On 26/11/14 17:55, Lars-Peter Clausen wrote:
> If a buffer implementation does not implement the set_length() callback the
> length will be static and can not be changed by userspace. Mark the length
> attribute as a read only property in this case so userspace is aware of this
> rather than just silently accepting any length value.
>
> Signed-off-by: Lars-Peter Clausen <lars@xxxxxxxxxx>
Nice little change.
Thanks
Jonathan
> ---
> drivers/iio/industrialio-buffer.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
> index a4d3ff6..3e0c3a9 100644
> --- a/drivers/iio/industrialio-buffer.c
> +++ b/drivers/iio/industrialio-buffer.c
> @@ -416,8 +416,7 @@ static ssize_t iio_buffer_write_length(struct device *dev,
> if (iio_buffer_is_active(indio_dev->buffer)) {
> ret = -EBUSY;
> } else {
> - if (buffer->access->set_length)
> - buffer->access->set_length(buffer, val);
> + buffer->access->set_length(buffer, val);
> ret = 0;
> }
> mutex_unlock(&indio_dev->mlock);
> @@ -755,6 +754,8 @@ static const char * const iio_scan_elements_group_name = "scan_elements";
>
> static DEVICE_ATTR(length, S_IRUGO | S_IWUSR, iio_buffer_read_length,
> iio_buffer_write_length);
> +static struct device_attribute dev_attr_length_ro = __ATTR(length,
> + S_IRUGO, iio_buffer_read_length, NULL);
> static DEVICE_ATTR(enable, S_IRUGO | S_IWUSR,
> iio_buffer_show_enable, iio_buffer_store_enable);
>
> @@ -781,7 +782,10 @@ int iio_buffer_alloc_sysfs(struct iio_dev *indio_dev)
> if (!buffer->buffer_group.attrs)
> return -ENOMEM;
>
> - buffer->buffer_group.attrs[0] = &dev_attr_length.attr;
> + if (buffer->access->set_length)
> + buffer->buffer_group.attrs[0] = &dev_attr_length.attr;
> + else
> + buffer->buffer_group.attrs[0] = &dev_attr_length_ro.attr;
> buffer->buffer_group.attrs[1] = &dev_attr_enable.attr;
> if (buffer->attrs)
> memcpy(&buffer->buffer_group.attrs[2], buffer->attrs,
>
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