[PATCH 3.16 074/366] iio:buffer: make length types match kfifo types

[Ben Hutchings <ben@xxxxxxxxxxxxxxx>]

3.16.60-rc1 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>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
[bwh: Backported to 3.16:
 - Drop change in iio_dma_buffer_set_length()
 - Adjust filenames, context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/drivers/iio/kfifo_buf.c
+++ b/drivers/iio/kfifo_buf.c
@@ -19,7 +19,7 @@ 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;
@@ -87,7 +87,7 @@ 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.h
+++ b/include/linux/iio/buffer.h
@@ -52,7 +52,7 @@ struct iio_buffer_access_funcs {
 	int (*get_bytes_per_datum)(struct iio_buffer *buffer);
 	int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd);
 	int (*get_length)(struct iio_buffer *buffer);
-	int (*set_length)(struct iio_buffer *buffer, int length);
+	int (*set_length)(struct iio_buffer *buffer, unsigned int length);
 
 	void (*release)(struct iio_buffer *buffer);
 };
@@ -78,8 +78,8 @@ struct iio_buffer_access_funcs {
  * @ref:		[INTERN] reference count of the buffer.
  */
 struct iio_buffer {
-	int					length;
-	int					bytes_per_datum;
+	unsigned int				length;
+	size_t					bytes_per_datum;
 	struct attribute_group			*scan_el_attrs;
 	long					*scan_mask;
 	bool					scan_timestamp;