V4L/DVB:usbvideo:don't use part of buffer for USB transfer #4

The status[] is part of  uvc_device structure. We can't make sure
the address of status is at a cache-line boundary in all archs,so
status[] might share a cache-line with some fields in uvc_structure.
This can lead to some cache coherence issues(http://lwn.net/Articles/2265/).
Use dynamically allocated buffer instead.

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Acked-by: Laurent Pinchart <laurent.pinchart@skynet.be>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/media/video/uvc/uvcvideo.h b/drivers/media/video/uvc/uvcvideo.h
index bafe3406e305..9a6bc1aafb16 100644
--- a/drivers/media/video/uvc/uvcvideo.h
+++ b/drivers/media/video/uvc/uvcvideo.h
@@ -303,6 +303,8 @@ struct uvc_xu_control {
 #define UVC_MAX_FRAME_SIZE      (16*1024*1024)
 /* Maximum number of video buffers. */
 #define UVC_MAX_VIDEO_BUFFERS   32
+/* Maximum status buffer size in bytes of interrupt URB. */
+#define UVC_MAX_STATUS_SIZE     16
 
 #define UVC_CTRL_CONTROL_TIMEOUT        300
 #define UVC_CTRL_STREAMING_TIMEOUT      1000
@@ -634,7 +636,7 @@ struct uvc_device {
         /* Status Interrupt Endpoint */
         struct usb_host_endpoint *int_ep;
         struct urb *int_urb;
-        __u8 status[16];
+        __u8 *status;
         struct input_dev *input;
 
         /* Video Streaming interfaces */