Re: [PATCH v3 02/10] iio: backend: add devm_iio_backend_get_optional()

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] iio: backend: wrong fwnode used in __devm_iio_backend_fwnode_get()
--

commit ed5c232ab5f93ed7cb07750eadfee12a6f8577f8
Author: Rodrigo Alencar <rodrigo.alencar@analog.com>

iio: backend: add devm_iio_backend_get_optional()

This commit introduces devm_iio_backend_get_optional() to return NULL when
an IIO backend is not described in firmware. It also updates
__devm_iio_backend_fwnode_get() and __devm_iio_backend_fwnode_get_by_index()
so that missing io-backends or io-backend-names entries consistently return
-ENOENT without logging an error.

> diff --git a/drivers/iio/industrialio-backend.c b/drivers/iio/industrialio-backend.c
> index fbf5c39d76551..d12d163f45cad 100644
> --- a/drivers/iio/industrialio-backend.c
> +++ b/drivers/iio/industrialio-backend.c

[ ... ]

> @@ -1034,7 +1037,17 @@ static struct iio_backend *__devm_iio_backend_fwnode_get(struct device *dev, con
>  	int ret;
>  
>  	if (name) {
> +		if (!device_property_present(dev, "io-backend-names"))
> +			return ERR_PTR(-ENOENT);
> +
>  		ret = device_property_match_string(dev, "io-backend-names", name);

[Severity: Medium]
Should this check fwnode_property_present(fwnode, "io-backend-names")
(and fwnode_property_match_string(fwnode, "io-backend-names", name))
instead of querying dev?

__devm_iio_backend_fwnode_get() is also called by
devm_iio_backend_fwnode_get(), where a caller passes an explicit consumer
fwnode distinct from dev_fwnode(dev) (such as a child channel node):

devm_iio_backend_fwnode_get(dev, name, fwnode)
  __devm_iio_backend_fwnode_get(dev, name, fwnode)
    __devm_iio_backend_fwnode_get_by_index(dev, fwnode, index)
      fwnode_find_reference(fwnode, "io-backends", index)

When name is non-NULL and fwnode != dev_fwnode(dev), checking
device_property_present(dev, "io-backend-names") looks for the property on
dev rather than on fwnode, causing the lookup to fail with -ENOENT when
io-backend-names lives on the child fwnode or resolving the index from the
wrong node.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261103-ad9910-backend-support-v3-0-0e9224ddf7b7@analog.com?part=2