diff options
Diffstat (limited to 'drivers/tty/tty_mutex.c')
| -rw-r--r-- | drivers/tty/tty_mutex.c | 32 |
1 files changed, 13 insertions, 19 deletions
diff --git a/drivers/tty/tty_mutex.c b/drivers/tty/tty_mutex.c index 2e41abebbcba..f43e995c7a0f 100644 --- a/drivers/tty/tty_mutex.c +++ b/drivers/tty/tty_mutex.c @@ -4,6 +4,11 @@ #include <linux/semaphore.h> #include <linux/sched.h> +/* + * Nested tty locks are necessary for releasing pty pairs. + * The stable lock order is master pty first, then slave pty. + */ + /* Legacy tty mutex glue */ enum { @@ -45,29 +50,18 @@ void __lockfunc tty_unlock(struct tty_struct *tty) } EXPORT_SYMBOL(tty_unlock); -/* - * Getting the big tty mutex for a pair of ttys with lock ordering - * On a non pty/tty pair tty2 can be NULL which is just fine. - */ -void __lockfunc tty_lock_pair(struct tty_struct *tty, - struct tty_struct *tty2) +void __lockfunc tty_lock_slave(struct tty_struct *tty) { - if (tty < tty2) { - tty_lock(tty); - tty_lock_nested(tty2, TTY_MUTEX_NESTED); - } else { - if (tty2 && tty2 != tty) - tty_lock(tty2); + if (tty && tty != tty->link) { + WARN_ON(!mutex_is_locked(&tty->link->legacy_mutex) || + !tty->driver->type == TTY_DRIVER_TYPE_PTY || + !tty->driver->type == PTY_TYPE_SLAVE); tty_lock_nested(tty, TTY_MUTEX_NESTED); } } -EXPORT_SYMBOL(tty_lock_pair); -void __lockfunc tty_unlock_pair(struct tty_struct *tty, - struct tty_struct *tty2) +void __lockfunc tty_unlock_slave(struct tty_struct *tty) { - tty_unlock(tty); - if (tty2 && tty2 != tty) - tty_unlock(tty2); + if (tty && tty != tty->link) + tty_unlock(tty); } -EXPORT_SYMBOL(tty_unlock_pair); |