tty: Preset lock subclass for nested tty locks

Eliminate the requirement of specifying the tty lock nesting at
lock time; instead, set the lock subclass for slave ptys at pty
install (normal ttys and master ptys use subclass 0).

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index bdb8fd1a2026..11db7dc8676b 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -399,6 +399,8 @@ static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
         if (!o_tty)
                 goto err_put_module;
 
+        tty_set_lock_subclass(o_tty);
+
         if (legacy) {
                 /* We always use new tty termios data so we can do this
                    the easy way .. */