TTY: introduce deinit helpers for proper ldisc shutdown

Introduce deinitialize_tty_struct which should be called after
initialize_tty_struct and before successfull tty_ldisc_setup.

It calls tty_ldisc_deinit which is opposite of tty_ldisc_init. It only
puts a reference to ldisc and assigns NULL to tty->ldisc.

It will be used to shut down ldisc when tty_release cannot be called
yet.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/tty.h b/include/linux/tty.h
index 9f469c700550..4db4ca79f895 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -472,6 +472,7 @@ extern int tty_add_file(struct tty_struct *tty, struct file *file);
 extern void free_tty_struct(struct tty_struct *tty);
 extern void initialize_tty_struct(struct tty_struct *tty,
                 struct tty_driver *driver, int idx);
+extern void deinitialize_tty_struct(struct tty_struct *tty);
 extern struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
                                                                 int first_ok);
 extern int tty_release(struct inode *inode, struct file *filp);
@@ -525,6 +526,7 @@ extern int tty_set_ldisc(struct tty_struct *tty, int ldisc);
 extern int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty);
 extern void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty);
 extern void tty_ldisc_init(struct tty_struct *tty);
+extern void tty_ldisc_deinit(struct tty_struct *tty);
 extern void tty_ldisc_begin(void);
 /* This last one is just for the tty layer internals and shouldn't be used elsewhere */
 extern void tty_ldisc_enable(struct tty_struct *tty);