static int this_tty(const void *t, struct file *file, unsigned fd)
{
	if (likely(file->f_op->read != tty_read))
		return 0;
	return file_tty(file) != t ? 0 : fd + 1;
}

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.