TTY: check if tty->port is assigned

And if not, complain loudly. None in-kernel module should trigger
that, but let us find out for sure. On the other hand, all the
out-of-tree modules will hit that. Give them some time (maybe one
release) to catch up.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 28c3e869ebba..41e42f13a214 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1415,6 +1415,10 @@ struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
         if (!tty->port)
                 tty->port = driver->ports[idx];
 
+        WARN_RATELIMIT(!tty->port,
+                        "%s: %s driver does not set tty->port. This will crash the kernel later. Fix the driver!\n",
+                        __func__, tty->driver->name);
+
         /*
          * Structures all installed ... call the ldisc open routines.
          * If we fail here just call release_tty to clean up.  No need