4.4-stable review patch. If anyone has any objections, please let me know.
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From: Alan Stern stern@rowland.harvard.edu
commit 2ef47001b3ee3ded579b7532ebdcf8680e4d8c54 upstream.
The USB kerneldoc says that the actual_length field "is read in non-iso completion functions", but the usbfs driver uses it for all URB types in processcompl(). Since not all of the host controller drivers set actual_length for isochronous URBs, programs using usbfs with some host controllers don't work properly. For example, Minas reports that a USB camera controlled by libusb doesn't work properly with a dwc2 controller.
It doesn't seem worthwhile to change the HCDs and the documentation, since the in-kernel USB class drivers evidently don't rely on actual_length for isochronous transfers. The easiest solution is for usbfs to calculate the actual_length value for itself, by adding up the lengths of the individual packets in an isochronous transfer.
Signed-off-by: Alan Stern stern@rowland.harvard.edu CC: Minas Harutyunyan Minas.Harutyunyan@synopsys.com Reported-and-tested-by: wlf wulf@rock-chips.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/usb/core/devio.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
--- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -1653,6 +1653,18 @@ static int proc_unlinkurb(struct usb_dev return 0; }
+static void compute_isochronous_actual_length(struct urb *urb) +{ + unsigned int i; + + if (urb->number_of_packets > 0) { + urb->actual_length = 0; + for (i = 0; i < urb->number_of_packets; i++) + urb->actual_length += + urb->iso_frame_desc[i].actual_length; + } +} + static int processcompl(struct async *as, void __user * __user *arg) { struct urb *urb = as->urb; @@ -1660,6 +1672,7 @@ static int processcompl(struct async *as void __user *addr = as->userurb; unsigned int i;
+ compute_isochronous_actual_length(urb); if (as->userbuffer && urb->actual_length) { if (copy_urb_data_to_user(as->userbuffer, urb)) goto err_out; @@ -1829,6 +1842,7 @@ static int processcompl_compat(struct as void __user *addr = as->userurb; unsigned int i;
+ compute_isochronous_actual_length(urb); if (as->userbuffer && urb->actual_length) { if (copy_urb_data_to_user(as->userbuffer, urb)) return -EFAULT;