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iio: buffer: Make length attribute read only for buffers without set_length 

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@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This commit is contained in:
Lars-Peter Clausen 2014-11-26 18:55:16 +01:00 committed by Jonathan Cameron
parent 08e7e0adaa
commit 8d92db2827
1 changed files with 7 additions and 3 deletions
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10
drivers/iio/industrialio-buffer.c
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@ -418,8 +418,7 @@ 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);
@ -760,6 +759,8 @@ 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);
@ -786,7 +787,10 @@ int iio_buffer_alloc_sysfs_and_mask(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,