diff options
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/pty.c | 25 | ||||
| -rw-r--r-- | drivers/tty/tty_io.c | 20 | ||||
| -rw-r--r-- | drivers/tty/tty_ldisc.c | 3 |
3 files changed, 37 insertions, 11 deletions
diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c index 60c08ce8378..d6579a9064c 100644 --- a/drivers/tty/pty.c +++ b/drivers/tty/pty.c @@ -282,6 +282,17 @@ done: return 0; } +/** + * pty_common_install - set up the pty pair + * @driver: the pty driver + * @tty: the tty being instantiated + * @bool: legacy, true if this is BSD style + * + * Perform the initial set up for the tty/pty pair. Called from the + * tty layer when the port is first opened. + * + * Locking: the caller must hold the tty_mutex + */ static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty, bool legacy) { @@ -364,6 +375,14 @@ static int pty_install(struct tty_driver *driver, struct tty_struct *tty) return pty_common_install(driver, tty, true); } +static void pty_remove(struct tty_driver *driver, struct tty_struct *tty) +{ + struct tty_struct *pair = tty->link; + driver->ttys[tty->index] = NULL; + if (pair) + pair->driver->ttys[pair->index] = NULL; +} + static int pty_bsd_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg) { @@ -395,7 +414,8 @@ static const struct tty_operations master_pty_ops_bsd = { .set_termios = pty_set_termios, .ioctl = pty_bsd_ioctl, .cleanup = pty_cleanup, - .resize = pty_resize + .resize = pty_resize, + .remove = pty_remove }; static const struct tty_operations slave_pty_ops_bsd = { @@ -409,7 +429,8 @@ static const struct tty_operations slave_pty_ops_bsd = { .unthrottle = pty_unthrottle, .set_termios = pty_set_termios, .cleanup = pty_cleanup, - .resize = pty_resize + .resize = pty_resize, + .remove = pty_remove }; static void __init legacy_pty_init(void) diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index be18d60ddf4..c6f4d711771 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -1465,7 +1465,6 @@ EXPORT_SYMBOL(tty_free_termios); * in use. It also gets called when setup of a device fails. * * Locking: - * tty_mutex - sometimes only * takes the file list lock internally when working on the list * of ttys that the driver keeps. * @@ -1526,17 +1525,16 @@ EXPORT_SYMBOL(tty_kref_put); * and decrement the refcount of the backing module. * * Locking: - * tty_mutex - sometimes only + * tty_mutex * takes the file list lock internally when working on the list * of ttys that the driver keeps. - * FIXME: should we require tty_mutex is held here ?? * */ static void release_tty(struct tty_struct *tty, int idx) { /* This should always be true but check for the moment */ WARN_ON(tty->index != idx); - + WARN_ON(!mutex_is_locked(&tty_mutex)); if (tty->ops->shutdown) tty->ops->shutdown(tty); tty_free_termios(tty); @@ -1708,6 +1706,9 @@ int tty_release(struct inode *inode, struct file *filp) * The closing flags are now consistent with the open counts on * both sides, and we've completed the last operation that could * block, so it's safe to proceed with closing. + * + * We must *not* drop the tty_mutex until we ensure that a further + * entry into tty_open can not pick up this tty. */ if (pty_master) { if (--o_tty->count < 0) { @@ -1759,12 +1760,13 @@ int tty_release(struct inode *inode, struct file *filp) } mutex_unlock(&tty_mutex); + tty_unlock(); + /* At this point the TTY_CLOSING flag should ensure a dead tty + cannot be re-opened by a racing opener */ /* check whether both sides are closing ... */ - if (!tty_closing || (o_tty && !o_tty_closing)) { - tty_unlock(); + if (!tty_closing || (o_tty && !o_tty_closing)) return 0; - } #ifdef TTY_DEBUG_HANGUP printk(KERN_DEBUG "%s: freeing tty structure...\n", __func__); @@ -1777,12 +1779,14 @@ int tty_release(struct inode *inode, struct file *filp) * The release_tty function takes care of the details of clearing * the slots and preserving the termios structure. */ + mutex_lock(&tty_mutex); release_tty(tty, idx); + mutex_unlock(&tty_mutex); /* Make this pty number available for reallocation */ if (devpts) devpts_kill_index(inode, idx); - tty_unlock(); + return 0; } diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c index e6156c60d19..3d0687197d0 100644 --- a/drivers/tty/tty_ldisc.c +++ b/drivers/tty/tty_ldisc.c @@ -912,7 +912,6 @@ void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty) * race with the set_ldisc code path. */ - tty_unlock(); tty_ldisc_halt(tty); tty_ldisc_flush_works(tty); tty_lock(); @@ -930,6 +929,8 @@ void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty) tty_set_termios_ldisc(tty, N_TTY); mutex_unlock(&tty->ldisc_mutex); + tty_unlock(); + /* This will need doing differently if we need to lock */ if (o_tty) tty_ldisc_release(o_tty, NULL); |