Re: [PATCH] i2c: rust: mark I2cAdapter methods as inline

[Onur Özkan]

On Thu, 21 May 2026 16:08:50 -0300
Nicolás Antinori <nico.antinori.7@xxxxxxxxx> wrote:

> When building the kernel using llvm-19.1.7-rust-1.85.0-x86_64, the
> following symbols are generated:
> 
> $ nm vmlinux | grep ' _R'.*I2cAdapter | rustfilt
> ffffffff817ff380 T <kernel::i2c::I2cAdapter>::get
> ffffffff817ff400 T <kernel::i2c::I2cAdapter as kernel::sync::aref::AlwaysRefCounted>::dec_ref
> ffffffff817ff3e0 T <kernel::i2c::I2cAdapter as kernel::sync::aref::AlwaysRefCounted>::inc_ref
> 
> However, these Rust symbols are trivial wrappers around the
> `i2c_get_adapter` and `i2c_put_adapter` functions. It doesn't make sense
> to go through a trivial wrapper for these functions.
> 
> Link: https://github.com/Rust-for-Linux/linux/issues/1145
> Suggested-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
> Signed-off-by: Nicolás Antinori <nico.antinori.7@xxxxxxxxx>

Thanks!

Reviewed-by: Onur Özkan <work@xxxxxxxxxxxxx>

> ---
>  rust/kernel/i2c.rs | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/rust/kernel/i2c.rs b/rust/kernel/i2c.rs
> index 7b908f0c5a58..07f9fd53c4e5 100644
> --- a/rust/kernel/i2c.rs
> +++ b/rust/kernel/i2c.rs
> @@ -397,6 +397,7 @@ pub fn index(&self) -> i32 {
>      }
>  
>      /// Gets pointer to an `i2c_adapter` by index.
> +    #[inline]
>      pub fn get(index: i32) -> Result<ARef<Self>> {
>          // SAFETY: `index` must refer to a valid I2C adapter; the kernel
>          // guarantees that `i2c_get_adapter(index)` returns either a valid
> @@ -416,11 +417,13 @@ pub fn get(index: i32) -> Result<ARef<Self>> {
>  
>  // SAFETY: Instances of `I2cAdapter` are always reference-counted.
>  unsafe impl AlwaysRefCounted for I2cAdapter {
> +    #[inline]
>      fn inc_ref(&self) {
>          // SAFETY: The existence of a shared reference guarantees that the refcount is non-zero.
>          unsafe { bindings::i2c_get_adapter(self.index()) };
>      }
>  
> +    #[inline]
>      unsafe fn dec_ref(obj: NonNull<Self>) {
>          // SAFETY: The safety requirements guarantee that the refcount is non-zero.
>          unsafe { bindings::i2c_put_adapter(obj.as_ref().as_raw()) }
> -- 
> 2.53.0
>