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, 4 insertions, 3 deletions

diff --git a/drivers/usb/serial/mos7840.c b/drivers/usb/serial/mos7840.c
index 09d82062b973..60543d79ef56 100644
--- a/drivers/usb/serial/mos7840.c
+++ b/drivers/usb/serial/mos7840.c
@@ -709,12 +709,13 @@ static void mos7840_bulk_in_callback(struct urb *urb)
         dbg("%s", "Entering ........... \n");
 
         if (urb->actual_length) {
-                tty = mos7840_port->port->port.tty;
+                tty = tty_port_tty_get(&mos7840_port->port->port);
                 if (tty) {
                         tty_buffer_request_room(tty, urb->actual_length);
                         tty_insert_flip_string(tty, data, urb->actual_length);
                         dbg(" %s \n", data);
                         tty_flip_buffer_push(tty);
+                        tty_kref_put(tty);
                 }
                 mos7840_port->icount.rx += urb->actual_length;
                 smp_wmb();
@@ -773,10 +774,10 @@ static void mos7840_bulk_out_data_callback(struct urb *urb)
 
         dbg("%s \n", "Entering .........");
 
-        tty = mos7840_port->port->port.tty;
-
+        tty = tty_port_tty_get(&mos7840_port->port->port);
         if (tty && mos7840_port->open)
                 tty_wakeup(tty);
+        tty_kref_put(tty);
 
 }