static int con_put_char(struct tty_struct *tty, unsigned char ch)
{
	if (in_interrupt())
		return 0;	/* n_r3964 calls put_char() from interrupt context */
	return do_con_write(tty, &ch, 1);
}
static int con_put_char(struct tty_struct *tty, unsigned char ch)
{
	if (in_interrupt())
		return 0;	 
	return do_con_write(tty, &ch, 1);
}