[PATCH] xhci-ring: process bulk set actual_length only when not COMP_STOP_INVAL

[xiao jin <jin.xiao@intel.com>]

When suspend, some urb is put into cancelled_td_list.
process_bulk_intr_td may process the last trb as below:
xhci_transfer_event.transfer_len = 0
xhci_transfer_event.trb_comp_code = 27
urb.transfer_buffer_length = 1024

trb_comp_code is COMP_STOP_INVAL, it should be taken as
invalid urb and discarded, but urb actual_length still is
calculated as transfer_buffer_length. When handling Stop
Endpoint Command completion, the urb in cancelled_td_list
is transferred to upper layer(cdc-acm for example). The
content of urb transfer_buffer is the overlay of previous
two read transfer_buffer. It makes upper layer process wrong
buffer.

This patch is to set actual_length as transfer_buffer_length
only if trb_comp_code is not COMP_STOP_INVAL when
process_bulk_intr_td.

Signed-off-by: xiao jin <jin.xiao@intel.com>
---
 drivers/usb/host/xhci-ring.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 6bfbd80..c9a8863 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -2319,8 +2319,11 @@ static int process_bulk_intr_td(struct xhci_hcd *xhci, struct xhci_td *td,
 					*status = 0;
 			}
 		} else {
-			td->urb->actual_length =
-				td->urb->transfer_buffer_length;
+			if (trb_comp_code != COMP_STOP_INVAL)
+				td->urb->actual_length =
+					td->urb->transfer_buffer_length;
+			else
+				td->urb->actual_length = 0;
 			/* Ignore a short packet completion if the
 			 * untransferred length was zero.
 			 */
-- 
1.7.0.4