tty: use for_each_console() and WARN() on sysfs failures

This fixes the build warnings in the tty code, and uses the proper
function for iterating over the console devices.
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/tty/tty_io.c

@@ -3257,7 +3257,7 @@ static ssize_t show_cons_active(struct device *dev,
 	ssize_t count = 0;
 
 	acquire_console_sem();
-	for (c = console_drivers; c; c = c->next) {
+	for_each_console(c) {
 		if (!c->device)
 			continue;
 		if (!c->write)
@@ -3306,7 +3306,7 @@ int __init tty_init(void)
 	if (IS_ERR(consdev))
 		consdev = NULL;
 	else
-		device_create_file(consdev, &dev_attr_active);
+		WARN_ON(device_create_file(consdev, &dev_attr_active) < 0);
 
 #ifdef CONFIG_VT
 	vty_init(&console_fops);

drivers/tty/vt/vt.c

@@ -2994,7 +2994,7 @@ int __init vty_init(const struct file_operations *console_fops)
 	if (IS_ERR(tty0dev))
 		tty0dev = NULL;
 	else
-		device_create_file(tty0dev, &dev_attr_active);
+		WARN_ON(device_create_file(tty0dev, &dev_attr_active) < 0);
 
 	vcs_init();