Re: [PATCH 22/79] block: rnull: add no_sched module parameter and configfs attribute

[Alice Ryhl]

On Mon, Feb 16, 2026 at 12:35:09AM +0100, Andreas Hindborg wrote:
> Add support for disabling the default IO scheduler by adding:
> - no_sched module parameter to control scheduler selection at device
>   creation.
> - no_sched configfs attribute (ID 11) for runtime configuration.
> - Use of NO_DEFAULT_SCHEDULER flag when no_sched is enabled.
> 
> This allows bypassing the default 'mq-deadline' scheduler and using 'none'
> instead, which can improve performance for certain workloads. The flag
> selection logic is updated to use compound assignment operators for better
> readability.
> 
> Signed-off-by: Andreas Hindborg <a.hindborg@xxxxxxxxxx>

> +#[vtable]
> +impl configfs::AttributeOperations<11> for DeviceConfig {
> +    type Data = DeviceConfig;
> +
> +    fn show(this: &DeviceConfig, page: &mut [u8; PAGE_SIZE]) -> Result<usize> {
> +        let mut writer = kernel::str::Formatter::new(page);
> +
> +        if this.data.lock().no_sched {
> +            writer.write_str("1\n")?;
> +        } else {
> +            writer.write_str("0\n")?;
> +        }
> +
> +        Ok(writer.bytes_written())
> +    }
> +
> +    fn store(this: &DeviceConfig, page: &[u8]) -> Result {
> +        if this.data.lock().powered {
> +            return Err(EBUSY);
> +        }
> +
> +        this.data.lock().no_sched = kstrtobool_bytes(page)?;
> +
> +        Ok(())
> +    }

Not using your fancy macro. Also, TOCTOU.

Alice