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>

1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 9bf01a5efc84..26e015c39a31 100644
--- 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);
 }