linux-kernel - Re: [PATCH v10 01/13] rust: hrtimer: introduce hrtimer support

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Message-ID: <D8A2W9JIGFX3.20YC7NQRET0XG@proton.me>
Date: Fri, 07 Mar 2025 13:46:32 +0000
From: Benno Lossin <benno.lossin@...ton.me>
To: Andreas Hindborg <a.hindborg@...nel.org>
Cc: Miguel Ojeda <ojeda@...nel.org>, Anna-Maria Behnsen <anna-maria@...utronix.de>, Frederic Weisbecker <frederic@...nel.org>, Thomas Gleixner <tglx@...utronix.de>, Danilo Krummrich <dakr@...nel.org>, Alex Gaynor <alex.gaynor@...il.com>, Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>, Björn Roy Baron <bjorn3_gh@...tonmail.com>, Alice Ryhl <aliceryhl@...gle.com>, Trevor Gross <tmgross@...ch.edu>, Lyude Paul <lyude@...hat.com>, Guangbo Cui <2407018371@...com>, Dirk Behme <dirk.behme@...il.com>, Daniel Almeida <daniel.almeida@...labora.com>, Tamir Duberstein <tamird@...il.com>, Markus Elfring <Markus.Elfring@....de>, rust-for-linux@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v10 01/13] rust: hrtimer: introduce hrtimer support

On Fri Mar 7, 2025 at 2:10 PM CET, Andreas Hindborg wrote:
> "Benno Lossin" <benno.lossin@...ton.me> writes:
>> On Fri Mar 7, 2025 at 11:11 AM CET, Andreas Hindborg wrote:
>>> +/// Use to implement the [`HasHrTimer<T>`] trait.
>>> +///
>>> +/// See [`module`] documentation for an example.
>>> +///
>>> +/// [`module`]: crate::time::hrtimer
>>> +#[macro_export]
>>> +macro_rules! impl_has_hr_timer {
>>> +    (
>>> +        impl$({$($generics:tt)*})?
>>> +            HasHrTimer<$timer_type:ty>
>>> +            for $self:ty
>>> +        { self.$field:ident }
>>> +        $($rest:tt)*
>>> +    ) => {
>>> +        // SAFETY: This implementation of `raw_get_timer` only compiles if the
>>> +        // field has the right type.
>>> +        unsafe impl$(<$($generics)*>)? $crate::time::hrtimer::HasHrTimer<$timer_type> for $self {
>>> +
>>> +            #[inline]
>>> +            unsafe fn raw_get_timer(this: *const Self) ->
>>> +                *const $crate::time::hrtimer::HrTimer<$timer_type>
>>> +            {
>>> +                // SAFETY: The caller promises that the pointer is not dangling.
>>> +                unsafe {
>>> +                    ::core::ptr::addr_of!((*this).$field)
>>> +                }
>>> +            }
>>> +
>>> +            #[inline]
>>> +            unsafe fn timer_container_of(ptr: *mut $crate::time::hrtimer::HrTimer<$timer_type>) ->
>>> +                *mut Self
>>
>> This formatting looks a bit weird, (macro formatting is annoying, I
>> know).
>
> How would you change it?

Just use `rustfmt` (copy the macro arm, replace all `$` with `_` in
names and remove repetitions, `rustfmt` and then revert. You're lucky,
since you only have one repetition that doesn't cause the line to go
over the 100 column threshold):

        // SAFETY: This implementation of `raw_get_timer` only compiles if the
        // field has the right type.
        unsafe impl$(<$($generics)*>)? $crate::time::hrtimer::HasHrTimer<$timer_type> for $self {

            #[inline]
            unsafe fn raw_get_timer(
                this: *const Self,
            ) -> *const $crate::time::hrtimer::HrTimer<$timer_type> {
                // SAFETY: The caller promises that the pointer is not dangling.
                unsafe { ::core::ptr::addr_of!((*this).$field) }
            }

            #[inline]
            unsafe fn timer_container_of(
                ptr: *mut $crate::time::hrtimer::HrTimer<$timer_type>,
            ) -> *mut Self {
                // SAFETY: As per the safety requirement of this function, `ptr`
                // is pointing inside a `$timer_type`.
                unsafe { ::kernel::container_of!(ptr, $timer_type, $field).cast_mut() }
            }
        }

---
Cheers,
Benno