linux-kernel - Re: [PATCH v2 07/10] rust: add `io::Io` base type

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Message-ID: <87zfr9guer.fsf@metaspace.dk>
Date: Tue, 25 Jun 2024 12:59:24 +0200
From: Andreas Hindborg <nmi@...aspace.dk>
To: Danilo Krummrich <dakr@...hat.com>
Cc: gregkh@...uxfoundation.org,  rafael@...nel.org,  bhelgaas@...gle.com,
  ojeda@...nel.org,  alex.gaynor@...il.com,  wedsonaf@...il.com,
  boqun.feng@...il.com,  gary@...yguo.net,  bjorn3_gh@...tonmail.com,
  benno.lossin@...ton.me,  a.hindborg@...sung.com,  aliceryhl@...gle.com,
  airlied@...il.com,  fujita.tomonori@...il.com,  lina@...hilina.net,
  pstanner@...hat.com,  ajanulgu@...hat.com,  lyude@...hat.com,
  robh@...nel.org,  daniel.almeida@...labora.com,
  rust-for-linux@...r.kernel.org,  linux-kernel@...r.kernel.org,
  linux-pci@...r.kernel.org
Subject: Re: [PATCH v2 07/10] rust: add `io::Io` base type

Hi Danilo,

Danilo Krummrich <dakr@...hat.com> writes:

[...]

> +
> +macro_rules! define_write {
> +    ($(#[$attr:meta])* $name:ident, $try_name:ident, $type_name:ty) => {
> +        /// Write IO data from a given offset known at compile time.
> +        ///
> +        /// Bound checks are performed on compile time, hence if the offset is not known at compile
> +        /// time, the build will fail.
> +        $(#[$attr])*
> +        #[inline]
> +        pub fn $name(&self, value: $type_name, offset: usize) {
> +            let addr = self.io_addr_assert::<$type_name>(offset);
> +
> +            unsafe { bindings::$name(value, addr as _, ) }
> +        }
> +
> +        /// Write IO data from a given offset.
> +        ///
> +        /// Bound checks are performed on runtime, it fails if the offset (plus the type size) is
> +        /// out of bounds.
> +        $(#[$attr])*
> +        pub fn $try_name(&self, value: $type_name, offset: usize) -> Result {
> +            let addr = self.io_addr::<$type_name>(offset)?;
> +
> +            unsafe { bindings::$name(value, addr as _) }
> +            Ok(())
> +        }
> +    };
> +}
> +

I am curious why we do not need `&mut self` to write to this memory? Is
it OK to race on these writes?


Best regards,
Andreas