static void unlock_fs(struct mapped_device *md)
{
	if (!test_bit(DMF_FROZEN, &md->flags))
		return;

	thaw_bdev(md->bdev, md->frozen_sb);
	md->frozen_sb = NULL;
	clear_bit(DMF_FROZEN, &md->flags);
}

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.