[PATCH] rust: bitfield: always inline test conversions

[PATCH] rust: bitfield: always inline test conversions

[Miguel Ojeda]

From: Antoni Boucher <bouanto@zoho.com>

When using the Rust GCC backend (i.e. `rustc_codegen_gcc`), GCC does not
inline enough these `Bounded::from_expr` calls:

    /usr/bin/x86_64-linux-gnu-ld.bfd: rust/kernel.o: in function `<kernel::num::bounded::Bounded<u16, 2> as core::convert::From<kernel::bitfield::tests::Priority>>::from':
    fake.c:(.text.unlikely+0x7be): undefined reference to `rust_build_error'

    /usr/bin/x86_64-linux-gnu-ld.bfd: rust/kernel.o: in function `<kernel::num::bounded::Bounded<u64, 4> as core::convert::From<kernel::bitfield::tests::MemoryType>>::from':
    fake.c:(.text.unlikely+0x90d): undefined reference to `rust_build_error'

Thus, similar to commit bc197e24a3ac ("rust: num: bounded: Always inline
fits_within and from_expr"), mark them as `#[inline(always)]`.

Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Antoni Boucher <bouanto@zoho.com>
[ Reworded to add the error and to follow our usual style and sent on
  behalf of Antoni, who found this during his work to support Rust for
  Linux with the GCC backend, i.e. with `rustc_codegen_gcc`.- Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
 rust/kernel/bitfield.rs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/rust/kernel/bitfield.rs b/rust/kernel/bitfield.rs
index 35ede53f2b8e..a0d089423f21 100644
--- a/rust/kernel/bitfield.rs
+++ b/rust/kernel/bitfield.rs
@@ -581,6 +581,7 @@ fn try_from(value: Bounded<u64, 4>) -> Result<Self, Self::Error> {
     }
 
     impl From<MemoryType> for Bounded<u64, 4> {
+        #[inline(always)]
         fn from(mt: MemoryType) -> Bounded<u64, 4> {
             Bounded::from_expr(mt as u64)
         }
@@ -606,6 +607,7 @@ fn from(value: Bounded<u16, 2>) -> Self {
     }
 
     impl From<Priority> for Bounded<u16, 2> {
+        #[inline(always)]
         fn from(p: Priority) -> Bounded<u16, 2> {
             Bounded::from_expr(p as u16)
         }

base-commit: dc01dfb37b34beeefcfe1c3055364d41a4070c7e
-- 
2.55.0

Re: [PATCH] rust: bitfield: always inline test conversions

[Danilo Krummrich]

On Fri Aug 7, 2026 at 7:50 PM CEST, Miguel Ojeda wrote:
> From: Antoni Boucher <bouanto@zoho.com>
>
> When using the Rust GCC backend (i.e. `rustc_codegen_gcc`), GCC does not
> inline enough these `Bounded::from_expr` calls:
>
>     /usr/bin/x86_64-linux-gnu-ld.bfd: rust/kernel.o: in function `<kernel::num::bounded::Bounded<u16, 2> as core::convert::From<kernel::bitfield::tests::Priority>>::from':
>     fake.c:(.text.unlikely+0x7be): undefined reference to `rust_build_error'
>
>     /usr/bin/x86_64-linux-gnu-ld.bfd: rust/kernel.o: in function `<kernel::num::bounded::Bounded<u64, 4> as core::convert::From<kernel::bitfield::tests::MemoryType>>::from':
>     fake.c:(.text.unlikely+0x90d): undefined reference to `rust_build_error'
>
> Thus, similar to commit bc197e24a3ac ("rust: num: bounded: Always inline
> fits_within and from_expr"), mark them as `#[inline(always)]`.
>
> Assisted-by: Claude:claude-opus-4-8
> Signed-off-by: Antoni Boucher <bouanto@zoho.com>
> [ Reworded to add the error and to follow our usual style and sent on
>   behalf of Antoni, who found this during his work to support Rust for
>   Linux with the GCC backend, i.e. with `rustc_codegen_gcc`.- Miguel ]
> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Reviewed-by: Danilo Krummrich <dakr@kernel.org>

Re: [PATCH] rust: bitfield: always inline test conversions

[Gary Guo]

