tty: Fix lock order in tty_do_resize()

[linux-2.6-block.git] / drivers / tty / tty_io.c

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 2174698dd6f722035235916fbd9ed7030c807d4c..26bb78c30a00948fb08de571c8001ab9bf86ef36 100644 (file)
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -2229,7 +2229,7 @@ static int tiocsti(struct tty_struct *tty, char __user *p)
  *
  *     Copies the kernel idea of the window size into the user buffer.
  *
- *     Locking: tty->termios_rwsem is taken to ensure the winsize data
+ *     Locking: tty->winsize_mutex is taken to ensure the winsize data
  *             is consistent.
  */
 
@@ -2237,9 +2237,9 @@ static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
 {
        int err;
 
-       down_read(&tty->termios_rwsem);
+       mutex_lock(&tty->winsize_mutex);
        err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
-       up_read(&tty->termios_rwsem);
+       mutex_unlock(&tty->winsize_mutex);
 
        return err ? -EFAULT: 0;
 }
@@ -2260,7 +2260,7 @@ int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
        unsigned long flags;
 
        /* Lock the tty */
-       down_write(&tty->termios_rwsem);
+       mutex_lock(&tty->winsize_mutex);
        if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
                goto done;
        /* Get the PID values and reference them so we can
@@ -2275,7 +2275,7 @@ int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
 
        tty->winsize = *ws;
 done:
-       up_write(&tty->termios_rwsem);
+       mutex_unlock(&tty->winsize_mutex);
        return 0;
 }
 EXPORT_SYMBOL(tty_do_resize);
@@ -3016,6 +3016,7 @@ void initialize_tty_struct(struct tty_struct *tty,
        mutex_init(&tty->legacy_mutex);
        mutex_init(&tty->throttle_mutex);
        init_rwsem(&tty->termios_rwsem);
+       mutex_init(&tty->winsize_mutex);
        init_ldsem(&tty->ldisc_sem);
        init_waitqueue_head(&tty->write_wait);
        init_waitqueue_head(&tty->read_wait);