control_buf
struct control_buf *ctrl;
kfree(uvc->control_buf);
uvc->control_buf = kmalloc(UVC_MAX_REQUEST_SIZE, GFP_KERNEL);
if (uvc->control_req == NULL || uvc->control_buf == NULL) {
uvc->control_req->buf = uvc->control_buf;
kfree(uvc->control_buf);
void *control_buf;
memset(control_buf, 0, sizeof(control_buf));
char control_buf[CMSG_SPACE(sizeof(uint64_t))];
.msg_control = control_buf,
.msg_controllen = sizeof(control_buf),