On Fri Aug 7, 2026 at 6:50 PM BST, Miguel Ojeda wrote:
> From: Antoni Boucher <bouanto@zoho.com>
> 
> When using the Rust GCC backend (i.e. `rustc_codegen_gcc`), GCC does not
> inline enough these `Bounded::from_expr` calls:
> 
>     /usr/bin/x86_64-linux-gnu-ld.bfd: rust/kernel.o: in function `<kernel::num::bounded::Bounded<u16, 2> as core::convert::From<kernel::bitfield::tests::Priority>>::from':
>     fake.c:(.text.unlikely+0x7be): undefined reference to `rust_build_error'
> 
>     /usr/bin/x86_64-linux-gnu-ld.bfd: rust/kernel.o: in function `<kernel::num::bounded::Bounded<u64, 4> as core::convert::From<kernel::bitfield::tests::MemoryType>>::from':
>     fake.c:(.text.unlikely+0x90d): undefined reference to `rust_build_error'
> 
> Thus, similar to commit bc197e24a3ac ("rust: num: bounded: Always inline
> fits_within and from_expr"), mark them as `#[inline(always)]`.
> 
> Assisted-by: Claude:claude-opus-4-8
> Signed-off-by: Antoni Boucher <bouanto@zoho.com>
> [ Reworded to add the error and to follow our usual style and sent on
>   behalf of Antoni, who found this during his work to support Rust for
>   Linux with the GCC backend, i.e. with `rustc_codegen_gcc`.- Miguel ]
> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Reviewed-by: Gary Guo <gary@garyguo.net>

> ---
>  rust/kernel/bitfield.rs | 2 ++
>  1 file changed, 2 insertions(+)

Re: [PATCH] rust: bitfield: always inline test conversions

[Alexandre Courbot]

On Sat Aug 8, 2026 at 2:50 AM JST, Miguel Ojeda wrote:
> From: Antoni Boucher <bouanto@zoho.com>
>
> When using the Rust GCC backend (i.e. `rustc_codegen_gcc`), GCC does not
> inline enough these `Bounded::from_expr` calls:
>
>     /usr/bin/x86_64-linux-gnu-ld.bfd: rust/kernel.o: in function `<kernel::num::bounded::Bounded<u16, 2> as core::convert::From<kernel::bitfield::tests::Priority>>::from':
>     fake.c:(.text.unlikely+0x7be): undefined reference to `rust_build_error'
>
>     /usr/bin/x86_64-linux-gnu-ld.bfd: rust/kernel.o: in function `<kernel::num::bounded::Bounded<u64, 4> as core::convert::From<kernel::bitfield::tests::MemoryType>>::from':
>     fake.c:(.text.unlikely+0x90d): undefined reference to `rust_build_error'
>
> Thus, similar to commit bc197e24a3ac ("rust: num: bounded: Always inline
> fits_within and from_expr"), mark them as `#[inline(always)]`.
>
> Assisted-by: Claude:claude-opus-4-8
> Signed-off-by: Antoni Boucher <bouanto@zoho.com>
> [ Reworded to add the error and to follow our usual style and sent on
>   behalf of Antoni, who found this during his work to support Rust for
>   Linux with the GCC backend, i.e. with `rustc_codegen_gcc`.- Miguel ]
> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

There always are a couple of these going through the cracks, aren't
there. :)

Acked-by: Alexandre Courbot <acourbot@nvidia.com>

Re: [PATCH] rust: bitfield: always inline test conversions

[Miguel Ojeda]

On Fri, Aug 7, 2026 at 7:50 PM Miguel Ojeda <ojeda@kernel.org> wrote:
>
> From: Antoni Boucher <bouanto@zoho.com>
>
> When using the Rust GCC backend (i.e. `rustc_codegen_gcc`), GCC does not
> inline enough these `Bounded::from_expr` calls:
>
>     /usr/bin/x86_64-linux-gnu-ld.bfd: rust/kernel.o: in function `<kernel::num::bounded::Bounded<u16, 2> as core::convert::From<kernel::bitfield::tests::Priority>>::from':
>     fake.c:(.text.unlikely+0x7be): undefined reference to `rust_build_error'
>
>     /usr/bin/x86_64-linux-gnu-ld.bfd: rust/kernel.o: in function `<kernel::num::bounded::Bounded<u64, 4> as core::convert::From<kernel::bitfield::tests::MemoryType>>::from':
>     fake.c:(.text.unlikely+0x90d): undefined reference to `rust_build_error'
>
> Thus, similar to commit bc197e24a3ac ("rust: num: bounded: Always inline
> fits_within and from_expr"), mark them as `#[inline(always)]`.
>
> Assisted-by: Claude:claude-opus-4-8
> Signed-off-by: Antoni Boucher <bouanto@zoho.com>
> [ Reworded to add the error and to follow our usual style and sent on
>   behalf of Antoni, who found this during his work to support Rust for
>   Linux with the GCC backend, i.e. with `rustc_codegen_gcc`.- Miguel ]
> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Applied to `rust-next` -- thanks everyone!

Cheers,
Miguel