linux-kernel - Re: [PATCH v3 2/2] rust: task: Add Rust version of might

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Message-ID: <aFF1AdgffZB8j0M1@Mac.home>
Date: Tue, 17 Jun 2025 07:00:33 -0700
From: Boqun Feng <boqun.feng@...il.com>
To: FUJITA Tomonori <fujita.tomonori@...il.com>
Cc: miguel.ojeda.sandonis@...il.com, linux-kernel@...r.kernel.org,
	rust-for-linux@...r.kernel.org, ojeda@...nel.org,
	alex.gaynor@...il.com, gary@...yguo.net, bjorn3_gh@...tonmail.com,
	benno.lossin@...ton.me, a.hindborg@...sung.com,
	aliceryhl@...gle.com, tmgross@...ch.edu, dakr@...nel.org,
	mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
	vincent.guittot@...aro.org, dietmar.eggemann@....com,
	rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
	vschneid@...hat.com, pmladek@...e.com, mingo@...nel.org
Subject: Re: [PATCH v3 2/2] rust: task: Add Rust version of might_sleep()

On Tue, Jun 17, 2025 at 09:42:07PM +0900, FUJITA Tomonori wrote:
> On Tue, 17 Jun 2025 10:02:22 +0200
> Miguel Ojeda <miguel.ojeda.sandonis@...il.com> wrote:
> 
> > On Tue, Jun 17, 2025 at 5:05 AM FUJITA Tomonori
> > <fujita.tomonori@...il.com> wrote:
> >>
> >> How about adding a link to the header file where the might_sleep macro
> >> is defined, like this?
> > 
> > Sounds good to me. Though, for APIs that have rendered docs, we
> > typically point to those instead:
> > 
> >     https://docs.kernel.org/driver-api/basics.html#c.might_sleep
> 
> Ah, somehow, I overlooked that. Thanks!
> 
> Boqun, here is the revised version.
> 

Thanks, applied. Although I kept the parentheses because might_sleep()
is a C macro, in the same spirit of [1].

[1]: https://docs.kernel.org/process/maintainer-tip.html#function-references-in-changelogs

Regards,
Boqun

> diff --git a/rust/helpers/task.c b/rust/helpers/task.c
> index 31c33ea2dce6..2c85bbc2727e 100644
> --- a/rust/helpers/task.c
> +++ b/rust/helpers/task.c
> @@ -1,7 +1,13 @@
>  // SPDX-License-Identifier: GPL-2.0
>  
> +#include <linux/kernel.h>
>  #include <linux/sched/task.h>
>  
> +void rust_helper_might_resched(void)
> +{
> +	might_resched();
> +}
> +
>  struct task_struct *rust_helper_get_current(void)
>  {
>  	return current;
> diff --git a/rust/kernel/task.rs b/rust/kernel/task.rs
> index 834368313088..b79d19deb02e 100644
> --- a/rust/kernel/task.rs
> +++ b/rust/kernel/task.rs
> @@ -400,3 +400,27 @@ fn eq(&self, other: &Kuid) -> bool {
>  }
>  
>  impl Eq for Kuid {}
> +
> +/// Annotation for functions that can sleep.
> +///
> +/// Equivalent to the C side [`might_sleep`] macro, this function serves as
> +/// a debugging aid and a potential scheduling point.
> +///
> +/// This function can only be used in a nonatomic context.
> +///
> +/// [`might_sleep`]: https://docs.kernel.org/driver-api/basics.html#c.might_sleep
> +#[track_caller]
> +#[inline]
> +pub fn might_sleep() {
> +    #[cfg(CONFIG_DEBUG_ATOMIC_SLEEP)]
> +    {
> +        let loc = core::panic::Location::caller();
> +        let file = kernel::file_from_location(loc);
> +
> +        // SAFETY: `file.as_ptr()` is valid for reading and guaranteed to be nul-terminated.
> +        unsafe { crate::bindings::__might_sleep(file.as_ptr().cast(), loc.line() as i32) }
> +    }
> +
> +    // SAFETY: Always safe to call.
> +    unsafe { crate::bindings::might_resched() }
> +}