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/generic.c b/drivers/usb/serial/generic.c
index fe84c88..814909f 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -330,7 +330,7 @@ static void resubmit_read_urb(struct usb_serial_port *port, gfp_t mem_flags)
 static void flush_and_resubmit_read_urb(struct usb_serial_port *port)
 {
 	struct urb *urb = port->read_urb;
-	struct tty_struct *tty = port->port.tty;
+	struct tty_struct *tty = tty_port_tty_get(&port->port);
 	int room;
 
 	/* Push data to tty */
@@ -341,6 +341,7 @@ static void flush_and_resubmit_read_urb(struct usb_serial_port *port)
 			tty_flip_buffer_push(tty);
 		}
 	}
+	tty_kref_put(tty);
 
 	resubmit_read_urb(port, GFP_ATOMIC);
 }