static void ath_tx_update_baw(struct ath_softc *sc, struct ath_atx_tid *tid,
			      int seqno)
{
	int index, cindex;

	index  = ATH_BA_INDEX(tid->seq_start, seqno);
	cindex = (tid->baw_head + index) & (ATH_TID_MAX_BUFS - 1);

	__clear_bit(cindex, tid->tx_buf);

	while (tid->baw_head != tid->baw_tail && !test_bit(tid->baw_head, tid->tx_buf)) {
		INCR(tid->seq_start, IEEE80211_SEQ_MAX);
		INCR(tid->baw_head, ATH_TID_MAX_BUFS);
		if (tid->bar_index >= 0)
			tid->bar_index--;
	}
}

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.