Current code doesn't update the symlinks in /sys/dev/char when we add/remove
tty lines. Fixing that allows to stop messing with ->valid before the driver
registration, which is a Good Thing(tm) - we shouldn't have it set before we
really have the things set up and ready for line_open().
We need tty_driver available to call tty_{un,}register_device(), so we just
stash a reference to it into struct line_driver.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>
cfe6b7c79d