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

[Ben Hutchings]

3.16.60-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Martin Kelly <mke...@xevo.com>

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 <mke...@xevo.com>
Signed-off-by: Jonathan Cameron <jonathan.came...@huawei.com>
[bwh: Backported to 3.16:
 - Drop change in iio_dma_buffer_set_length()
 - Adjust filenames, context]
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
--- 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;