cx25821: sanitize cx25821_get_audio_data() a bit

static int cx25821_get_audio_data(struct cx25821_dev *dev,

			   struct sram_channel *sram_ch)

{

	struct file *myfile;

	struct file *file;

	int frame_index_temp = dev->_audioframe_index;

	int i = 0;

	int line_size = AUDIO_LINE_SIZE;

	int frame_size = AUDIO_DATA_BUF_SZ;

	int frame_offset = frame_size * frame_index_temp;

	ssize_t vfs_read_retval = 0;

	char mybuf[line_size];

	char mybuf[AUDIO_LINE_SIZE];

	loff_t file_offset = dev->_audioframe_count * frame_size;

	loff_t pos;

	mm_segment_t old_fs;

	char *p = NULL;

	if (dev->_audiofile_status == END_OF_FILE)

		return 0;

	myfile = filp_open(dev->_audiofilename, O_RDONLY | O_LARGEFILE, 0);

	if (IS_ERR(myfile)) {

		const int open_errno = -PTR_ERR(myfile);

		pr_err("%s(): ERROR opening file(%s) with errno = %d!\n",

		       __func__, dev->_audiofilename, open_errno);

		return PTR_ERR(myfile);

	} else {

		if (!(myfile->f_op)) {

			pr_err("%s(): File has no file operations registered!\n",

				__func__);

			filp_close(myfile, NULL);

			return -EIO;

		}

		if (!myfile->f_op->read) {

			pr_err("%s(): File has no READ operations registered!\n",

				__func__);

			filp_close(myfile, NULL);

			return -EIO;

	file = filp_open(dev->_audiofilename, O_RDONLY | O_LARGEFILE, 0);

	if (IS_ERR(file)) {

		pr_err("%s(): ERROR opening file(%s) with errno = %ld!\n",

		       __func__, dev->_audiofilename, -PTR_ERR(file));

		return PTR_ERR(file);

	}

		pos = myfile->f_pos;

		old_fs = get_fs();

		set_fs(KERNEL_DS);

	if (dev->_audiodata_buf_virt_addr)

		p = (char *)dev->_audiodata_buf_virt_addr + frame_offset;

	for (i = 0; i < dev->_audio_lines_count; i++) {

			pos = file_offset;

			vfs_read_retval = vfs_read(myfile, mybuf, line_size,

									&pos);

			if (vfs_read_retval > 0 && vfs_read_retval == line_size

			    && dev->_audiodata_buf_virt_addr != NULL) {

				memcpy((void *)(dev->_audiodata_buf_virt_addr +

						frame_offset / 4), mybuf,

					vfs_read_retval);

			}

			file_offset += vfs_read_retval;

			frame_offset += vfs_read_retval;

			if (vfs_read_retval < line_size) {

		int n = kernel_read(file, file_offset, mybuf, AUDIO_LINE_SIZE);

		if (n < AUDIO_LINE_SIZE) {

			pr_info("Done: exit %s() since no more bytes to read from Audio file\n",

				__func__);

				break;

			dev->_audiofile_status = END_OF_FILE;

			fput(file);

			return 0;

		}

		dev->_audiofile_status = IN_PROGRESS;

		if (p) {

			memcpy(p, mybuf, n);

			p += n;

		}

		if (i > 0)

			dev->_audioframe_count++;

		dev->_audiofile_status = (vfs_read_retval == line_size) ?

						IN_PROGRESS : END_OF_FILE;

		set_fs(old_fs);

		filp_close(myfile, NULL);

		file_offset += n;

	}

	dev->_audioframe_count++;

	fput(file);

	return 0;

}