[PATCH v1 1/8] iio: core: Add opaque_struct_size() helper and use it

Andy Shevchenko
2023-07-20T20:53:41Z

Introduce opaque_struct_size() helper, which may be moved
to overflow.h in the future, and use it in the IIO core.

Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
drivers/iio/industrialio-core.c | 32 ++++++++++++++++++++++++--------
1 file changed, 24 insertions(+), 8 deletions(-)

diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index c117f50d0cf3..6cca86fd0ef9 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -1617,6 +1617,28 @@ const struct device_type iio_device_type = {
.release = iio_dev_release,
};

+/**
+ * opaque_struct_size() - Calculate size of opaque structure with trailing aligned data.
+ * @p: Pointer to the opaque structure.
+ * @a: Alignment in bytes before trailing data.
+ * @s: Data size in bytes (can be 0).
+ *
+ * Calculates size of memory needed for structure of @p followed by the aligned data
+ * of size @s. When @s is 0, the alignment @a is not taken into account and the result
+ * is an equivalent to sizeof(*(@p)).
+ *
+ * Returns: Number of bytes needed or SIZE_MAX on overflow.
+ */
+#define opaque_struct_size(p, a, s) ({ \
+ size_t _psize = sizeof(*(p)); \
+ size_t _asize = ALIGN(_psize, (a)); \
+ size_t _ssize = s; \
+ _ssize ? size_add(_asize, _ssize) : _psize; \
+})
+
+#define opaque_struct_data(p, a) \
+ ((void *)(p) + ALIGN(sizeof(*(p)), (a)))
+
/**
* iio_device_alloc() - allocate an iio_dev from a driver
* @parent: Parent device.
@@ -1628,19 +1650,13 @@ struct iio_dev *iio_device_alloc(struct device *parent, int sizeof_priv)
struct iio_dev *indio_dev;
size_t alloc_size;

- alloc_size = sizeof(struct iio_dev_opaque);
- if (sizeof_priv) {
- alloc_size = ALIGN(alloc_size, IIO_DMA_MINALIGN);
- alloc_size += sizeof_priv;
- }
-
+ alloc_size = opaque_struct_size(iio_dev_opaque, IIO_DMA_MINALIGN, sizeof_priv);
iio_dev_opaque = kzalloc(alloc_size, GFP_KERNEL);
if (!iio_dev_opaque)
return NULL;

indio_dev = &iio_dev_opaque->indio_dev;
- indio_dev->priv = (char *)iio_dev_opaque +
- ALIGN(sizeof(struct iio_dev_opaque), IIO_DMA_MINALIGN);
+ indio_dev->priv = opaque_struct_data(iio_dev_opaque, IIO_DMA_MINALIGN);

indio_dev->dev.parent = parent;
indio_dev->dev.type = &iio_device_type;
--
2.40.0.1.gaa8946217a0b