nl80211: Fix monitor interface reference counting

The first user of monitor interface was not counted and that could
result in the monitor interface getting removed if the initial interface
was removed from a multi-BSS setup.

Signed-hostap: Jouni Malinen <jouni@qca.qualcomm.com>

src/drivers/driver_nl80211.c

@@ -7378,7 +7378,10 @@ static int add_monitor_filter(int s)
 static void nl80211_remove_monitor_interface(
 	struct wpa_driver_nl80211_data *drv)
 {
-	drv->monitor_refcount--;
+	if (drv->monitor_refcount > 0)
+		drv->monitor_refcount--;
+	wpa_printf(MSG_DEBUG, "nl80211: Remove monitor interface: refcount=%d",
+		   drv->monitor_refcount);
 	if (drv->monitor_refcount > 0)
 		return;
 
@@ -7404,6 +7407,8 @@ nl80211_create_monitor_interface(struct wpa_driver_nl80211_data *drv)
 
 	if (drv->monitor_ifidx >= 0) {
 		drv->monitor_refcount++;
+		wpa_printf(MSG_DEBUG, "nl80211: Re-use existing monitor interface: refcount=%d",
+			   drv->monitor_refcount);
 		return 0;
 	}
 
@@ -7481,6 +7486,7 @@ nl80211_create_monitor_interface(struct wpa_driver_nl80211_data *drv)
 		goto error;
 	}
 
+	drv->monitor_refcount++;
 	return 0;
  error:
 	nl80211_remove_monitor_interface(drv);
@@ -7492,8 +7498,8 @@ static int nl80211_setup_ap(struct i802_bss *bss)
 {
 	struct wpa_driver_nl80211_data *drv = bss->drv;
 
-	wpa_printf(MSG_DEBUG, "nl80211: Setup AP - device_ap_sme=%d "
-		   "use_monitor=%d", drv->device_ap_sme, drv->use_monitor);
+	wpa_printf(MSG_DEBUG, "nl80211: Setup AP(%s) - device_ap_sme=%d use_monitor=%d",
+		   bss->ifname, drv->device_ap_sme, drv->use_monitor);
 
 	/*
 	 * Disable Probe Request reporting unless we need it in this way for
@@ -7531,6 +7537,8 @@ static void nl80211_teardown_ap(struct i802_bss *bss)
 {
 	struct wpa_driver_nl80211_data *drv = bss->drv;
 
+	wpa_printf(MSG_DEBUG, "nl80211: Teardown AP(%s) - device_ap_sme=%d use_monitor=%d",
+		   bss->ifname, drv->device_ap_sme, drv->use_monitor);
 	if (drv->device_ap_sme) {
 		wpa_driver_nl80211_probe_req_report(bss, 0);
 		if (!drv->use_monitor)