[PATCH 4.4] iio:buffer: make length types match kfifo types

[Ben Hutchings <ben.hutchings@xxxxxxxxxxxxxxx>]

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 4.4:
 - Drop change to iio_dma_buffer_set_length()
 - Adjust filename, context]
Signed-off-by: Ben Hutchings <ben.hutchings@xxxxxxxxxxxxxxx>
---
 drivers/iio/buffer/kfifo_buf.c | 4 ++--
 include/linux/iio/buffer.h     | 6 +++---
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/buffer/kfifo_buf.c b/drivers/iio/buffer/kfifo_buf.c
index 7ef9b13262a8..e44181f9eb36 100644
--- a/drivers/iio/buffer/kfifo_buf.c
+++ b/drivers/iio/buffer/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;
@@ -71,7 +71,7 @@ static int iio_set_bytes_per_datum_kfifo(struct iio_buffer *r, size_t bpd)
 	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)
diff --git a/include/linux/iio/buffer.h b/include/linux/iio/buffer.h
index 1600c55828e0..93a774ce4922 100644
--- a/include/linux/iio/buffer.h
+++ b/include/linux/iio/buffer.h
@@ -49,7 +49,7 @@ 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);
 
 	void (*release)(struct iio_buffer *buffer);
 
@@ -78,8 +78,8 @@ struct iio_buffer_access_funcs {
  * @watermark:		[INTERN] number of datums to wait for poll/read.
  */
 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;
-- 
Ben Hutchings, Software Developer                         Codethink Ltd
https://www.codethink.co.uk/                 Dale House, 35 Dale Street
                                     Manchester, M1 2HF, United Kingdom