Re: [PATCH v3 3/4] kallsyms: Add dynamic lookup index for batch resolution

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] kallsyms: missing __rcu annotation on dyn_kallsyms_offsets
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commit 6904f1dc3af3434d5089338b55024b752738c7d3
Author: Jim Cromie <jim.cromie@gmail.com>

kallsyms: Add dynamic lookup index for batch resolution

This patch introduces a dynamic u32 lookup index in transient RAM to
accelerate batch symbol resolution during high-volume workloads. It adds
start and end routines to manage the lifetime of the lookup index and
updates the symbol offset lookup to utilize it when available.

> diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
> index d18d78e626db2..06c79ad70cfdc 100644
> --- a/kernel/kallsyms.c
> +++ b/kernel/kallsyms.c
[ ... ]
> +/*
> + * Dynamic symbol offset table.
> + * Allocated on demand during high-volume lookup batches and reclaimed after.
> + */
> +static u32 *dyn_kallsyms_offsets __read_mostly;

[Severity: Low]
Does this declaration need an __rcu annotation?

The pointer is later updated and read using RCU primitives like
rcu_assign_pointer() and rcu_dereference(). Adding __rcu would enable
sparse type checking and prevent static analysis warnings.

[ ... ]
> +void kallsyms_lookup_batch_end(void)
> +{
> +	u32 *offsets = NULL;
> +
> +	mutex_lock(&dyn_kallsyms_mutex);
> +	if (WARN_ON(!dyn_kallsyms_refcnt))
> +		goto out;
> +
> +	if (--dyn_kallsyms_refcnt == 0) {
> +		offsets = dyn_kallsyms_offsets;

[Severity: Low]
Once the __rcu annotation is added to the declaration, will this bare read
trigger sparse warnings?

Since this read is performed under the dyn_kallsyms_mutex, should it use
rcu_dereference_protected() or rcu_access_pointer() instead to satisfy type
safety and static analysis checks?

> +		rcu_assign_pointer(dyn_kallsyms_offsets, NULL);
> +	}
> +out:
> +	mutex_unlock(&dyn_kallsyms_mutex);

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Sashiko AI review · https://sashiko.dev/#/patchset/20260922-ksyms-tune-v3-0-681a34ea05d9@gmail.com?part=3