From 45ba2154d12fc43b70312198ec47085f10be801a Mon Sep 17 00:00:00 2001 From: Aleksander Morgado Date: Fri, 6 Mar 2015 17:14:21 +0200 Subject: [PATCH] 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: Signed-off-by: Aleksander Morgado Signed-off-by: Mathias Nyman Signed-off-by: Greg Kroah-Hartman --- drivers/usb/host/xhci-ring.c | 10 ++++++++-- drivers/usb/host/xhci.h | 3 +++ 2 files changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index b46b5b98a943..5fb66db89e05 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -1946,7 +1946,7 @@ static int process_ctrl_td(struct xhci_hcd *xhci, struct xhci_td *td, 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) && @@ -1960,7 +1960,13 @@ static int process_ctrl_td(struct xhci_hcd *xhci, struct xhci_td *td, 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 3b97f0582155..d0663931e5ba 100644 --- a/drivers/usb/host/xhci.h +++ b/drivers/usb/host/xhci.h @@ -1,3 +1,4 @@ + /* * xHCI host controller driver * @@ -1291,6 +1292,8 @@ 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 */ -- 2.20.1