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

[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

Documentation/tty.txt

+1 −1
Original line number Diff line number Diff line
@@ -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.

drivers/char/tty_io.c

+24 −13
Original line number Diff line number Diff line
@@ -262,23 +262,34 @@ 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 {

	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_register_ldisc);

EXPORT_SYMBOL(tty_unregister_ldisc);



struct tty_ldisc *tty_ldisc_get(int disc)

{

include/linux/tty.h

+1 −0
Original line number Diff line number Diff line
@@ -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);