WPS ER: Stop eloop only on the last terminate_cb

This allows all WPS ER instances to be cleaned up properly if more
than one interface has an active WPS ER when wpa_supplicant is being
killed.

wpa_supplicant/wps_supplicant.c

@@ -1543,10 +1543,13 @@ int wpas_wps_er_config(struct wpa_supplicant *wpa_s, const char *uuid,
 }
 
 
+static int callbacks_pending = 0;
+
 static void wpas_wps_terminate_cb(void *ctx)
 {
 	wpa_printf(MSG_DEBUG, "WPS ER: Terminated");
-	eloop_terminate();
+	if (--callbacks_pending <= 0)
+		eloop_terminate();
 }
 #endif /* CONFIG_WPS_ER */
 
@@ -1555,6 +1558,7 @@ int wpas_wps_terminate_pending(struct wpa_supplicant *wpa_s)
 {
 #ifdef CONFIG_WPS_ER
 	if (wpa_s->wps_er) {
+		callbacks_pending++;
 		wps_er_deinit(wpa_s->wps_er, wpas_wps_terminate_cb, wpa_s);
 		wpa_s->wps_er = NULL;
 		return 1;