tty: Fix leak in ti-usb

If the ti-usb adapter returns an zero data length frame (which happens)
then we leak a kref.  Found by Christoph Mair <christoph.mair@gmail.com>
who proposed a patch.  The patch here is different as Christoph's patch
didn't work for the case where tty = NULL and data arrived but Christoph
did all the hard work chasing it down.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 14 insertions, 12 deletions

diff --git a/drivers/usb/serial/ti_usb_3410_5052.c b/drivers/usb/serial/ti_usb_3410_5052.c
index 2620bf6fe5e1..9c4c700c7cc6 100644
--- a/drivers/usb/serial/ti_usb_3410_5052.c
+++ b/drivers/usb/serial/ti_usb_3410_5052.c
@@ -1215,20 +1215,22 @@ static void ti_bulk_in_callback(struct urb *urb)
         }
 
         tty = tty_port_tty_get(&port->port);
-        if (tty && urb->actual_length) {
-                usb_serial_debug_data(debug, dev, __func__,
-                        urb->actual_length, urb->transfer_buffer);
-
-                if (!tport->tp_is_open)
-                        dbg("%s - port closed, dropping data", __func__);
-                else
-                        ti_recv(&urb->dev->dev, tty,
+        if (tty) {
+                if (urb->actual_length) {
+                        usb_serial_debug_data(debug, dev, __func__,
+                                urb->actual_length, urb->transfer_buffer);
+
+                        if (!tport->tp_is_open)
+                                dbg("%s - port closed, dropping data",
+                                        __func__);
+                        else
+                                ti_recv(&urb->dev->dev, tty,
                                                 urb->transfer_buffer,
                                                 urb->actual_length);
-
-                spin_lock(&tport->tp_lock);
-                tport->tp_icount.rx += urb->actual_length;
-                spin_unlock(&tport->tp_lock);
+                        spin_lock(&tport->tp_lock);
+                        tport->tp_icount.rx += urb->actual_length;
+                        spin_unlock(&tport->tp_lock);
+                }
                 tty_kref_put(tty);
         }