linux-kernel - Re: [PATCH v8 4/7] rust: time: Add wrapper for fsleep function

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAH5fLggUGT83saC++M-kd57bGvWj5dwAgbWZ95r+PHz_B67NLQ@mail.gmail.com>
Date: Fri, 17 Jan 2025 10:13:08 +0100
From: Alice Ryhl <aliceryhl@...gle.com>
To: FUJITA Tomonori <fujita.tomonori@...il.com>
Cc: linux-kernel@...r.kernel.org, rust-for-linux@...r.kernel.org, 
	netdev@...r.kernel.org, andrew@...n.ch, hkallweit1@...il.com, 
	tmgross@...ch.edu, ojeda@...nel.org, alex.gaynor@...il.com, gary@...yguo.net, 
	bjorn3_gh@...tonmail.com, benno.lossin@...ton.me, a.hindborg@...sung.com, 
	anna-maria@...utronix.de, frederic@...nel.org, tglx@...utronix.de, 
	arnd@...db.de, jstultz@...gle.com, sboyd@...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
Subject: Re: [PATCH v8 4/7] rust: time: Add wrapper for fsleep function

On Fri, Jan 17, 2025 at 10:01 AM FUJITA Tomonori
<fujita.tomonori@...il.com> wrote:
>
> On Fri, 17 Jan 2025 16:53:26 +0900 (JST)
> FUJITA Tomonori <fujita.tomonori@...il.com> wrote:
>
> > On Thu, 16 Jan 2025 10:27:02 +0100
> > Alice Ryhl <aliceryhl@...gle.com> wrote:
> >
> >>> +/// This function can only be used in a nonatomic context.
> >>> +pub fn fsleep(delta: Delta) {
> >>> +    // The argument of fsleep is an unsigned long, 32-bit on 32-bit architectures.
> >>> +    // Considering that fsleep rounds up the duration to the nearest millisecond,
> >>> +    // set the maximum value to u32::MAX / 2 microseconds.
> >>> +    const MAX_DURATION: Delta = Delta::from_micros(u32::MAX as i64 >> 1);
> >>
> >> Hmm, is this value correct on 64-bit platforms?
> >
> > You meant that the maximum can be longer on 64-bit platforms? 2147484
> > milliseconds is long enough for fsleep's duration?
> >
> > If you prefer, I use different maximum durations for 64-bit and 32-bit
> > platforms, respectively.
>
> How about the following?
>
> const MAX_DURATION: Delta = Delta::from_micros(usize::MAX as i64 >> 1);

Why is there a maximum in the first place? Are you worried about
overflow on the C side?

Alice