tty: Replace ASYNC_INITIALIZED bit and update atomically

Replace ASYNC_INITIALIZED bit in the tty_port::flags field with
TTY_PORT_INITIALIZED bit in the tty_port::iflags field. Introduce helpers
tty_port_set_initialized() and tty_port_initialized() to abstract
atomic bit ops.

Note: the transforms for test_and_set_bit() and test_and_clear_bit()
are unnecessary as the state transitions are already mutually exclusive;
the tty lock prevents concurrent open/close/hangup.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 7ac5add..bf1bcdb 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -610,6 +610,19 @@
 		clear_bit(TTY_PORT_SUSPENDED, &port->iflags);
 }
 
+static inline bool tty_port_initialized(struct tty_port *port)
+{
+	return test_bit(TTY_PORT_INITIALIZED, &port->iflags);
+}
+
+static inline void tty_port_set_initialized(struct tty_port *port, bool val)
+{
+	if (val)
+		set_bit(TTY_PORT_INITIALIZED, &port->iflags);
+	else
+		clear_bit(TTY_PORT_INITIALIZED, &port->iflags);
+}
+
 extern struct tty_struct *tty_port_tty_get(struct tty_port *port);
 extern void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty);
 extern int tty_port_carrier_raised(struct tty_port *port);