USB: fix errornous assumption in the usb serial framework revealed by iuu_phoenix

the iuu_phoenix driver submits another URB from a completion handler.
This dictates a certain order of calls to usb_kill_urb() in kill_traffic().
As other drivers may do it the other way round, we need to use both
orders in kill_traffic().
This patch does so and should be merged before iuu_phoenix is merged.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 9bf01a5efc84adaaec0145ca24076421b64db558..26e015c39a31acebed24d0a1f72285c36fe97e09 100644 (file)
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -578,6 +578,17 @@ static void kill_traffic(struct usb_serial_port *port)
 {
        usb_kill_urb(port->read_urb);
        usb_kill_urb(port->write_urb);
+       /*
+        * This is tricky.
+        * Some drivers submit the read_urb in the
+        * handler for the write_urb or vice versa
+        * this order determines the order in which
+        * usb_kill_urb() must be used to reliably
+        * kill the URBs. As it is unknown here,
+        * both orders must be used in turn.
+        * The call below is not redundant.
+        */
+       usb_kill_urb(port->read_urb);
        usb_kill_urb(port->interrupt_in_urb);
        usb_kill_urb(port->interrupt_out_urb);
 }