USB: xHCI: update ring dequeue pointer when process missed tds

This patch fixes a isoc transfer bug reported by Sander Eikelenboom.
When ep->skip is set, endpoint ring dequeue pointer should be updated
when processed every missed td. Although ring dequeue pointer will also
be updated when ep->skip is clear, leave it intact during missed tds
processing may cause two issues:

1). If the very next valid transfer following missed tds is a short
transfer, its actual_length will be miscalculated;
2). If there are too many missed tds during transfer, new inserted tds
may found the transfer ring full and urb enqueue fails.

Reported-by: Sander Eikelenboom <linux@eikelenboom.it>
Tested-by: Sander Eikelenboom <linux@eikelenboom.it>
Signed-off-by: Andiry Xu <andiry.xu@amd.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 2f19f3a..48e60d1 100644 (file)
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -1551,6 +1551,10 @@ static int process_isoc_td(struct xhci_hcd *xhci, struct xhci_td *td,
        /* calc actual length */
        if (ep->skip) {
                td->urb->iso_frame_desc[idx].actual_length = 0;
+               /* Update ring dequeue pointer */
+               while (ep_ring->dequeue != td->last_trb)
+                       inc_deq(xhci, ep_ring, false);
+               inc_deq(xhci, ep_ring, false);
                return finish_td(xhci, td, event_trb, event, ep, status, true);
        }