[PATCH] rust: Mark all from() for Error functions inline

[PATCH] rust: Mark all from() for Error functions inline

[alistair23]

From: Alistair Francis <alistair.francis@wdc.com>

Mark all of the existing

impl From<...> for Error {
    fn from(err: ...) -> Self {
        ...
    }
}

functions as `#[inline]`

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
---
 rust/kernel/alloc/kvec/errors.rs        | 3 +++
 rust/kernel/error.rs                    | 6 ++++++
 rust/kernel/ptr/projection.rs           | 2 +-
 rust/kernel/xarray.rs                   | 1 +
 rust/pin-init/examples/error.rs         | 2 ++
 rust/pin-init/examples/pthread_mutex.rs | 2 ++
 rust/syn/error.rs                       | 1 +
 7 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/rust/kernel/alloc/kvec/errors.rs b/rust/kernel/alloc/kvec/errors.rs
index e7de5049ee47..985c5f2c3962 100644
--- a/rust/kernel/alloc/kvec/errors.rs
+++ b/rust/kernel/alloc/kvec/errors.rs
@@ -15,6 +15,7 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 }
 
 impl<T> From<PushError<T>> for Error {
+    #[inline]
     fn from(_: PushError<T>) -> Error {
         // Returning ENOMEM isn't appropriate because the system is not out of memory. The vector
         // is just full and we are refusing to resize it.
@@ -32,6 +33,7 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 }
 
 impl From<RemoveError> for Error {
+    #[inline]
     fn from(_: RemoveError) -> Error {
         EINVAL
     }
@@ -55,6 +57,7 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 }
 
 impl<T> From<InsertError<T>> for Error {
+    #[inline]
     fn from(_: InsertError<T>) -> Error {
         EINVAL
     }
diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs
index 258b12afdcba..935787c2a91c 100644
--- a/rust/kernel/error.rs
+++ b/rust/kernel/error.rs
@@ -216,36 +216,42 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 }
 
 impl From<AllocError> for Error {
+    #[inline]
     fn from(_: AllocError) -> Error {
         code::ENOMEM
     }
 }
 
 impl From<TryFromIntError> for Error {
+    #[inline]
     fn from(_: TryFromIntError) -> Error {
         code::EINVAL
     }
 }
 
 impl From<Utf8Error> for Error {
+    #[inline]
     fn from(_: Utf8Error) -> Error {
         code::EINVAL
     }
 }
 
 impl From<LayoutError> for Error {
+    #[inline]
     fn from(_: LayoutError) -> Error {
         code::ENOMEM
     }
 }
 
 impl From<fmt::Error> for Error {
+    #[inline]
     fn from(_: fmt::Error) -> Error {
         code::EINVAL
     }
 }
 
 impl From<core::convert::Infallible> for Error {
+    #[inline]
     fn from(e: core::convert::Infallible) -> Error {
         match e {}
     }
diff --git a/rust/kernel/ptr/projection.rs b/rust/kernel/ptr/projection.rs
index 140ea8e21617..7e37390da6c6 100644
--- a/rust/kernel/ptr/projection.rs
+++ b/rust/kernel/ptr/projection.rs
@@ -13,7 +13,7 @@
 pub struct OutOfBound;
 
 impl From<OutOfBound> for Error {
-    #[inline(always)]
+    #[inline]
     fn from(_: OutOfBound) -> Self {
         ERANGE
     }
diff --git a/rust/kernel/xarray.rs b/rust/kernel/xarray.rs
index a49d6db28845..46e5f43223fe 100644
--- a/rust/kernel/xarray.rs
+++ b/rust/kernel/xarray.rs
@@ -172,6 +172,7 @@ pub struct StoreError<T> {
 }
 
 impl<T> From<StoreError<T>> for Error {
+    #[inline]
     fn from(value: StoreError<T>) -> Self {
         value.error
     }
diff --git a/rust/pin-init/examples/error.rs b/rust/pin-init/examples/error.rs
index 8f4e135eb8ba..96f095398e8d 100644
--- a/rust/pin-init/examples/error.rs
+++ b/rust/pin-init/examples/error.rs
@@ -11,6 +11,7 @@
 pub struct Error;
 
 impl From<Infallible> for Error {
+    #[inline]
     fn from(e: Infallible) -> Self {
         match e {}
     }
@@ -18,6 +19,7 @@ fn from(e: Infallible) -> Self {
 
