tty: usb-serial krefs

Use kref in the USB serial drivers so that we don't free tty structures
from under the URB receive handlers as has historically been the case if
you were unlucky. This also gives us a framework for general tty drivers to
use tty_port objects and refcount.

Contains two err->dev_err changes merged together to fix clashes in the
-next tree.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/usb/serial/kl5kusb105.c b/drivers/usb/serial/kl5kusb105.c
index b84dddc..ff3a07f 100644
--- a/drivers/usb/serial/kl5kusb105.c
+++ b/drivers/usb/serial/kl5kusb105.c
@@ -658,7 +658,7 @@
 	} else {
 		int bytes_sent = ((__u8 *) data)[0] +
 				 ((unsigned int) ((__u8 *) data)[1] << 8);
-		tty = port->port.tty;
+		tty = tty_port_tty_get(&port->port);
 		/* we should immediately resubmit the URB, before attempting
 		 * to pass the data on to the tty layer. But that needs locking
 		 * against re-entry an then mixed-up data because of
@@ -679,6 +679,7 @@
 		tty_buffer_request_room(tty, bytes_sent);
 		tty_insert_flip_string(tty, data + 2, bytes_sent);
 		tty_flip_buffer_push(tty);
+		tty_kref_put(tty);
 
 		/* again lockless, but debug info only */
 		priv->bytes_in += bytes_sent;