On Mon Mar 23, 2026 at 12:47 PM GMT, Andreas Hindborg wrote:
> Rename the existing `value()` method to `value_ref()` which returns a
> shared reference to the parameter value, and add a new `value()`
> method on `ModuleParamAccess<T>` where `T: Copy` that returns the
> value by copy.
>
> This provides a more ergonomic API for the common case where the
> parameter type implements `Copy`, avoiding the need to explicitly
> dereference the return value at call sites.
>
> Currently `value_ref()` has no in-tree callers, but it will be needed
> when support for non-`Copy` parameter types such as arrays and
> strings is added.
>
> Signed-off-by: Andreas Hindborg <[email protected]>
> ---
> This change was suggested at [1].
>
> Link:
> https://lore.kernel.org/r/[email protected] [1]
> ---
> rust/kernel/module_param.rs | 11 ++++++++++-
> samples/rust/rust_minimal.rs | 2 +-
> 2 files changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/rust/kernel/module_param.rs b/rust/kernel/module_param.rs
> index 6a8a7a875643..5dcfe2ba87a1 100644
> --- a/rust/kernel/module_param.rs
> +++ b/rust/kernel/module_param.rs
> @@ -134,7 +134,7 @@ pub const fn new(default: T) -> Self {
> /// Get a shared reference to the parameter value.
> // Note: When sysfs access to parameters are enabled, we have to pass in
> a
> // held lock guard here.
> - pub fn value(&self) -> &T {
> + pub fn value_ref(&self) -> &T {
> self.value.as_ref().unwrap_or(&self.default)
> }
>
> @@ -146,6 +146,15 @@ pub const fn as_void_ptr(&self) -> *mut c_void {
> }
> }
>
> +impl<T: Copy> ModuleParamAccess<T> {
> + /// Get a copy of the parameter value.
> + // Note: When sysfs access to parameters are enabled, we have to pass in
> a
> + // held lock guard here.
> + pub fn value(&self) -> T {
It's better to keep this close to `value_ref` in the same impl block. The `T:
Copy` bound doesn't need to be on the impl block, it can be on the item itself
with
pub fn value(&self) -> T where T: Copy
Best,
Gary
> + self.value.copy().unwrap_or(self.default)
> + }
> +}
> +
> #[doc(hidden)]
> /// Generate a static
> [`kernel_param_ops`](srctree/include/linux/moduleparam.h) struct.
> ///
> diff --git a/samples/rust/rust_minimal.rs b/samples/rust/rust_minimal.rs
> index 8eb9583571d7..60d03df6cd80 100644
> --- a/samples/rust/rust_minimal.rs
> +++ b/samples/rust/rust_minimal.rs
> @@ -28,7 +28,7 @@ fn init(_module: &'static ThisModule) -> Result<Self> {
> pr_info!("Am I built-in? {}\n", !cfg!(MODULE));
> pr_info!(
> "test_parameter: {}\n",
> - *module_parameters::test_parameter.value()
> + module_parameters::test_parameter.value()
> );
>
> let mut numbers = KVec::new();
>
> ---
> base-commit: c369299895a591d96745d6492d4888259b004a9e
> change-id: 20260323-module-value-ref-5884b5ae6b2a
>
> Best regards,
