Re: [RFC PATCH v2 09/25] driver core: Add per-device pisa_* sysfs attributes for PISA optin

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential
issue to consider:
- [Low] iommu/pisa: missing CONFIG_SYSFS guard in test_dev_pisa_attrs()
--

commit 6fe77bab9a66f127e26564b7f0b1c45730cf6ab8
Author: Luigi Rizzo <lrizzo@google.com>

driver core: Add per-device pisa_* sysfs attributes for PISA optin

This commit adds per-device boolean sysfs attributes (pisa_coherent,
pisa_rx_bufs, pisa_tx_bufs, and pisa_tx_skb_heads) to struct device for
selective PISA opt-in, along with helper functions and a KUnit test.

> diff --git a/drivers/iommu/pisa-kunit.c b/drivers/iommu/pisa-kunit.c
> index e16268d55f3de..ab64657ad5c58 100644
> --- a/drivers/iommu/pisa-kunit.c
> +++ b/drivers/iommu/pisa-kunit.c
[ ... ]
> @@ -350,6 +352,70 @@ static void test_map_and_domain_lifecycle(struct kunit *test)
>  }
>  #endif /* CONFIG_IOMMU_DMA */
>  
> +static void kunit_check_pisa_attr(struct kunit *test, struct device *dev,
> +				  const char *name, bool *field)
> +{
> +	const struct sysfs_ops *ops = dev->kobj.ktype->sysfs_ops;
> +	struct kernfs_node *kn;
> +	char *buf;
> +
> +	buf = (char *)__get_free_page(GFP_KERNEL);
> +	KUNIT_EXPECT_NOT_NULL(test, buf);
> +	if (!buf)
> +		return;
> +	kn = kernfs_find_and_get(dev->kobj.sd, name);
> +	KUNIT_EXPECT_NOT_NULL(test, kn);

[Severity: Low]
Should test_dev_pisa_attrs() be guarded by CONFIG_SYSFS?

When CONFIG_SYSFS is disabled, device_register() leaves dev->kobj.sd as
NULL.  Passing NULL to kernfs_find_and_get() causes a NULL pointer
dereference in kernfs_root() when CONFIG_KERNFS=y, or fails the
KUNIT_EXPECT_NOT_NULL(test, kn) assertion when CONFIG_KERNFS=n.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261109182533.3594984-1-lrizzo@google.com?part=9