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>

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 026bf2f..f5dd235 100644 (file)
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -2886,6 +2886,20 @@ void initialize_tty_struct(struct tty_struct *tty,
        tty->dev = tty_get_device(tty);
 }
 
+/**
+ *     deinitialize_tty_struct
+ *     @tty: tty to deinitialize
+ *
+ *     This subroutine deinitializes a tty structure that has been newly
+ *     allocated but tty_release cannot be called on that yet.
+ *
+ *     Locking: none - tty in question must not be exposed at this point
+ */
+void deinitialize_tty_struct(struct tty_struct *tty)
+{
+       tty_ldisc_deinit(tty);
+}
+
 /**
  *     tty_put_char    -       write one character to a tty
  *     @tty: tty

diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index e19e136..5d01d32 100644 (file)
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -956,6 +956,19 @@ void tty_ldisc_init(struct tty_struct *tty)
        tty_ldisc_assign(tty, ld);
 }
 
+/**
+ *     tty_ldisc_init          -       ldisc cleanup for new tty
+ *     @tty: tty that was allocated recently
+ *
+ *     The tty structure must not becompletely set up (tty_ldisc_setup) when
+ *      this call is made.
+ */
+void tty_ldisc_deinit(struct tty_struct *tty)
+{
+       put_ldisc(tty->ldisc);
+       tty_ldisc_assign(tty, NULL);
+}
+
 void tty_ldisc_begin(void)
 {
        /* Setup the default TTY line discipline. */

diff --git a/include/linux/tty.h b/include/linux/tty.h
index 9f469c7..4db4ca7 100644 (file)
--- 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);