Postpone global_init() call until first driver instance is initialized

This avoids allocating global driver state for driver wrappers that
are built in but not used. This can save some resources and avoids
failures with driver_nl80211.c that is now initializing netlink
connections for nl80211 in global_init().

hostapd/main.c

@@ -257,10 +257,22 @@ static int hostapd_driver_init(struct hostapd_iface *iface)
 
 	os_memset(&params, 0, sizeof(params));
 	for (i = 0; wpa_drivers[i]; i++) {
-		if (wpa_drivers[i] == hapd->driver) {
-			params.global_priv = global.drv_priv[i];
-			break;
+		if (wpa_drivers[i] != hapd->driver)
+			continue;
+
+		if (global.drv_priv[i] == NULL &&
+		    wpa_drivers[i]->global_init) {
+			global.drv_priv[i] = wpa_drivers[i]->global_init();
+			if (global.drv_priv[i] == NULL) {
+				wpa_printf(MSG_ERROR, "Failed to initialize "
+					   "driver '%s'",
+					   wpa_drivers[i]->name);
+				return -1;
+			}
 		}
+
+		params.global_priv = global.drv_priv[i];
+		break;
 	}
 	params.bssid = b;
 	params.ifname = hapd->conf->iface;
@@ -425,16 +437,6 @@ static int hostapd_global_init(struct hapd_interfaces *interfaces,
 	global.drv_priv = os_zalloc(global.drv_count * sizeof(void *));
 	if (global.drv_priv == NULL)
 		return -1;
-	for (i = 0; wpa_drivers[i]; i++) {
-		if (!wpa_drivers[i]->global_init)
-			continue;
-		global.drv_priv[i] = wpa_drivers[i]->global_init();
-		if (global.drv_priv[i] == NULL) {
-			wpa_printf(MSG_ERROR, "Failed to initialize driver "
-				   "'%s'", wpa_drivers[i]->name);
-			return -1;
-		}
-	}
 
 	return 0;
 }

wpa_supplicant/wpa_supplicant.c

@@ -1867,6 +1867,26 @@ struct wpa_ssid * wpa_supplicant_get_ssid(struct wpa_supplicant *wpa_s)
 }
 
 
+static int select_driver(struct wpa_supplicant *wpa_s, int i)
+{
+	struct wpa_global *global = wpa_s->global;
+
+	if (wpa_drivers[i]->global_init && global->drv_priv[i] == NULL) {
+		global->drv_priv[i] = wpa_drivers[i]->global_init();
+		if (global->drv_priv[i] == NULL) {
+			wpa_printf(MSG_ERROR, "Failed to initialize driver "
+				   "'%s'", wpa_drivers[i]->name);
+			return -1;
+		}
+	}
+
+	wpa_s->driver = wpa_drivers[i];
+	wpa_s->global_drv_priv = global->drv_priv[i];
+
+	return 0;
+}
+
+
 static int wpa_supplicant_set_driver(struct wpa_supplicant *wpa_s,
 				     const char *name)
 {
@@ -1885,9 +1905,7 @@ static int wpa_supplicant_set_driver(struct wpa_supplicant *wpa_s,
 
 	if (name == NULL) {
 		/* default to first driver in the list */
-		wpa_s->driver = wpa_drivers[0];
-		wpa_s->global_drv_priv = wpa_s->global->drv_priv[0];
-		return 0;
+		return select_driver(wpa_s, 0);
 	}
 
 	do {
@@ -1900,12 +1918,8 @@ static int wpa_supplicant_set_driver(struct wpa_supplicant *wpa_s,
 		for (i = 0; wpa_drivers[i]; i++) {
 			if (os_strlen(wpa_drivers[i]->name) == len &&
 			    os_strncmp(driver, wpa_drivers[i]->name, len) ==
-			    0) {
-				wpa_s->driver = wpa_drivers[i];
-				wpa_s->global_drv_priv =
-					wpa_s->global->drv_priv[i];
-				return 0;
-			}
+			    0)
+				return select_driver(wpa_s, i);
 		}
 
 		driver = pos + 1;
@@ -2625,17 +2639,6 @@ struct wpa_global * wpa_supplicant_init(struct wpa_params *params)
 		wpa_supplicant_deinit(global);
 		return NULL;
 	}
-	for (i = 0; wpa_drivers[i]; i++) {
-		if (!wpa_drivers[i]->global_init)
-			continue;
-		global->drv_priv[i] = wpa_drivers[i]->global_init();
-		if (global->drv_priv[i] == NULL) {
-			wpa_printf(MSG_ERROR, "Failed to initialize driver "
-				   "'%s'", wpa_drivers[i]->name);
-			wpa_supplicant_deinit(global);
-			return NULL;
-		}
-	}
 
 	return global;
 }