V4L/DVB (10794): v4l2: Move code to zero querybuf output struct to v4l2_ioctl

For VIDIOC_QUERYBUF only the first two fields, size and type, are used as
input.  The rest can be filled in by the driver as output.  Most drivers do
not actually use all the field and unused ones should be zeroed out.  Some
drivers have code to do this and some drivers should but don't.  So put
some zero out code in v4l2_ioctl so that all drivers using that system get
it.

The drivers that have zeroing code get that code removed.

Some drivers checked that the type field was valid, but v4l2_ioctl already
does this so those checks can be removed as well.

Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/meye.c

@@ -1446,10 +1446,6 @@ static int vidioc_querybuf(struct file *file, void *fh, struct v4l2_buffer *buf)
 	if (index < 0 || index >= gbuffers)
 		return -EINVAL;
 
-	memset(buf, 0, sizeof(*buf));
-
-	buf->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
-	buf->index = index;
 	buf->bytesused = meye.grab_buffer[index].size;
 	buf->flags = V4L2_BUF_FLAG_MAPPED;
 

drivers/media/video/stk-webcam.c

@@ -1139,16 +1139,10 @@ static int stk_vidioc_reqbufs(struct file *filp,
 static int stk_vidioc_querybuf(struct file *filp,
 		void *priv, struct v4l2_buffer *buf)
 {
-	int index;
 	struct stk_camera *dev = priv;
 	struct stk_sio_buffer *sbuf;
 
-	if (buf->type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
+	if (buf->index < 0 || buf->index >= dev->n_sbufs)
-		return -EINVAL;
-
-	index = buf->index;
-
-	if (index < 0 || index >= dev->n_sbufs)
 		return -EINVAL;
 	sbuf = dev->sio_bufs + buf->index;
 	*buf = sbuf->v4lbuf;

drivers/media/video/usbvision/usbvision-video.c

@@ -788,9 +788,6 @@ static int vidioc_querybuf (struct file *file,
 
 	/* FIXME : must control
 	   that buffers are mapped (VIDIOC_REQBUFS has been called) */
-	if(vb->type != V4L2_CAP_VIDEO_CAPTURE) {
-		return -EINVAL;
-	}
 	if(vb->index>=usbvision->num_frames)  {
 		return -EINVAL;
 	}

drivers/media/video/v4l2-ioctl.c

@@ -969,6 +969,11 @@ static long __video_do_ioctl(struct file *file,
 		if (ret)
 			break;
 
+		/* Zero out all fields starting with bytesysed, which is
+		 * everything but index and type.  */
+		memset(0, &p->bytesused,
+		       sizeof(*p) - offsetof(typeof(*p), bytesused));
+
 		ret = ops->vidioc_querybuf(file, fh, p);
 		if (!ret)
 			dbgbuf(cmd, vfd, p);

drivers/media/video/zoran/zoran_driver.c

@@ -2498,12 +2498,7 @@ static int zoran_querybuf(struct file *file, void *__fh, struct v4l2_buffer *buf
 {
 	struct zoran_fh *fh = __fh;
 	struct zoran *zr = fh->zr;
-	__u32 type = buf->type;
+	int res;
-	int index = buf->index, res;
-
-	memset(buf, 0, sizeof(*buf));
-	buf->type = type;
-	buf->index = index;
 
 	mutex_lock(&zr->resource_lock);
 	res = zoran_v4l2_buffer_status(file, buf, buf->index);