1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/isdn/gigaset/interface.c b/drivers/isdn/gigaset/interface.c
index f13de20947e0..eb50f3dab5f7 100644
--- a/drivers/isdn/gigaset/interface.c
+++ b/drivers/isdn/gigaset/interface.c
@@ -615,6 +615,8 @@ void gigaset_if_init(struct cardstate *cs)
                 return;
 
         tasklet_init(&cs->if_wake_tasklet, &if_wake, (unsigned long) cs);
+
+        mutex_lock(&cs->mutex);
         cs->tty_dev = tty_register_device(drv->tty, cs->minor_index, NULL);
 
         if (!IS_ERR(cs->tty_dev))
@@ -623,6 +625,7 @@ void gigaset_if_init(struct cardstate *cs)
                 warn("could not register device to the tty subsystem");
                 cs->tty_dev = NULL;
         }
+        mutex_unlock(&cs->mutex);
 }
 
 void gigaset_if_free(struct cardstate *cs)