Re: [PATCH v3 4/4] of: unittest: cover /aliases updates from overlay apply/revert

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Holding a device node reference across `of_overlay_remove()` causes a memory leak and unexpected kernel error logs.
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--- Patch [4]: [PATCH v3 4/4] of: unittest: cover /aliases updates from overlay apply/revert ---
commit 4a0912943dbf2d4f5c928768a852d7834811ba59
Author: Abdurrahman Hussain <abdurrahman@nexthop.ai>

of: unittest: cover /aliases updates from overlay apply/revert

This commit adds an overlay test to ensure /aliases updates work correctly
across apply and revert when the overlay grafts a node with an alias.

> diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
> --- a/drivers/of/unittest.c
> +++ b/drivers/of/unittest.c

[ ... ]

> +static void __init of_unittest_overlay_alias(void)
> +{

[ ... ]

> +	/* hold a ref across the revert for the post-remove check */
> +	target = of_find_node_by_path(target_path);
> +	if (!target) {
> +		unittest(0, "could not find grafted target %s\n", target_path);
> +		goto out_remove;
> +	}
> +
> +	id = of_alias_get_id(target, "testcase-alias");
> +	unittest(id == 99,
> +		 "of_alias_get_id() = %d after overlay apply, expected 99\n",
> +		 id);
> +
> +out_remove:
> +	ret = of_overlay_remove(&ovcs_id);

[Severity: Medium]
Does holding this device node reference across of_overlay_remove() cause a
memory leak and unexpected kernel error logs?

When the reference to the target node is held, __of_changeset_entry_destroy()
observes a refcount greater than 1, which triggers an "ERROR: memory leak"
log and skips the OF_OVERLAY_FREE_CSET flag.

Subsequently, when of_node_put(target) drops the refcount down to 0,
of_node_release() logs another memory leak error and returns without freeing
the node memory.

> +	if (ret) {
> +		unittest(0, "overlay_alias remove failed, ret = %d\n", ret);
> +		of_node_put(target);
> +		goto out_put_base;
> +	}
> +
> +	if (target) {
> +		id = of_alias_get_id(target, "testcase-alias");
> +		unittest(id == -ENODEV,
> +			 "of_alias_get_id() = %d after overlay remove, expected -ENODEV\n",
> +			 id);
> +		of_node_put(target);
> +	}
> +
> +out_put_base:
> +	of_node_put(base);
> +}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260721-nh-of-alias-overlay-v3-0-7001028fe2f5@nexthop.ai?part=4