patch "USB: usbfs: compute urb->actual_length for isochronous" added to usb-next

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    USB: usbfs: compute urb->actual_length for isochronous

to my usb git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-next branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will also be merged in the next major kernel release
during the merge window.

If you have any questions about this process, please let me know.


>From 2ef47001b3ee3ded579b7532ebdcf8680e4d8c54 Mon Sep 17 00:00:00 2001
From: Alan Stern <stern@rowland.harvard.edu>
Date: Wed, 8 Nov 2017 12:23:17 -0500
Subject: USB: usbfs: compute urb->actual_length for isochronous

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>
CC: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/core/devio.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index c3aaafc25a04..2edb4e7b2ab8 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -1820,6 +1820,18 @@ static int proc_unlinkurb(struct usb_dev_state *ps, void __user *arg)
 	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;
@@ -1827,6 +1839,7 @@ static int processcompl(struct async *as, void __user * __user *arg)
 	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;
@@ -1995,6 +2008,7 @@ static int processcompl_compat(struct async *as, void __user * __user *arg)
 	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;
-- 
2.15.0