3.18-stable review patch. If anyone has any objections, please let me know.
------------------
From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxxx>
CC: Minas Harutyunyan <Minas.Harutyunyan@xxxxxxxxxxxx>
Reported-and-tested-by: wlf <wulf@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/core/devio.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -1649,6 +1649,18 @@ 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;
@@ -1656,6 +1668,7 @@ 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;
@@ -1825,6 +1838,7 @@ 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;