgscan_simple_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 simple: Trigger "
-				   "immediate scan");
-			eloop_cancel_timeout(bgscan_simple_timeout, data,
-					     NULL);
-			eloop_register_timeout(0, 0, bgscan_simple_timeout,
-					       data, NULL);
-		}
+		if (now.sec > data->last_bgscan.sec + 10)
+			scan = 1;
+	}
+
+	if (scan) {
+		wpa_printf(MSG_DEBUG, "bgscan simple: Trigger immediate scan");
+		eloop_cancel_timeout(bgscan_simple_timeout, data, NULL);
+		eloop_register_timeout(0, 0, bgscan_simple_timeout, data,
+				       NULL);
 	}
 }