Re: [PATCH] rust: module_param: return value by copy from `value`

[Andreas Hindborg]

"Gary Guo" <gary@xxxxxxxxxxx> writes:

> On Fri May 29, 2026 at 9:41 AM BST, Andreas Hindborg wrote:
>> For `Copy` parameter types it is more ergonomic to retrieve the
>> parameter value by copy than through a shared reference. Change
>> `ModuleParamAccess::value` to return `T` by copy when `T: Copy`,
>> and rename the previous reference-returning accessor to
>> `value_ref`. Update the in-tree caller in `rust_minimal`.
>>
>> Suggested-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
>> Signed-off-by: Andreas Hindborg <a.hindborg@xxxxxxxxxx>
>> ---
>> This change was suggested during review of the rust null block series [1].
>>
>> [1] https://lore.kernel.org/r/abfe2LbhLzXiGCkA@xxxxxxxxxx
>> ---
>>  rust/kernel/module_param.rs  | 15 ++++++++++++++-
>>  samples/rust/rust_minimal.rs |  2 +-
>>  2 files changed, 15 insertions(+), 2 deletions(-)
>>
>> diff --git a/rust/kernel/module_param.rs b/rust/kernel/module_param.rs
>> index 6a8a7a875643..701210206bba 100644
>> --- a/rust/kernel/module_param.rs
>> +++ b/rust/kernel/module_param.rs
>> @@ -132,9 +132,12 @@ pub const fn new(default: T) -> Self {
>>      }
>>  
>>      /// Get a shared reference to the parameter value.
>> +    ///
>> +    /// Returns a reference to the value supplied at module load time, or a
>> +    /// reference to the default value if the parameter has not been set.
>>      // 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 +149,16 @@ pub const fn as_void_ptr(&self) -> *mut c_void {
>>      }
>>  }
>>  
>> +impl<T: Copy> ModuleParamAccess<T> {
>
> Instead of adding a new impl block, this should just be moved to immediately
> after (or before) `value_ref` with a `where T: Copy` bound instead.
>
> This makes related code close together for readers of the code.

Will do.


Best regards,
Andreas Hindborg