[BUG]: 2.6.19.2: Weird serial core issue

["Aubrey Li" <aubreylee@gmail.com>]

I insert one printk into drivers/serial/serial_core.c:
uart_set_termios() to describe the issue.
static void uart_set_termios(struct tty_struct *tty, struct termios
*old_termios)
{
 ----snip----
        unsigned int cflag = tty->termios->c_cflag;

        BUG_ON(!kernel_locked());
+++printk("new_termios flag: 0x%x, old_termios flag: 0x%x\n");
+++             cflag, old_termios->c_cflag);

----snip ----
}

When I telnet my board and run the following command:
---- root:~> stty -F /dev/ttyS0 -crtscts

I got the following result from the console of my board:
---- root:~>new_termios flag: 0x1cb1, old_termios flag: 0x80001cb1

That's correct. CRTSCTS flag is clear

But when I type "ENTER" key on the console, I got:
----root:~>new_termios flag: 0x80001cb1, old_termios flag: 0x1cb1

The CRTSCTS flag is set back. But I didn't set it back, I just type "ENTER".
I guess, Is it a serial core bug?

-Aubrey