[PATCH 4.2.y-ckt 056/206] usb: misc: usbtest: fix pattern tests for scatterlists.

[Kamal Mostafa <kamal@canonical.com>]

4.2.8-ckt12 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Mathias Nyman <mathias.nyman@linux.intel.com>

commit cdc77c82a8286b1181b81b6e5ef60c8e83ded7bc upstream.

The current implemenentation restart the sent pattern for each entry in
the sg list. The receiving end expects a continuous pattern, and test
will fail unless scatterilst entries happen to be aligned with the
pattern

Fix this by calculating the pattern byte based on total sent size
instead of just the current sg entry.

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Fixes: 8b5249019352 ("[PATCH] USB: usbtest: scatterlist OUT data pattern testing")
Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 drivers/usb/misc/usbtest.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/misc/usbtest.c b/drivers/usb/misc/usbtest.c
index 46bb062..bbddc44 100644
--- a/drivers/usb/misc/usbtest.c
+++ b/drivers/usb/misc/usbtest.c
@@ -492,6 +492,7 @@ static struct scatterlist *
 alloc_sglist(int nents, int max, int vary, struct usbtest_dev *dev, int pipe)
 {
 	struct scatterlist	*sg;
+	unsigned int		n_size = 0;
 	unsigned		i;
 	unsigned		size = max;
 	unsigned		maxpacket =
@@ -524,7 +525,8 @@ alloc_sglist(int nents, int max, int vary, struct usbtest_dev *dev, int pipe)
 			break;
 		case 1:
 			for (j = 0; j < size; j++)
-				*buf++ = (u8) ((j % maxpacket) % 63);
+				*buf++ = (u8) (((j + n_size) % maxpacket) % 63);
+			n_size += size;
 			break;
 		}
 
-- 
2.7.4