xhci: fix reporting of 0-sized URBs in control endpoint
commit 45ba2154d12fc43b70312198ec47085f10be801a upstream.
When a control transfer has a short data stage, the xHCI controller generates
two transfer events: a COMP_SHORT_TX event that specifies the untransferred
amount, and a COMP_SUCCESS event. But when the data stage is not short, only the
COMP_SUCCESS event occurs. Therefore, xhci-hcd must set urb->actual_length to
urb->transfer_buffer_length while processing the COMP_SUCCESS event, unless
urb->actual_length was set already by a previous COMP_SHORT_TX event.
The driver checks this by seeing whether urb->actual_length == 0, but this alone
is the wrong test, as it is entirely possible for a short transfer to have an
urb->actual_length = 0.
This patch changes the xhci driver to rely on a new td->urb_length_set flag,
which is set to true when a COMP_SHORT_TX event is received and the URB length
updated at that stage.
This fixes a bug which affected the HSO plugin, which relies on URBs with
urb->actual_length == 0 to halt re-submitting the RX URB in the control
endpoint.
Signed-off-by: Aleksander Morgado <aleksander@aleksander.es>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index bc021e5..34a96ec 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -2032,7 +2032,7 @@
if (event_trb != ep_ring->dequeue) {
/* The event was for the status stage */
if (event_trb == td->last_trb) {
- if (td->urb->actual_length != 0) {
+ if (td->urb_length_set) {
/* Don't overwrite a previously set error code
*/
if ((*status == -EINPROGRESS || *status == 0) &&
@@ -2046,7 +2046,13 @@
td->urb->transfer_buffer_length;
}
} else {
- /* Maybe the event was for the data stage? */
+ /*
+ * Maybe the event was for the data stage? If so, update
+ * already the actual_length of the URB and flag it as
+ * set, so that it is not overwritten in the event for
+ * the last TRB.
+ */
+ td->urb_length_set = true;
td->urb->actual_length =
td->urb->transfer_buffer_length -
EVENT_TRB_LEN(le32_to_cpu(event->transfer_len));
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 5f02794..749791d 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1,3 +1,4 @@
+
/*
* xHCI host controller driver
*
@@ -1253,6 +1254,8 @@
struct xhci_segment *start_seg;
union xhci_trb *first_trb;
union xhci_trb *last_trb;
+ /* actual_length of the URB has already been set */
+ bool urb_length_set;
};
/* xHCI command default timeout value */