 #[cfg(feature = "alloc")]
 impl From<AllocError> for Error {
+    #[inline]
     fn from(_: AllocError) -> Self {
         Self
     }
diff --git a/rust/pin-init/examples/pthread_mutex.rs b/rust/pin-init/examples/pthread_mutex.rs
index 4e082ec7d5de..aae3492d3958 100644
--- a/rust/pin-init/examples/pthread_mutex.rs
+++ b/rust/pin-init/examples/pthread_mutex.rs
@@ -49,6 +49,7 @@ pub enum Error {
     }
 
     impl From<Infallible> for Error {
+        #[inline]
         fn from(e: Infallible) -> Self {
             match e {}
         }
@@ -56,6 +57,7 @@ fn from(e: Infallible) -> Self {
 
     #[cfg(feature = "alloc")]
     impl From<AllocError> for Error {
+        #[inline]
         fn from(_: AllocError) -> Self {
             Self::Alloc
         }
diff --git a/rust/syn/error.rs b/rust/syn/error.rs
index 6fa0faf7f4e4..636f07d56d05 100644
--- a/rust/syn/error.rs
+++ b/rust/syn/error.rs
@@ -405,6 +405,7 @@ impl Copy for SpanRange {}
 impl std::error::Error for Error {}
 
 impl From<LexError> for Error {
+    #[inline]
     fn from(err: LexError) -> Self {
         Error::new(err.span(), err)
     }
-- 
2.53.0

Re: [PATCH] rust: Mark all from() for Error functions inline

[Miguel Ojeda]

On Fri, Mar 20, 2026 at 2:19 AM <alistair23@gmail.com> wrote:
>
>  rust/kernel/alloc/kvec/errors.rs        | 3 +++
>  rust/kernel/error.rs                    | 6 ++++++
>  rust/kernel/ptr/projection.rs           | 2 +-
>  rust/kernel/xarray.rs                   | 1 +
>  rust/pin-init/examples/error.rs         | 2 ++
>  rust/pin-init/examples/pthread_mutex.rs | 2 ++
>  rust/syn/error.rs                       | 1 +

Please Cc all the relevant maintainers and reviewers using e.g.
`scripts/get_maintainer.pl`.

The commit log also should explain why we mark them as such. It also
doesn't say that one `inline(always)` was lowered to `inline` as well
and why that would be preferred (or not).

Thanks!

Cheers,
Miguel

Re: [PATCH] rust: Mark all from() for Error functions inline

[Benno Lossin]

On Fri Mar 20, 2026 at 2:18 AM CET, alistair23 wrote:
> From: Alistair Francis <alistair.francis@wdc.com>
>
> Mark all of the existing
>
> impl From<...> for Error {
>     fn from(err: ...) -> Self {
>         ...
>     }
> }
>
> functions as `#[inline]`
>
> Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
> ---
>  rust/kernel/alloc/kvec/errors.rs        | 3 +++
>  rust/kernel/error.rs                    | 6 ++++++
>  rust/kernel/ptr/projection.rs           | 2 +-
>  rust/kernel/xarray.rs                   | 1 +
>  rust/pin-init/examples/error.rs         | 2 ++
>  rust/pin-init/examples/pthread_mutex.rs | 2 ++

Please split the pin-init changes into a separate patch.

Also note that I prefer to take patches to pin-init upstream:

    https://github.com/rust-for-linux/pin-init

I'm also open to picking it from the mailing list if you don't want to
go to GitHub.

Cheers,
Benno

>  rust/syn/error.rs                       | 1 +
>  7 files changed, 16 insertions(+), 1 deletion(-)