Commit bfb07599 authored by Alexey Dobriyan's avatar Alexey Dobriyan Committed by Linus Torvalds

[PATCH] Introduce tty_unregister_ldisc()

It's a bit strange to see tty_register_ldisc call in modules' exit
functions.
Signed-off-by: default avatarAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 790a19cd
......@@ -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.
......
......@@ -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;
......
......@@ -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);
......
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