serdev: ttyport: fix tty locking in close

Make sure to hold the tty lock as required when calling tty-driver
close() (e.g. to avoid racing with hangup()).

Note that the serport active flag is currently set under the lock at
controller open, but really isn't protected by it.

Fixes: cd6484e1830b ("serdev: Introduce new bus for serial attached devices")
Signed-off-by: Johan Hovold <johan@kernel.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serdev/serdev-ttyport.c b/drivers/tty/serdev/serdev-ttyport.c
index 12cb913..247788a 100644 (file)
--- a/drivers/tty/serdev/serdev-ttyport.c
+++ b/drivers/tty/serdev/serdev-ttyport.c
@@ -154,8 +154,10 @@ static void ttyport_close(struct serdev_controller *ctrl)
 
        clear_bit(SERPORT_ACTIVE, &serport->flags);
 
+       tty_lock(tty);
        if (tty->ops->close)
                tty->ops->close(tty, NULL);
+       tty_unlock(tty);
 
        tty_release_struct(tty, serport->tty_idx);
 }