static void end_io_acct(struct dm_io *io)
{
	struct mapped_device *md = io->md;
	struct bio *bio = io->bio;
	unsigned long duration = jiffies - io->start_time;
	int pending;
	int rw = bio_data_dir(bio);

	generic_end_io_acct(md->queue, rw, &dm_disk(md)->part0, io->start_time);

	if (unlikely(dm_stats_used(&md->stats)))
		dm_stats_account_io(&md->stats, bio_data_dir(bio),
				    bio->bi_iter.bi_sector, bio_sectors(bio),
				    true, duration, &io->stats_aux);

	/*
	 * After this is decremented the bio must not be touched if it is
	 * a flush.
	 */
	pending = atomic_dec_return(&md->pending[rw]);
	atomic_set(&dm_disk(md)->part0.in_flight[rw], pending);
	pending += atomic_read(&md->pending[rw^0x1]);

	/* nudge anyone waiting on suspend queue */
	if (!pending)
		wake_up(&md->wait);
}

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.