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| author | Aleksander Morgado <aleksander@aleksander.es> | 2015-03-06 17:14:21 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-03-18 13:31:29 +0100 |
| commit | 8ddb85838179cb34f92195182fbd1a5c7d1173c4 (patch) | |
| tree | 04fe44c965b1c80ddbf31837145dbed472e5187e | |
| parent | 7f5d3228923fcec697cfc0d563eab0a690fac2b6 (diff) | |
| download | lwn-8ddb85838179cb34f92195182fbd1a5c7d1173c4.tar.gz lwn-8ddb85838179cb34f92195182fbd1a5c7d1173c4.zip | |
xhci: fix reporting of 0-sized URBs in control endpoint
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 <aleksander@aleksander.es>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/usb/host/xhci-ring.c | 10 | ||||
| -rw-r--r-- | 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 faa8b98954d9..a95eee8ddc38 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -2133,7 +2133,7 @@ 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) && @@ -2147,7 +2147,13 @@ 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 0783b6191d3e..7225dd242bfa 100644 --- a/drivers/usb/host/xhci.h +++ b/drivers/usb/host/xhci.h @@ -1,3 +1,4 @@ + /* * xHCI host controller driver * @@ -1290,6 +1291,8 @@ 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 */ |