cx25821: sanitize cx25821_get_audio_data() a bit

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

drivers/media/pci/cx25821/cx25821-audio-upstream.c

@@ -259,79 +259,46 @@ void cx25821_free_mem_upstream_audio(struct cx25821_dev *dev)
 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;
 }