UPF_BUG_THRE     1736 drivers/tty/serial/8250/8250_pci.c 	port->port.flags |= UPF_BUG_THRE;
UPF_BUG_THRE     2233 drivers/tty/serial/8250/8250_port.c 		    up->port.flags & UPF_BUG_THRE) {