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-rw-r--r--Documentation/tty.txt2
-rw-r--r--drivers/char/tty_io.c37
-rw-r--r--include/linux/tty.h1
3 files changed, 26 insertions, 14 deletions
diff --git a/Documentation/tty.txt b/Documentation/tty.txt
index 3958cf746dde..8ff7bc2a0811 100644
--- a/Documentation/tty.txt
+++ b/Documentation/tty.txt
@@ -22,7 +22,7 @@ copy of the structure. You must not re-register over the top of the line
discipline even with the same data or your computer again will be eaten by
demons.
-In order to remove a line discipline call tty_register_ldisc passing NULL.
+In order to remove a line discipline call tty_unregister_ldisc().
In ancient times this always worked. In modern times the function will
return -EBUSY if the ldisc is currently in use. Since the ldisc referencing
code manages the module counts this should not usually be a concern.
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 31831030f73f..cc4b43bad703 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -251,7 +251,7 @@ static void tty_set_termios_ldisc(struct tty_struct *tty, int num)
static DEFINE_SPINLOCK(tty_ldisc_lock);
static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_wait);
-static struct tty_ldisc tty_ldiscs[NR_LDISCS]; /* line disc dispatch table */
+static struct tty_ldisc tty_ldiscs[NR_LDISCS]; /* line disc dispatch table */
int tty_register_ldisc(int disc, struct tty_ldisc *new_ldisc)
{
@@ -262,24 +262,35 @@ int tty_register_ldisc(int disc, struct tty_ldisc *new_ldisc)
return -EINVAL;
spin_lock_irqsave(&tty_ldisc_lock, flags);
- if (new_ldisc) {
- tty_ldiscs[disc] = *new_ldisc;
- tty_ldiscs[disc].num = disc;
- tty_ldiscs[disc].flags |= LDISC_FLAG_DEFINED;
- tty_ldiscs[disc].refcount = 0;
- } else {
- if(tty_ldiscs[disc].refcount)
- ret = -EBUSY;
- else
- tty_ldiscs[disc].flags &= ~LDISC_FLAG_DEFINED;
- }
+ tty_ldiscs[disc] = *new_ldisc;
+ tty_ldiscs[disc].num = disc;
+ tty_ldiscs[disc].flags |= LDISC_FLAG_DEFINED;
+ tty_ldiscs[disc].refcount = 0;
spin_unlock_irqrestore(&tty_ldisc_lock, flags);
return ret;
}
-
EXPORT_SYMBOL(tty_register_ldisc);
+int tty_unregister_ldisc(int disc)
+{
+ unsigned long flags;
+ int ret = 0;
+
+ if (disc < N_TTY || disc >= NR_LDISCS)
+ return -EINVAL;
+
+ spin_lock_irqsave(&tty_ldisc_lock, flags);
+ if (tty_ldiscs[disc].refcount)
+ ret = -EBUSY;
+ else
+ tty_ldiscs[disc].flags &= ~LDISC_FLAG_DEFINED;
+ spin_unlock_irqrestore(&tty_ldisc_lock, flags);
+
+ return ret;
+}
+EXPORT_SYMBOL(tty_unregister_ldisc);
+
struct tty_ldisc *tty_ldisc_get(int disc)
{
unsigned long flags;
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 1b76106272d3..59ff42c629ec 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -345,6 +345,7 @@ extern int tty_check_change(struct tty_struct * tty);
extern void stop_tty(struct tty_struct * tty);
extern void start_tty(struct tty_struct * tty);
extern int tty_register_ldisc(int disc, struct tty_ldisc *new_ldisc);
+extern int tty_unregister_ldisc(int disc);
extern int tty_register_driver(struct tty_driver *driver);
extern int tty_unregister_driver(struct tty_driver *driver);
extern void tty_register_device(struct tty_driver *driver, unsigned index, struct device *dev);