xhci: fix reporting of 0-sized URBs in control endpoint
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. Cc: <stable@vger.kernel.org> 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>
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@ -1946,7 +1946,7 @@ static int process_ctrl_td(struct xhci_hcd *xhci, struct xhci_td *td,
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if (event_trb != ep_ring->dequeue) {
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/* The event was for the status stage */
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if (event_trb == td->last_trb) {
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if (td->urb->actual_length != 0) {
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if (td->urb_length_set) {
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/* Don't overwrite a previously set error code
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*/
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if ((*status == -EINPROGRESS || *status == 0) &&
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@ -1960,7 +1960,13 @@ static int process_ctrl_td(struct xhci_hcd *xhci, struct xhci_td *td,
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td->urb->transfer_buffer_length;
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}
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} else {
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/* Maybe the event was for the data stage? */
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/*
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* Maybe the event was for the data stage? If so, update
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* already the actual_length of the URB and flag it as
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* set, so that it is not overwritten in the event for
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* the last TRB.
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*/
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td->urb_length_set = true;
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td->urb->actual_length =
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td->urb->transfer_buffer_length -
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EVENT_TRB_LEN(le32_to_cpu(event->transfer_len));
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@ -1,3 +1,4 @@
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/*
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* xHCI host controller driver
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*
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@ -1291,6 +1292,8 @@ struct xhci_td {
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struct xhci_segment *start_seg;
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union xhci_trb *first_trb;
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union xhci_trb *last_trb;
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/* actual_length of the URB has already been set */
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bool urb_length_set;
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};
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/* xHCI command default timeout value */
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