Extern or forward variable declaration at include/linux/tty.h, line 570 References: drivers/tty/pty.c, line 844 drivers/tty/pty.c, line 848 drivers/tty/tty_io.c, line 142 drivers/tty/tty_io.c, line 363 drivers/tty/tty_io.c, line 377 drivers/tty/tty_io.c, line 409 drivers/tty/tty_io.c, line 427 drivers/tty/tty_io.c, line 1508 drivers/tty/tty_io.c, line 1592 drivers/tty/tty_io.c, line 1595 drivers/tty/tty_io.c, line 1624 drivers/tty/tty_io.c, line 1626 drivers/tty/tty_io.c, line 1895 drivers/tty/tty_io.c, line 1898 drivers/tty/tty_io.c, line 1918 drivers/tty/tty_io.c, line 1948 drivers/tty/tty_io.c, line 1951 drivers/tty/tty_io.c, line 1958 drivers/tty/tty_io.c, line 1965 drivers/tty/tty_io.c, line 1969 drivers/tty/tty_io.c, line 1985 drivers/tty/tty_io.c, line 3337 drivers/tty/tty_io.c, line 3339 drivers/tty/tty_io.c, line 3358 drivers/tty/tty_io.c, line 3360 drivers/tty/tty_io.c, line 3381 drivers/tty/tty_io.c, line 3383 fs/proc/proc_tty.c, line 108 fs/proc/proc_tty.c, line 119 include/linux/tty.h, line 570