[PATCH 4.16 27/47] iio:buffer: make length types match kfifo types

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Martin Kelly <mkelly@xxxxxxxx>

commit c043ec1ca5baae63726aae32abbe003192bc6eec upstream.

Currently, we use int for buffer length and bytes_per_datum. However,
kfifo uses unsigned int for length and size_t for element size. We need
to make sure these matches or we will have bugs related to overflow (in
the range between INT_MAX and UINT_MAX for length, for example).

In addition, set_bytes_per_datum uses size_t while bytes_per_datum is an
int, which would cause bugs for large values of bytes_per_datum.

Change buffer length to use unsigned int and bytes_per_datum to use
size_t.

Signed-off-by: Martin Kelly <mkelly@xxxxxxxx>
Cc: <Stable@xxxxxxxxxxxxxxx>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/iio/buffer/industrialio-buffer-dma.c |    2 +-
 drivers/iio/buffer/kfifo_buf.c               |    4 ++--
 include/linux/iio/buffer_impl.h              |    6 +++---
 3 files changed, 6 insertions(+), 6 deletions(-)

--- a/drivers/iio/buffer/industrialio-buffer-dma.c
+++ b/drivers/iio/buffer/industrialio-buffer-dma.c
@@ -587,7 +587,7 @@ EXPORT_SYMBOL_GPL(iio_dma_buffer_set_byt
  * Should be used as the set_length callback for iio_buffer_access_ops
  * struct for DMA buffers.
  */
-int iio_dma_buffer_set_length(struct iio_buffer *buffer, int length)
+int iio_dma_buffer_set_length(struct iio_buffer *buffer, unsigned int length)
 {
 	/* Avoid an invalid state */
 	if (length < 2)
--- a/drivers/iio/buffer/kfifo_buf.c
+++ b/drivers/iio/buffer/kfifo_buf.c
@@ -22,7 +22,7 @@ struct iio_kfifo {
 #define iio_to_kfifo(r) container_of(r, struct iio_kfifo, buffer)
 
 static inline int __iio_allocate_kfifo(struct iio_kfifo *buf,
-				int bytes_per_datum, int length)
+			size_t bytes_per_datum, unsigned int length)
 {
 	if ((length == 0) || (bytes_per_datum == 0))
 		return -EINVAL;
@@ -67,7 +67,7 @@ static int iio_set_bytes_per_datum_kfifo
 	return 0;
 }
 
-static int iio_set_length_kfifo(struct iio_buffer *r, int length)
+static int iio_set_length_kfifo(struct iio_buffer *r, unsigned int length)
 {
 	/* Avoid an invalid state */
 	if (length < 2)
--- a/include/linux/iio/buffer_impl.h
+++ b/include/linux/iio/buffer_impl.h
@@ -53,7 +53,7 @@ struct iio_buffer_access_funcs {
 	int (*request_update)(struct iio_buffer *buffer);
 
 	int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd);
-	int (*set_length)(struct iio_buffer *buffer, int length);
+	int (*set_length)(struct iio_buffer *buffer, unsigned int length);
 
 	int (*enable)(struct iio_buffer *buffer, struct iio_dev *indio_dev);
 	int (*disable)(struct iio_buffer *buffer, struct iio_dev *indio_dev);
@@ -72,10 +72,10 @@ struct iio_buffer_access_funcs {
  */
 struct iio_buffer {
 	/** @length: Number of datums in buffer. */
-	int length;
+	unsigned int length;
 
 	/**  @bytes_per_datum: Size of individual datum including timestamp. */
-	int bytes_per_datum;
+	size_t bytes_per_datum;
 
 	/**
 	 * @access: Buffer access functions associated with the