tag	line	file	source code
TTY_BH	59	kernel/chr_drv/pty.c	mark_bh(TTY_BH);
TTY_BH	270	kernel/chr_drv/serial.c	mark_bh(TTY_BH);
TTY_BH	1526	kernel/chr_drv/tty_io.c	bh_base[TTY_BH].routine = tty_bh_routine;