tty: Fix tty_send_xchar() lock order inversion

[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 0c41dbcb90b8bc7d8ab430d562206e7c2469411f..bcc8e1e8bb720996cf73438c67a397362173edca 100644 (file)
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1282,18 +1282,22 @@ int tty_send_xchar(struct tty_struct *tty, char ch)
        int     was_stopped = tty->stopped;
 
        if (tty->ops->send_xchar) {
+               down_read(&tty->termios_rwsem);
                tty->ops->send_xchar(tty, ch);
+               up_read(&tty->termios_rwsem);
                return 0;
        }
 
        if (tty_write_lock(tty, 0) < 0)
                return -ERESTARTSYS;
 
+       down_read(&tty->termios_rwsem);
        if (was_stopped)
                start_tty(tty);
        tty->ops->write(tty, &ch, 1);
        if (was_stopped)
                stop_tty(tty);
+       up_read(&tty->termios_rwsem);
        tty_write_unlock(tty);
        return 0;
 }