Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753944AbbEEBlq (ORCPT ); Mon, 4 May 2015 21:41:46 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:50849 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752496AbbEEBWq (ORCPT ); Mon, 4 May 2015 21:22:46 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Greg Kroah-Hartman" , "Aleksander Morgado" , "Mathias Nyman" Date: Tue, 05 May 2015 02:16:39 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 086/221] xhci: fix reporting of 0-sized URBs in control endpoint In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3164 Lines: 84 3.2.69-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Aleksander Morgado 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 Signed-off-by: Mathias Nyman Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ben Hutchings --- drivers/usb/host/xhci-ring.c | 10 ++++++++-- drivers/usb/host/xhci.h | 3 +++ 2 files changed, 11 insertions(+), 2 deletions(-) --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -1980,7 +1980,7 @@ static int process_ctrl_td(struct xhci_h 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) && @@ -1994,7 +1994,13 @@ static int process_ctrl_td(struct xhci_h 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)); --- a/drivers/usb/host/xhci.h +++ b/drivers/usb/host/xhci.h @@ -1,3 +1,4 @@ + /* * xHCI host controller driver * @@ -1256,6 +1257,8 @@ struct xhci_td { 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 */ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/