* they are not on hot paths so a little discipline won't do
* any harm.
*
- * Locking: takes termios_mutex
+ * Locking: takes termios_rwsem
*/
static void tty_set_termios_ldisc(struct tty_struct *tty, int num)
{
- mutex_lock(&tty->termios_mutex);
+ down_write(&tty->termios_rwsem);
tty->termios.c_line = num;
- mutex_unlock(&tty->termios_mutex);
+ up_write(&tty->termios_rwsem);
}
/**
int tty_set_ldisc(struct tty_struct *tty, int ldisc)
{
int retval;
- struct tty_ldisc *o_ldisc, *new_ldisc;
+ struct tty_ldisc *old_ldisc, *new_ldisc;
struct tty_struct *o_tty = tty->link;
new_ldisc = tty_ldisc_get(tty, ldisc);
return 0;
}
- /* FIXME: why 'shutoff' input if the ldisc is locked? */
- tty->receive_room = 0;
-
- o_ldisc = tty->ldisc;
+ old_ldisc = tty->ldisc;
tty_lock(tty);
- /* FIXME: for testing only */
- WARN_ON(test_bit(TTY_HUPPED, &tty->flags));
-
- if (test_bit(TTY_HUPPING, &tty->flags)) {
+ if (test_bit(TTY_HUPPING, &tty->flags) ||
+ test_bit(TTY_HUPPED, &tty->flags)) {
/* We were raced by the hangup method. It will have stomped
the ldisc data and closed the ldisc down */
tty_ldisc_enable_pair(tty, o_tty);
return -EIO;
}
- /* Shutdown the current discipline. */
- tty_ldisc_close(tty, o_ldisc);
+ /* Shutdown the old discipline. */
+ tty_ldisc_close(tty, old_ldisc);
/* Now set up the new line discipline. */
tty->ldisc = new_ldisc;
if (retval < 0) {
/* Back to the old one or N_TTY if we can't */
tty_ldisc_put(new_ldisc);
- tty_ldisc_restore(tty, o_ldisc);
+ tty_ldisc_restore(tty, old_ldisc);
}
- /* At this point we hold a reference to the new ldisc and a
- a reference to the old ldisc. If we ended up flipping back
- to the existing ldisc we have two references to it */
-
- if (tty->ldisc->ops->num != o_ldisc->ops->num && tty->ops->set_ldisc)
+ if (tty->ldisc->ops->num != old_ldisc->ops->num && tty->ops->set_ldisc)
tty->ops->set_ldisc(tty);
- tty_ldisc_put(o_ldisc);
+ /* At this point we hold a reference to the new ldisc and a
+ reference to the old ldisc, or we hold two references to
+ the old ldisc (if it was restored as part of error cleanup
+ above). In either case, releasing a single reference from
+ the old ldisc is correct. */
+
+ tty_ldisc_put(old_ldisc);
/*
* Allow ldisc referencing to occur again
static void tty_reset_termios(struct tty_struct *tty)
{
- mutex_lock(&tty->termios_mutex);
+ down_write(&tty->termios_rwsem);
tty->termios = tty->driver->init_termios;
tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
- mutex_unlock(&tty->termios_mutex);
+ up_write(&tty->termios_rwsem);
}