inline void __blk_mq_end_request(struct request *rq, int error)
{
	blk_account_io_done(rq);

	if (rq->end_io) {
		rq->end_io(rq, error);
	} else {
		if (unlikely(blk_bidi_rq(rq)))
			blk_mq_free_request(rq->next_rq);
		blk_mq_free_request(rq);
	}
}

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.