Re: [PATCH 15/79] block: rnull: add `use_per_node_hctx` config option

[Alice Ryhl]

On Mon, Feb 16, 2026 at 12:35:02AM +0100, Andreas Hindborg wrote:
> Add a configfs attribute to enable per-NUMA-node hardware contexts.
> When enabled, the driver creates one hardware queue per NUMA node
> instead of the default configuration.
> 
> Signed-off-by: Andreas Hindborg <a.hindborg@xxxxxxxxxx>

This and other patches make me think that module parameters should have
value() return a copy of the value (and require Copy). For non-copy
types, there can be a separate value_ref() method. You would avoid *so*
many asterisks by doing that.

> +configfs_attribute!(DeviceConfig, 8,
> +    show: |this, page| show_field(
> +        this.data.lock().submit_queues == kernel::num_online_nodes(), page
> +    ),
> +    store: |this, page| store_with_power_check(this, page, |this, page| {
> +        let value = core::str::from_utf8(page)?
> +            .trim()
> +            .parse::<u8>()
> +            .map_err(|_| kernel::error::code::EINVAL)?
> +            != 0;
> +
> +        if value {
> +            this.data.lock().submit_queues *= kernel::num_online_nodes();
> +        }

kstrtobool again. Also, this is *multiplying* the existing submit_queues
value by the number of NUMA nodes?

> +        use_per_node_hctx: u8 {
> +            default: 0,
> +            description:
> +        "Use per-node allocation for hardware context queues, 0-false, 1-true. Default: 0-false",
> +        },

formatting (rustfmt ignores macros)

Alice