V4L/DVB (9991): gspca - main: Check if a buffer has been queued on streamon.

Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/gspca/gspca.c

@@ -1226,7 +1226,8 @@ static int vidioc_streamon(struct file *file, void *priv,
 		ret = -ENODEV;
 		goto out;
 	}
-	if (gspca_dev->nframes == 0) {
+	if (gspca_dev->nframes == 0
+	    || !(gspca_dev->frame[0].v4l2_buf.flags & V4L2_BUF_FLAG_QUEUED)) {
 		ret = -EINVAL;
 		goto out;
 	}