vhost-scsi: Always access vq->private_data under vq mutex

	int head, ret;

	u8 target;

	mutex_lock(&vq->mutex);

	/*

	 * We can handle the vq only after the endpoint is setup by calling the

	 * VHOST_SCSI_SET_ENDPOINT ioctl.

	 *

	 * TODO: Check that we are running from vhost_worker which acts

	 * as read-side critical section for vhost kind of RCU.

	 * See the comments in struct vhost_virtqueue in drivers/vhost/vhost.h

	 */

	vs_tpg = rcu_dereference_check(vq->private_data, 1);

	vs_tpg = vq->private_data;

	if (!vs_tpg)

		return;

		goto out;

	mutex_lock(&vq->mutex);

	vhost_disable_notify(&vs->dev, vq);

	for (;;) {

	vhost_scsi_free_cmd(cmd);

err_cmd:

	vhost_scsi_send_bad_target(vs, vq, head, out);

out:

	mutex_unlock(&vq->mutex);

}