diff options
Diffstat (limited to 'drivers/tty/tty_ldisc.c')
| -rw-r--r-- | drivers/tty/tty_ldisc.c | 49 |
1 files changed, 42 insertions, 7 deletions
diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c index 412f9775d19c..d8e96b005023 100644 --- a/drivers/tty/tty_ldisc.c +++ b/drivers/tty/tty_ldisc.c @@ -47,6 +47,7 @@ static DEFINE_SPINLOCK(tty_ldisc_lock); static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_wait); +static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_idle); /* Line disc dispatch table */ static struct tty_ldisc_ops *tty_ldiscs[NR_LDISCS]; @@ -83,6 +84,7 @@ static void put_ldisc(struct tty_ldisc *ld) return; } local_irq_restore(flags); + wake_up(&tty_ldisc_idle); } /** @@ -531,6 +533,23 @@ static int tty_ldisc_halt(struct tty_struct *tty) } /** + * tty_ldisc_wait_idle - wait for the ldisc to become idle + * @tty: tty to wait for + * + * Wait for the line discipline to become idle. The discipline must + * have been halted for this to guarantee it remains idle. + */ +static int tty_ldisc_wait_idle(struct tty_struct *tty) +{ + int ret; + ret = wait_event_interruptible_timeout(tty_ldisc_idle, + atomic_read(&tty->ldisc->users) == 1, 5 * HZ); + if (ret < 0) + return ret; + return ret > 0 ? 0 : -EBUSY; +} + +/** * tty_set_ldisc - set line discipline * @tty: the terminal to set * @ldisc: the line discipline @@ -634,8 +653,17 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc) flush_scheduled_work(); + retval = tty_ldisc_wait_idle(tty); + tty_lock(); mutex_lock(&tty->ldisc_mutex); + + /* handle wait idle failure locked */ + if (retval) { + tty_ldisc_put(new_ldisc); + goto enable; + } + if (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 */ @@ -669,6 +697,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc) tty_ldisc_put(o_ldisc); +enable: /* * Allow ldisc referencing to occur again */ @@ -714,9 +743,12 @@ static void tty_reset_termios(struct tty_struct *tty) * state closed */ -static void tty_ldisc_reinit(struct tty_struct *tty, int ldisc) +static int tty_ldisc_reinit(struct tty_struct *tty, int ldisc) { - struct tty_ldisc *ld; + struct tty_ldisc *ld = tty_ldisc_get(ldisc); + + if (IS_ERR(ld)) + return -1; tty_ldisc_close(tty, tty->ldisc); tty_ldisc_put(tty->ldisc); @@ -724,10 +756,10 @@ static void tty_ldisc_reinit(struct tty_struct *tty, int ldisc) /* * Switch the line discipline back */ - ld = tty_ldisc_get(ldisc); - BUG_ON(IS_ERR(ld)); tty_ldisc_assign(tty, ld); tty_set_termios_ldisc(tty, ldisc); + + return 0; } /** @@ -802,13 +834,16 @@ void tty_ldisc_hangup(struct tty_struct *tty) a FIXME */ if (tty->ldisc) { /* Not yet closed */ if (reset == 0) { - tty_ldisc_reinit(tty, tty->termios->c_line); - err = tty_ldisc_open(tty, tty->ldisc); + + if (!tty_ldisc_reinit(tty, tty->termios->c_line)) + err = tty_ldisc_open(tty, tty->ldisc); + else + err = 1; } /* If the re-open fails or we reset then go to N_TTY. The N_TTY open cannot fail */ if (reset || err) { - tty_ldisc_reinit(tty, N_TTY); + BUG_ON(tty_ldisc_reinit(tty, N_TTY)); WARN_ON(tty_ldisc_open(tty, tty->ldisc)); } tty_ldisc_enable(tty); |