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>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/usb/serial/spcp8x5.c b/drivers/usb/serial/spcp8x5.c
index 283cf6b36b2c..1533d6e12238 100644
--- a/drivers/usb/serial/spcp8x5.c
+++ b/drivers/usb/serial/spcp8x5.c
@@ -755,7 +755,7 @@ static void spcp8x5_read_bulk_callback(struct urb *urb)
                 tty_flag = TTY_FRAME;
         dev_dbg(&port->dev, "tty_flag = %d\n", tty_flag);
 
-        tty = port->port.tty;
+        tty = tty_port_tty_get(&port->port);
         if (tty && urb->actual_length) {
                 tty_buffer_request_room(tty, urb->actual_length + 1);
                 /* overrun is special, not associated with a char */
@@ -765,6 +765,7 @@ static void spcp8x5_read_bulk_callback(struct urb *urb)
                         tty_insert_flip_char(tty, data[i], tty_flag);
                 tty_flip_buffer_push(tty);
         }
+        tty_kref_put(tty);
 
         /* Schedule the next read _if_ we are still open */
         if (port->port.count) {