linux-kernel - [PATCH 3.19.y-ckt 118/155] xhci: don't finish a TD if we get a short transfer event mid TD

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Date:	Thu, 12 Nov 2015 15:17:52 -0800
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Mathias Nyman <mathias.nyman@...ux.intel.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.19.y-ckt 118/155] xhci: don't finish a TD if we get a short transfer event mid TD

3.19.8-ckt10 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mathias Nyman <mathias.nyman@...ux.intel.com>

commit e210c422b6fdd2dc123bedc588f399aefd8bf9de upstream.

If the difference is big enough between the bytes asked and received
in a bulk transfer we can get a short transfer event pointing to a TRB in
the middle of the TD. We don't want to handle the TD yet as we will anyway
receive a new event for the last TRB in the TD.

Hold off from finishing the TD and removing it from the list until we
receive an event for the last TRB in the TD

Signed-off-by: Mathias Nyman <mathias.nyman@...ux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 drivers/usb/host/xhci-ring.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 06c247e..66bc627 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -2156,6 +2156,10 @@ static int process_bulk_intr_td(struct xhci_hcd *xhci, struct xhci_td *td,
 				EVENT_TRB_LEN(le32_to_cpu(event->transfer_len)));
 	/* Fast path - was this the last TRB in the TD for this URB? */
 	if (event_trb == td->last_trb) {
+		if (td->urb_length_set && trb_comp_code == COMP_SHORT_TX)
+			return finish_td(xhci, td, event_trb, event, ep,
+					 status, false);
+
 		if (EVENT_TRB_LEN(le32_to_cpu(event->transfer_len)) != 0) {
 			td->urb->actual_length =
 				td->urb->transfer_buffer_length -
@@ -2207,6 +2211,12 @@ static int process_bulk_intr_td(struct xhci_hcd *xhci, struct xhci_td *td,
 			td->urb->actual_length +=
 				TRB_LEN(le32_to_cpu(cur_trb->generic.field[2])) -
 				EVENT_TRB_LEN(le32_to_cpu(event->transfer_len));
+
+		if (trb_comp_code == COMP_SHORT_TX) {
+			xhci_dbg(xhci, "mid bulk/intr SP, wait for last TRB event\n");
+			td->urb_length_set = true;
+			return 0;
+		}
 	}
 
 	return finish_td(xhci, td, event_trb, event, ep, status, false);
-- 
1.9.1

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